If you like this book, please consider + spreading the word or + + buying me a coffee + +
+ ``` +include-after: +- | + ```{=html} +
+
+
+ ```
+---
+```
+
+下面几个变量需要注意一下：
+
+- `header-includes` 变量包含将要嵌入 `` 标签的 HTML 文本。
+- 调用变量后的下一行必须是 `- |`。再往下一行必须以与 `|` 对齐的三个反引号开始，否则 Pandoc 将无法识别。`{= html}` 告诉 Pandoc 其中的内容是原始文本，不应该作为 Markdown 处理。（为此，需要检查 Pandoc 中的 `raw_attribute` 扩展是否已启用。要进行此检查，键入 `pandoc --list-extensions | grep raw` 并确保返回的列表包含名为 `+ raw_html` 的项目，加号表示已启用。）
+- 变量 `include-before` 在网页开头添加一些 HTML 文本，此处我请求读者帮忙宣传我的书或给我打赏。
+- `include-after` 变量在网页末尾添加原始 HTML 文本，同时显示我的图书许可证。
+
+这些只是其中一部分可用的变量，查看 HTML 中的模板变量（我的文章 [Pandoc简介][1] 中介绍了如何查看 LaTeX 的模版变量，查看 HTML 模版变量的过程是相同的）对其余变量进行了解。
+
+#### 将网页分成多章
+
+网页可以作为一个整体生成，这会产生一个包含所有内容的长页面；也可以分成多章，我认为这样会更容易阅读。我将解释如何将网页划分为多章，以便读者不会被长网页吓到。
+
+为了使网页易于在 GitHub Pages 上部署，需要创建一个名为 `docs` 的根文件夹（这是 GitHub Pages 默认用于渲染网页的根文件夹）。然后我们需要为 `docs` 下的每一章创建文件夹，将 HTML 内容放在各自的文件夹中，将文件内容放在名为 `index.html` 的文件中。
+
+例如，`about.md` 文件将转换成名为 `index.html` 的文件，该文件位于名为 `about`（`about/index.html`）的文件夹中。这样，当用户键入 `http://+
+
+
+ ` 和 `
` 来包裹文本，那么浏览器将识别 `` 和 `
` 中的文本是一个段落。我们这样做： + +``` +After all the battles we fought together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+``` + +通过在 `` 和 `
`中编写段落，你创建了一个 HTML 元素。一个网页就是 HTML 元素的集合。 + +让我们首先来认识一些术语：`` 是开始标签，`
` 是结束标签，“p” 是标签名称。元素开始和结束标签之间的文本是元素的内容。 + +### “style” 属性 + +在上面，你将看到文本覆盖屏幕的整个宽度。 + +我们不希望这样。没有人想要阅读这么长的行。让我们设定段落宽度为 550px。 + +我们可以通过使用元素的 `style` 属性来实现。你可以在其 `style` 属性中定义元素的样式（例如，在我们的示例中为宽度）。以下行将在 `p` 元素上创建一个空样式属性： + +``` +...
+``` + +你看到那个空的 `""` 了吗？这就是我们定义元素外观的地方。现在我们要将宽度设置为 550px。我们这样做： + +``` ++ After all the battles we fought together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+``` + +我们将 `width` 属性设置为 `550px`，用冒号 `:` 分隔，以分号 `;` 结束。 + +另外，注意我们如何将 `` 和 `
` 放在单独的行中，文本内容用一个制表符缩进。像这样设置代码使其更具可读性。 + +### HTML 中的列表 + +接下来，蝙蝠侠希望列出他所钦佩的人的一些优点，例如： + +``` +You complete my darkness with your light. I love: +- the way you see good in the worst things +- the way you handle emotionally difficult situations +- the way you look at Justice +I have learned a lot from you. You have occupied a special place in my heart over time. +``` + +这看起来很简单。 + +让我们继续，在 `` 下面复制所需的文本： + +``` ++ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
++ You complete my darkness with your light. I love: + - the way you see good in the worse + - the way you handle emotionally difficult situations + - the way you look at Justice + I have learned a lot from you. You have occupied a special place in my heart over the time. +
+``` + +保存并刷新浏览器。 + + + +哇！这里发生了什么，我们的列表在哪里？ + +如果你仔细观察，你会发现没有显示换行符。在代码中我们在新的一行中编写列表项，但这些项在浏览器中显示在一行中。 + +如果你想在 HTML（新行）中插入换行符，你必须使用 ``。让我们来使用 `
`，看看它长什么样： + +``` +
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+
+ You complete my darkness with your light. I love:
+ - the way you see good in the worse
+ - the way you handle emotionally difficult situations
+ - the way you look at Justice
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
`，但第二个段落仍然是从一个新行开始，这是因为 `
` 元素会自动插入换行符。 + +我们使用纯文本编写列表，但是有两个标签可以供我们使用来达到相同的目的：`
- ` and `
- `。
+
+让我们解释一下名字的意思：ul 代表无序列表，li 代表列表项目。让我们使用它们来展示我们的列表：
+
+```
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+``` + +``` ++ You complete my darkness with your light. I love: +
-
+
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
`，因为每个 ` - ` 会自动显示在新行中 +* 我们将每个列表项包含在 `
- ` 和 ` ` 之间 +* 我们将所有列表项的集合包裹在 `
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
- the way you see good in the worse +
- the way you handle emotionally difficult situations +
- the way you look at Justice +
- `：显示列表
+ * ``：用于分组我们信件的元素 + * `
`、`
`：用于标题和子标题 + * `
`：用于插入图像 + * ``、``：用于粗体和斜体文字样式 + * `. - -* Linked stylesheet: We write styles of all the elements in a separate file with .css extension. This file is called Stylesheet. - -Let’s have a look at how we defined the inline style of the “div” until now: - -``` -
-``` - -We can write this same style inside `` like this: - -``` -div{ - width:550px; -} -``` - -In embedded styling, the styles we write are separate from the elements. So we need a way to relate the element and its style. The first word “div” does exactly that. It lets the browser know that whatever style is inside the curly braces `{…}` belongs to the “div” element. Since this phrase determines which element to apply the style to, it’s called a selector. - -The way we write style remains same: property(width) and value(550px) separated by a colon(:) and ended by a semicolon(;). - -Let’s remove inline style from our “div” and “img” element and write it inside the ` -``` - -``` ---``` - -Save and refresh, and the result should remain the same. - -There is one big problem though — what if there is more than one “div” and “img” element in our HTML file? The styles that we defined for div and img inside the “style” element will apply to every div and img on the page. - -If you add another div in your code in the future, then that div will also become 550px wide. We don’t want that. - -We want to apply our styles to the specific div and img that we are using right now. To do this, we need to give our div and img element unique ids. Here’s how you can give an id to an element using its “id” attribute: - -``` -Bat Letter
-
- - After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. -
-``` - -``` -You are the light of my life
-- You complete my darkness with your light. I love: -
--
-
- the way you see good in the worse -
- the way you handle emotionally difficult situations -
- the way you look at Justice -
- I have learned a lot from you. You have occupied a special place in my heart over the time. -
-I have a confession to make
-- It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart. -
-- I don't show my emotions, but I think this man behind the mask is falling for you. -
-I love you Superman.
-- Your not-so-secret-lover,
-
- Batman --``` - -and here’s how to use th diff --git a/sources/tech/20180217 Louis-Philippe Véronneau .md b/sources/tech/20180217 Louis-Philippe Véronneau .md deleted file mode 100644 index bab2f4c169..0000000000 --- a/sources/tech/20180217 Louis-Philippe Véronneau .md +++ /dev/null @@ -1,59 +0,0 @@ -Louis-Philippe Véronneau - -====== -I've been watching [Critical Role][1]1 for a while now and since I've started my master's degree I haven't had much time to sit down and watch the show on YouTube as I used to do. - -I thus started listening to the podcasts instead; that way, I can listen to the show while I'm doing other productive tasks. Pretty quickly, I grew tired of manually downloading every episode each time I finished the last one. To make things worst, the podcast is hosted on PodBean and they won't let you download episodes on a mobile device without their app. Grrr. - -After the 10th time opening the terminal on my phone to download the podcast using some `wget` magic I decided enough was enough: I was going to write a dumb script to download them all in one batch. - -I'm a little ashamed to say it took me more time than I had intended... The PodBean website uses semi-randomized URLs, so I could not figure out a way to guess the paths to the hosted audio files. I considered using `youtube-dl` to get the DASH version of the show on YouTube, but Google has been heavily throttling DASH streams recently. Not cool Google. - -I then had the idea to use iTune's RSS feed to get the audio files. Surely they would somehow be included there? Of course Apple doesn't give you a simple RSS feed link on the iTunes podcast page, so I had to rummage around and eventually found out this is the link you have to use: -``` -https://itunes.apple.com/lookup?id=1243705452&entity=podcast - -``` - -Surprise surprise, from the json file this links points to, I found out the main Critical Role podcast page [has a proper RSS feed][2]. To my defense, the RSS button on the main podcast page brings you to some PodBean crap page. - -Anyway, once you have the RSS feed, it's only a matter of using `grep` and `sed` until you get what you want. - -Around 20 minutes later, I had downloaded all the episodes, for a total of 22Gb! Victory dance! - -Video clip loop of the Critical Role doing a victory dance. - -### Script - -Here's the bash script I wrote. You will need `recode` to run it, as the RSS feed includes some HTML entities. -``` -# Get the whole RSS feed -wget -qO /tmp/criticalrole.rss http://criticalrolepodcast.geekandsundry.com/feed/ - -# Extract the URLS and the episode titles -mp3s=( $(grep -o "http.\+mp3" /tmp/criticalrole.rss) ) -titles=( $(tail -n +45 /tmp/criticalrole.rss | grep -o ".\+ " \ - | sed -r 's@@@g; s@ @\\@g' | recode html..utf8) ) - -# Download all the episodes under their titles -for i in ${!titles[*]} -do - wget -qO "$(sed -e "s@\\\@\\ @g" <<< "${titles[$i]}").mp3" ${mp3s[$i]} -done - -``` - -1 - For those of you not familiar with Critical Role, it's web series where a group of voice actresses and actors from LA play Dungeons & Dragons. It's so good even people like me who never played D&D can enjoy it.. - --------------------------------------------------------------------------------- - -via: https://veronneau.org/downloading-all-the-critical-role-podcasts-in-one-batch.html - -作者：[Louis-Philippe Véronneau][a] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://veronneau.org/ -[1]:https://en.wikipedia.org/wiki/Critical_Role -[2]:http://criticalrolepodcast.geekandsundry.com/feed/ diff --git a/sources/tech/20180220 JSON vs XML vs TOML vs CSON vs YAML.md b/sources/tech/20180220 JSON vs XML vs TOML vs CSON vs YAML.md new file mode 100644 index 0000000000..eeb290c82b --- /dev/null +++ b/sources/tech/20180220 JSON vs XML vs TOML vs CSON vs YAML.md @@ -0,0 +1,212 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (JSON vs XML vs TOML vs CSON vs YAML) +[#]: via: (https://www.zionandzion.com/json-vs-xml-vs-toml-vs-cson-vs-yaml/) +[#]: author: (Tim Anderson https://www.zionandzion.com) + +JSON vs XML vs TOML vs CSON vs YAML +====== + + +### A Super Serious Segment About Sets, Subsets, and Supersets of Sample Serialization + +I’m a developer. I read code. I write code. I write code that writes code. I write code that writes code for other code to read. It’s all very mumbo-jumbo, but beautiful in its own way. However, that last bit, writing code that writes code for other code to read, can get more convoluted than this paragraph—quickly. There are a lot of ways to do it. One not-so-convoluted way and a favorite among the developer community is through data serialization. For those who aren’t savvy on the super buzzword I just threw at you, data serialization is the process of taking some information from one system, churning it into a format that other systems can read, and then passing it along to those other systems. + +While there are enough [data serialization formats][1] out there to bury the Burj Khalifa, they all mostly fall into two categories: + + * simplicity for humans to read and write, + * and simplicity for machines to read and write. + + + +It’s difficult to have both as we humans enjoy loosely typed, flexible formatting standards that allow us to be more expressive, whereas machines tend to enjoy being told exactly what everything is without doubt or lack of detail, and consider “strict specifications” to be their favorite flavor of Ben & Jerry’s. + +Since I’m a web developer and we’re an agency who creates websites, we’ll stick to those special formats that web systems can understand, or be made to understand without much effort, and that are particularly useful for human readability: XML, JSON, TOML, CSON, and YAML. Each has benefits, cons, and appropriate use cases. + +### Facts First + +Back in the early days of the interwebs, [some really smart fellows][2] decided to put together a standard language which every system could read and creatively named it Standard Generalized Markup Language, or SGML for short. SGML was incredibly flexible and well defined by its publishers. It became the father of languages such as XML, SVG, and HTML. All three fall under the SGML specification, but are subsets with stricter rules and shorter flexibility. + +Eventually, people started seeing a great deal of benefit in having very small, concise, easy to read, and easy to generate data that could be shared programmatically between systems with very little overhead. Around that time, JSON was born and was able to fulfil all requirements. In turn, other languages began popping up to deal with more specialized cases such as CSON, TOML, and YAML. + +### XML: Ixnayed + +Originally, the XML language was amazingly flexible and easy to write, but its drawback was that it was verbose, difficult for humans to read, really difficult for computers to read, and had a lot of syntax that wasn’t entirely necessary to communicate information. + +Today, it’s all but dead for data serialization purposes on the web. Unless you’re writing HTML or SVG, both siblings to XML, you probably aren’t going to see XML in too many other places. Some outdated systems still use it today, but using it to pass data around tends to be overkill for the web. + +I can already hear the XML greybeards beginning to scribble upon their stone tablets as to why XML is ah-may-zing, so I’ll provide a small addendum: XML can be easy to read and write by systems and people. However, it is really, and I mean ridiculously, hard to create a system that can read it to specification. Here’s a simple, beautiful example of XML: + +``` ++ +``` + +Wonderful. Easy to read, reason about, write, and code a system that can read and write. But consider this example: + +``` +b"> ]> +Gambardella, Matthew +XML Developer's Guide +Computer +44.95 +2000-10-01 +An in-depth look at creating applications +with XML. ++ +b b +``` + +The above is 100% valid XML. Impossible to read, understand, or reason about. Writing code that can consume and understand this would cost at least 36 heads of hair and 248 pounds of coffee grounds. We don’t have that kind of time nor coffee, and most of us greybeards are balding nowadays. So let’s let it live only in our memory alongside [css hacks][3], [internet explorer 6][4], and [vacuum tubes][5]. + +### JSON: Juxtaposition Jamboree + +Okay, we’re all in agreement. XML = bad. So, what’s a good alternative? JavaScript Object Notation, or JSON for short. JSON (read like the name Jason) was invented by Brendan Eich, and made popular by the great and powerful Douglas Crockford, the [Dutch Uncle of JavaScript][6]. It’s used just about everywhere nowadays. The format is easy to write by both human and machine, fairly easy to [parse][7] with strict rules in the specification, and flexible—allowing deep nesting of data, all of the primitive data types, and interpretation of collections as either arrays or objects. JSON became the de facto standard for transferring data from one system to another. Nearly every language out there has built-in functionality for reading and writing it. + +JSON syntax is straightforward. Square brackets denote arrays, curly braces denote records, and two values separated by semicolons denote properties (or ‘keys’) on the left, and values on the right. All keys must be wrapped in double quotes: + +``` +{ +"books": [ +{ +"id": "bk102", +"author": "Crockford, Douglas", +"title": "JavaScript: The Good Parts", +"genre": "Computer", +"price": 29.99, +"publish_date": "2008-05-01", +"description": "Unearthing the Excellence in JavaScript" +} +] +} +``` + +This should make complete sense to you. It’s nice and concise, and has stripped much of the extra nonsense from XML to convey the same amount of information. JSON is king right now, and the rest of this article will go into other language formats that are nothing more than JSON boiled down in an attempt to be either more concise or more readable by humans, but follow very similar structure. + +### TOML: Truncated to Total Altruism + +TOML (Tom’s Obvious, Minimal Language) allows for defining deeply-nested data structures rather quickly and succinctly. The name-in-the-name refers to the inventor, [Tom Preston-Werner][8], an inventor and software developer who’s active in our industry. The syntax is a bit awkward when compared to JSON, and is more akin to an [ini file][9]. It’s not a bad syntax, but could take some getting used to: + +``` +[[books]] +id = 'bk101' +author = 'Crockford, Douglas' +title = 'JavaScript: The Good Parts' +genre = 'Computer' +price = 29.99 +publish_date = 2008-05-01T00:00:00+00:00 +description = 'Unearthing the Excellence in JavaScript' +``` + +A couple great features have been integrated into TOML, such as multiline strings, auto-escaping of reserved characters, datatypes such as dates, time, integers, floats, scientific notation, and “table expansion”. That last bit is special, and is what makes TOML so concise: + +``` +[a.b.c] +d = 'Hello' +e = 'World' +``` + +The above expands to the following: + +``` +{ +"a": { +"b": { +"c": { +"d": "Hello" +"e": "World" +} +} +} +} +``` + +You can definitely see how much you can save in both time and file length using TOML. There are few systems which use it or something very similar for configuration, and that is its biggest con. There simply aren’t very many languages or libraries out there written to interpret TOML. + +### CSON: Simple Samples Enslaved by Specific Systems + +First off, there are two CSON specifications. One stands for CoffeeScript Object Notation, the other stands for Cursive Script Object Notation. The latter isn’t used too often, so we won’t be getting into it. Let’s just focus on the CoffeeScript one. + +[CSON][10] will take a bit of intro. First, let’s talk about CoffeeScript. [CoffeeScript][11] is a language that runs through a compiler to generate JavaScript. It allows you to write JavaScript in a more syntactically concise way, and have it [transcompiled][12] into actual JavaScript, which you would then use in your web application. CoffeeScript makes writing JavaScript easier by removing a lot of the extra syntax necessary in JavaScript. A big one that CoffeeScript gets rid of is curly braces—no need for them. In that same token, CSON is JSON without the curly braces. It instead relies on indentation to determine hierarchy of your data. CSON is very easy to read and write and usually requires fewer lines of code than JSON because there are no brackets. + +CSON also offers up some extra niceties that JSON doesn’t have to offer. Multiline strings are incredibly easy to write, you can enter [comments][13] by starting a line with a hash, and there’s no need for separating key-value pairs with commas. + +``` +books: [ +id: 'bk102' +author: 'Crockford, Douglas' +title: 'JavaScript: The Good Parts' +genre: 'Computer' +price: 29.99 +publish_date: '2008-05-01' +description: 'Unearthing the Excellence in JavaScript' +] +``` + +Here’s the big issue with CSON. It’s **CoffeeScript** Object Notation. Meaning CoffeeScript is what you use to parse/tokenize/lex/transcompile or otherwise use CSON. CoffeeScript is the system that reads the data. If the intent of data serialization is to allow data to be passed from one system to another, and here we have a data serialization format that’s only read by a single system, well that makes it about as useful as a fireproof match, or a waterproof sponge, or that annoyingly flimsy fork part of a spork. + +If this format is adopted by other systems, it could be pretty useful in the developer world. Thus far that hasn’t happened in a comprehensive manner, so using it in alternative languages such as PHP or JAVA are a no-go. + +### YAML: Yielding Yips from Youngsters + +Developers rejoice, as YAML comes into the scene from [one of the contributors to Python][14]. YAML has the same feature set and similar syntax as CSON, a boatload of new features, and parsers available in just about every web programming language there is. It also has some extra features, like circular referencing, soft-wraps, multi-line keys, typecasting tags, binary data, object merging, and [set maps][15]. It has incredibly good human readability and writability, and is a superset of JSON, so you can use fully qualified JSON syntax inside YAML and all will work well. You almost never need quotes, and it can interpret most of your base data types (strings, integers, floats, booleans, etc.). + +``` +books: +- id: bk102 +author: Crockford, Douglas +title: 'JavaScript: The Good Parts' +genre: Computer +price: 29.99 +publish_date: !!str 2008-05-01 +description: Unearthing the Excellence in JavaScript +``` + +The younglings of the industry are rapidly adopting YAML as their preferred data serialization and system configuration format. They are smart to do so. YAML has all the benefits of being as terse as CSON, and all the features of datatype interpretation as JSON. YAML is as easy to read as Canadians are to hang out with. + +There are two issues with YAML that stick out to me, and the first is a big one. At the time of this writing, YAML parsers haven’t yet been built into very many languages, so you’ll need to use a third-party library or extension for your chosen language to parse .yaml files. This wouldn’t be a big deal, however it seems most developers who’ve created parsers for YAML have chosen to throw “additional features” into their parsers at random. Some allow [tokenization][16], some allow [chain referencing][17], some even allow inline calculations. This is all well and good (sort of), except that none of these features are part of the specification, and so are difficult to find amongst other parsers in other languages. This results in system-locking; you end up with the same issue that CSON is subject to. If you use a feature found in only one parser, other parsers won’t be able to interpret the input. Most of these features are nonsense that don’t belong in a dataset, but rather in your application logic, so it’s best to simply ignore them and write your YAML to specification. + +The second issue is there are few parsers that yet completely implement the specification. All the basics are there, but it can be difficult to find some of the more complex and newer things like soft-wraps, document markers, and circular references in your preferred language. I have yet to see an absolute need for these things, so hopefully they shouldn’t slow you down too much. With the above considered, I tend to keep to the more matured feature set presented in the [1.1 specification][18], and avoid the newer stuff found in the [1.2 specification][19]. However, programming is an ever-evolving monster, so by the time you finish reading this article, you’re likely to be able to use the 1.2 spec. + +### Final Philosophy + +The final word here is that each serialization language should be treated with a case-by-case reverence. Some are the bee’s knees when it comes to machine readability, some are the cat’s meow for human readability, and some are simply gilded turds. Here’s the ultimate breakdown: If you are writing code for other code to read, use YAML. If you are writing code that writes code for other code to read, use JSON. Finally, if you are writing code that transcompiles code into code that other code will read, rethink your life choices. + +-------------------------------------------------------------------------------- + +via: https://www.zionandzion.com/json-vs-xml-vs-toml-vs-cson-vs-yaml/ + +作者：[Tim Anderson][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.zionandzion.com +[b]: https://github.com/lujun9972 +[1]: https://en.wikipedia.org/wiki/Comparison_of_data_serialization_formats +[2]: https://en.wikipedia.org/wiki/Standard_Generalized_Markup_Language#History +[3]: https://www.quirksmode.org/css/csshacks.html +[4]: http://www.ie6death.com/ +[5]: https://en.wikipedia.org/wiki/Vacuum_tube +[6]: https://twitter.com/BrendanEich/status/773403975865470976 +[7]: https://en.wikipedia.org/wiki/Parsing#Parser +[8]: https://en.wikipedia.org/wiki/Tom_Preston-Werner +[9]: https://en.wikipedia.org/wiki/INI_file +[10]: https://github.com/bevry/cson#what-is-cson +[11]: http://coffeescript.org/ +[12]: https://en.wikipedia.org/wiki/Source-to-source_compiler +[13]: https://en.wikipedia.org/wiki/Comment_(computer_programming) +[14]: http://clarkevans.com/ +[15]: http://exploringjs.com/es6/ch_maps-sets.html +[16]: https://www.tutorialspoint.com/compiler_design/compiler_design_lexical_analysis.htm +[17]: https://en.wikipedia.org/wiki/Fluent_interface +[18]: http://yaml.org/spec/1.1/current.html +[19]: http://www.yaml.org/spec/1.2/spec.html diff --git a/sources/tech/20180226 -Getting to Done- on the Linux command line.md b/sources/tech/20180226 -Getting to Done- on the Linux command line.md deleted file mode 100644 index c325a0d884..0000000000 --- a/sources/tech/20180226 -Getting to Done- on the Linux command line.md +++ /dev/null @@ -1,126 +0,0 @@ -'Getting to Done' on the Linux command line -====== - - -There is a lot of talk about getting things done at the command line. How many articles are there about using obscure flags with `ls`, nifty regular expressions with Sed and Awk, and how to parse out lots of text with Perl? That isn't what this is about. - -This is about [Getting _to_ Done][1], making sure that the stuff we have to do actually gets tracked and done using tools that don't require a graphical desktop, a web browser, or an internet connection. To do this, we'll look at four ways of tracking your to-do list: plaintext files, Todo.txt, TaskWarrior, and Org-mode. - -### Plain (and simple) text - - -![plaintext][3] - -I like to use Vim, but you can use Nano too. - -The most straightforward way to manage your to-do list is using a plaintext file in your editor of choice. Just open an empty file and add tasks, one per line. When you are done, delete the line. Simple, effective, and it doesn't matter what you use to do it. There are a couple of drawbacks to this method, though. Once you delete a line and save the file, it is gone forever. That can be a problem if you have to report on what you have done this week or last week. And while using a simple file is flexible, it can also get cluttered really easily. - -### Todo.txt: Plaintext leveled up - - -![todo.txt screen][5] - -Neat, organized, and easy to use - -That leads us to the [Todo.txt][6] file format and application. Installation is simple—[download][7] the latest release from GitHub and run `sudo make install` from the unpacked archive. - - -![Installing todo.txt][9] - -It works from a Git clone as well. - -Todo.txt makes it very easy to add tasks, list tasks, and mark them as done: - -| `todo.sh add "Some Task"` | add "Some Task" to my todo list | -| `todo.sh ls` | list all my tasks | -| `todo.sh ls due:2018-02-15` | list all tasks due on February 15, 2018 | -| `todo.sh do 3` | mark task number 3 as "done" | - -The actual list is still in plaintext, and you can edit it with your favorite text editor as long as you follow the [correct format][10]. - -There is also a very robust help built into the application. - - -![Syntax highlighting in todo.txt][12] - -You can even get syntax highlighting. - -There is also a large selection of add-ons, as well as specifications for writing your own. There are even browser extensions, mobile apps, and desktop apps that support the Todo.txt format. - - -![GNOME extensions in todo.txt][14] - -Even GNOME extensions. - -The biggest drawback to Todo.txt is the lack of an automatic or built-in synchronization mechanism. Most (if not all) of the browser extensions and mobile apps require Dropbox to perform synchronization between the app and the copy on your desktop. If you would like something with sync built-in, we have... - -### Taskwarrior: Now we're cooking with Python - -[Taskwarrior][15] is a Python application with many of the same features as Todo.txt. However, it stores the data in a database and has built-in synchronization capabilities. It also keeps track of what is next, notes how old tasks are, and will warn you if you have something more important to do than what you just did. - -[Installation][16] of Taskwarrior can be done either with your distribution's package manager, through Python's `pip` utility, or built from source. Using it is also pretty straightforward, with commands similar to Todo.txt: - -| `task add "Some Task"` | Add "Some Task" to the list | -| `task list` | List all tasks | -| `task list due ``:today` | List all tasks due on today's date | -| `task do 3` | Complete task number 3 | - -Taskwarrior also has some pretty nice text user interfaces. - -![Taskwarrior in Vit][18] - -I like Vit, which was inspired by Vim. - -Unlike Todo.txt, Taskwarrior can synchronize with a local or remote server. A very basic synchronization server called `taskd` is available if you wish to run your own, and there are several services available if you do not. - -Taskwarrior also has a thriving and extensive ecosystem of add-ons and extensions, as well as mobile and desktop apps. - -![Taskwarrior on GNOME][20] - -Taskwarrior looks really nice on GNOME. - -The only disadvantage to Taskwarrior is that, unlike the other programs listed here, you cannot directly modify the to-do list itself. You can export the task list to various formats, modify the export, and then re-import the files, but it is a lot clunkier than just opening the file directly in a text editor. - -Which brings us to the most powerful of them all... - -### Emacs Org-mode: Hulk smash tasks - -![Org-mode][22] - -Emacs has everything. - -Emacs [Org-mode][23] is by far the most powerful, most flexible open source to-do list manager out there. It supports multiple files, uses plaintext, is almost infinitely customizable, and understands calendars, due dates, and schedules. It is also significantly more complicated to set up than the other applications listed here. But once it is set up, it does everything the other applications do and more. If you are familiar with or a fan of [Bullet Journals][24], Org-mode is possibly the closest you can get on a computer. - -Org-mode will run anywhere Emacs runs, and there are a few mobile applications that can interact with it as well. Unfortunately, there are no desktop apps or browser extensions that support Org. Despite all that, Org-mode is still one of the best applications for tracking your to-do list, since it is so very powerful. - -### Choose your tool - -In the end, the goal of all these programs is to help you track what you need to do and make sure you don't forget to do something. While they all have the same basic functions, choosing which one is right for you depends on a lot of factors. Do you want synchronization built-in or not? Do you need a mobile app? Do any of the add-ons include a "must have" feature? Whatever your choice, remember that the program alone cannot make you more organized, but it can help. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/2/getting-to-done-agile-linux-command-line - -作者：[Kevin Sonney][a] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: -[1]:https://www.scruminc.com/getting-done/ -[3]:https://opensource.com/sites/default/files/u128651/plain-text.png (plaintext) -[5]:https://opensource.com/sites/default/files/u128651/todo-txt.png (todo.txt screen) -[6]:http://todotxt.org/ -[7]:https://github.com/todotxt/todo.txt-cli/releases -[9]:https://opensource.com/sites/default/files/u128651/todo-txt-install.png (Installing todo.txt) -[10]:https://github.com/todotxt/todo.txt -[12]:https://opensource.com/sites/default/files/u128651/todo-txt-vim.png (Syntax highlighting in todo.txt) -[14]:https://opensource.com/sites/default/files/u128651/tod-txt-gnome.png (GNOME extensions in todo.txt) -[15]:https://taskwarrior.org/ -[16]:https://taskwarrior.org/download/ -[18]:https://opensource.com/sites/default/files/u128651/taskwarrior-vit.png (Taskwarrior in Vit) -[20]:https://opensource.com/sites/default/files/u128651/taskwarrior-gnome.png (Taskwarrior on GNOME) -[22]:https://opensource.com/sites/default/files/u128651/emacs-org-mode.png (Org-mode) -[23]:https://orgmode.org/ -[24]:http://bulletjournal.com/ diff --git a/sources/tech/20180302 How to manage your workstation configuration with Ansible.md b/sources/tech/20180302 How to manage your workstation configuration with Ansible.md deleted file mode 100644 index fd24cd48ed..0000000000 --- a/sources/tech/20180302 How to manage your workstation configuration with Ansible.md +++ /dev/null @@ -1,170 +0,0 @@ -How to manage your workstation configuration with Ansible -====== - - - -Configuration management is a very important aspect of both server administration and DevOps. The "infrastructure as code" methodology makes it easy to deploy servers in various configurations and dynamically scale an organization's resources to keep up with user demands. But less attention is paid to individual administrators who want to automate the setup of their own laptops and desktops (workstations). - -In this series, I'll show you how to automate your workstation setup via [Ansible][1] , which will allow you to easily restore your entire configuration if you want or need to reload your machine. In addition, if you have multiple workstations, you can use this same approach to make the configuration identical on each. In this first article, we'll set up basic configuration management for our personal or work computers and set the foundation for the rest of the series. By the end of this article, you'll have a working setup to benefit from right away. Each article will automate more things and grow in complexity. - -### Why Ansible? - -Many configuration management solutions are available, including Salt Stack, Chef, and Puppet. I prefer Ansible because it's lighter in terms of resource utilization, its syntax is easier to read, and when harnessed properly it can revolutionize your configuration management. Ansible's lightweight nature is especially relevant to the topic at hand, because we may not want to run an entire server just to automate the setup of our laptops and desktops. Ideally, we want something fast; something we can use to get up and running quickly should we need to restore our workstations or synchronize our configuration between multiple machines. My specific method for Ansible (which I'll demonstrate in this article) is perfect for this—there's no server to maintain. You just download your configuration and run it. - -### My approach - -Typically, Ansible is run from a central server. It utilizes an inventory file, which is a text file that contains a list of all the hosts and their IP addresses or domain names we want Ansible to manage. This is great for static environments, but it is not ideal for workstations. The reason being we really don't know what the status of our workstations will be at any one moment. Perhaps I powered down my desktop or my laptop may be suspended and stowed in my bag. In either case, the Ansible server would complain, as it can't reach my machines if they are offline. We need something that's more of an on-demand approach, and the way we'll accomplish that is by utilizing `ansible-pull`. The `ansible-pull` command, which is part of Ansible, allows you to download your configuration from a Git repository and apply it immediately. You won't need to maintain a server or an inventory list; you simply run the `ansible-pull` command, feed it a Git repository URL, and it will do the rest for you. - -### Getting started - -First, install Ansible on the computer you want it to manage. One problem is that a lot of distributions ship with an older version. I can tell you from experience you'll definitely want the latest version available. New features are introduced into Ansible quite frequently, and if you're running an older version, example syntax you find online may not be functional because it's using features that aren't implemented in the version you have installed. Even point releases have quite a few new features. One example of this is the `dconf` module, which is new to Ansible as of 2.4. If you try to utilize syntax that makes use of this module, unless you have 2.4 or newer it will fail. In Ubuntu and its derivatives, we can easily install the latest version of Ansible with the official personal package archive ([PPA][2]). The following commands will do the trick: -``` -sudo apt-get install software-properties-common - -sudo apt-add-repository ppa:ansible/ansible - -sudo apt-get update - -sudo apt-get install ansible - -``` - -If you're not using Ubuntu, [consult Ansible's documentation][3] on how to obtain it for your platform. - -Next, we'll need a Git repository to hold our configuration. The easiest way to satisfy this requirement is to create an empty repository on GitHub, or you can utilize your own Git server if you have one. To keep things simple, I'll assume you're using GitHub, so adjust the commands if you're using something else. Create a repository in GitHub; you'll end up with a repository URL that will be similar to this: -``` -git@github.com:/ansible.git - -``` - -Clone that repository to your local working directory (ignore any message that complains that the repository is empty): -``` -git clone git@github.com: /ansible.git - -``` - -Now we have an empty repository we can work with. Change your working directory to be inside the repository (`cd ./ansible` for example) and create a file named `local.yml` in your favorite text editor. Place the following configuration in that file: -``` -- hosts: localhost - - become: true - - tasks: - - - name: Install htop - - apt: name=htop - -``` - -The file you just created is known as a **playbook** , and the instruction to install `htop` (a package I arbitrarily picked to serve as an example) is known as a **play**. The playbook itself is a file in the YAML format, which is a simple to read markup language. A full walkthrough of YAML is beyond the scope of this article, but you don't need to have an expert understanding of it to be proficient with Ansible. The configuration is easy to read; by simply looking at this file, you can easily glean that we're installing the `htop` package. Pay special attention to the `apt` module on the last line, which will only work on Debian-based systems. You can change this to `yum` instead of `apt` if you're using a Red Hat platform or change it to `dnf` if you're using Fedora. The `name` line simply gives information regarding our task and will be shown in the output. Therefore, you'll want to make sure the name is descriptive so it's easy to find if you need to troubleshoot multiple plays. - -Next, let's commit our new file to our repository: -``` -git add local.yml - -git commit -m "initial commit" - -git push origin master - -``` - -Now our new playbook should be present in our repository on GitHub. We can apply the playbook we created with the following command: -``` -sudo ansible-pull -U https://github.com/ /ansible.git - -``` - -If executed properly, the `htop` package should be installed on your system. You might've seen some warnings near the beginning that complain about the lack of an inventory file. This is fine, as we're not using an inventory file (nor do we need to for this use). At the end of the output, it will give you an overview of what it did. If `htop` was installed properly, you should see `changed=1` on the last line of the output. - -How did this work? The `ansible-pull` command uses the `-U` option, which expects a repository URL. I gave it the `https` version of the repository URL for security purposes because I don't want any hosts to have write access back to the repository (`https` is read-only by default). The `local.yml` playbook name is assumed, so we didn't need to provide a filename for the playbook—it will automatically run a playbook named `local.yml` if it finds it in the repository's root. Next, we used `sudo` in front of the command since we are modifying the system. - -Let's go ahead and add additional packages to our playbook. I'll add two additional packages so that it looks like this: -``` -- hosts: localhost - - become: true - - tasks: - - - name: Install htop - - apt: name=htop - - - - - name: Install mc - - apt: name=mc - - - - - name: Install tmux - - apt: name=tmux - -``` - -I added additional plays (tasks) for installing two other packages, `mc` and `tmux`. It doesn't matter what packages you choose to have this playbook install; I just picked these arbitrarily. You should install whichever packages you want all your systems to have. The only caveat is that you have to know that the packages exist in the repository for your distribution ahead of time. - -Before we commit and apply this updated playbook, we should clean it up. It will work fine as it is, but (to be honest) it looks kind of messy. Let's try installing all three packages in just one play. Replace the contents of your `local.yml` with this: -``` -- hosts: localhost - - become: true - - tasks: - - - name: Install packages - - apt: name={{item}} - - with_items: - - - htop - - - mc - - - tmux - -``` - -Now that looks cleaner and more efficient. We used `with_items` to consolidate our package list into one play. If we want to add additional packages, we simply add another line with a hyphen and a package name. Consider `with_items` to be similar to a `for` loop. Every package we list will be installed. - -Commit our new changes back to the repository: -``` -git add local.yml - -git commit -m "added additional packages, cleaned up formatting" - -git push origin master - -``` - -Now we can run our playbook to benefit from the new configuration: -``` -sudo ansible-pull -U https://github.com/ /ansible.git - -``` - -Admittedly, this example doesn't do much yet; all it does is install a few packages. You could've installed these packages much faster just using your package manager. However, as this series continues, these examples will become more complex and we'll automate more things. By the end, the Ansible configuration you'll create will automate more and more tasks. For example, the one I use automates the installation of hundreds of packages, sets up `cron` jobs, handles desktop configuration, and more. - -From what we've accomplished so far, you can probably already see the big picture. All we had to do was create a repository, put a playbook in that repository, then utilize the `ansible-pull` command to pull down that repository and apply it to our machine. We didn't need to set up a server. In the future, if we want to change our config, we can pull down the repo, update it, then push it back to our repository and apply it. If we're setting up a new machine, we only need to install Ansible and apply the configuration. - -In the next article, we'll automate this even further via `cron` and some additional items. In the meantime, I've copied the code for this article into [my GitHub repository][4] so you can check your syntax against mine. I'll update the code as we go along. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/3/manage-workstation-ansible - -作者：[Jay LaCroix][a] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://opensource.com/users/jlacroix -[1]:https://www.ansible.com/ -[2]:https://launchpad.net/ubuntu/+ppas -[3]:http://docs.ansible.com/ansible/latest/intro_installation.html -[4]:https://github.com/jlacroix82/ansible_article diff --git a/sources/tech/20180307 Protecting Code Integrity with PGP - Part 4- Moving Your Master Key to Offline Storage.md b/sources/tech/20180307 Protecting Code Integrity with PGP - Part 4- Moving Your Master Key to Offline Storage.md deleted file mode 100644 index df00e7e05e..0000000000 --- a/sources/tech/20180307 Protecting Code Integrity with PGP - Part 4- Moving Your Master Key to Offline Storage.md +++ /dev/null @@ -1,167 +0,0 @@ -Protecting Code Integrity with PGP — Part 4: Moving Your Master Key to Offline Storage -====== - - -In this tutorial series, we're providing practical guidelines for using PGP. You can catch up on previous articles here: - -[Part 1: Basic Concepts and Tools][1] - -[Part 2: Generating Your Master Key][2] - -[Part 3: Generating PGP Subkeys][3] - -Here in part 4, we continue the series with a look at how and why to move your master key from your home directory to offline storage. Let's get started. - -### Checklist - - * Prepare encrypted detachable storage (ESSENTIAL) - - * Back up your GnuPG directory (ESSENTIAL) - - * Remove the master key from your home directory (NICE) - - * Remove the revocation certificate from your home directory (NICE) - - - - -#### Considerations - -Why would you want to remove your master [C] key from your home directory? This is generally done to prevent your master key from being stolen or accidentally leaked. Private keys are tasty targets for malicious actors -- we know this from several successful malware attacks that scanned users' home directories and uploaded any private key content found there. - -It would be very damaging for any developer to have their PGP keys stolen -- in the Free Software world, this is often tantamount to identity theft. Removing private keys from your home directory helps protect you from such events. - -##### Back up your GnuPG directory - -**!!!Do not skip this step!!!** - -It is important to have a readily available backup of your PGP keys should you need to recover them (this is different from the disaster-level preparedness we did with paperkey). - -##### Prepare detachable encrypted storage - -Start by getting a small USB "thumb" drive (preferably two!) that you will use for backup purposes. You will first need to encrypt them: - -For the encryption passphrase, you can use the same one as on your master key. - -##### Back up your GnuPG directory - -Once the encryption process is over, re-insert the USB drive and make sure it gets properly mounted. Find out the full mount point of the device, for example by running the mount command (under Linux, external media usually gets mounted under /media/disk, under Mac it's /Volumes). - -Once you know the full mount path, copy your entire GnuPG directory there: -``` -$ cp -rp ~/.gnupg [/media/disk/name]/gnupg-backup - -``` - -(Note: If you get any Operation not supported on socket errors, those are benign and you can ignore them.) - -You should now test to make sure everything still works: -``` -$ gpg --homedir=[/media/disk/name]/gnupg-backup --list-key [fpr] - -``` - -If you don't get any errors, then you should be good to go. Unmount the USB drive and distinctly label it, so you don't blow it away next time you need to use a random USB drive. Then, put in a safe place -- but not too far away, because you'll need to use it every now and again for things like editing identities, adding or revoking subkeys, or signing other people's keys. - -##### Remove the master key - -The files in our home directory are not as well protected as we like to think. They can be leaked or stolen via many different means: - - * By accident when making quick homedir copies to set up a new workstation - - * By systems administrator negligence or malice - - * Via poorly secured backups - - * Via malware in desktop apps (browsers, pdf viewers, etc) - - * Via coercion when crossing international borders - - - - -Protecting your key with a good passphrase greatly helps reduce the risk of any of the above, but passphrases can be discovered via keyloggers, shoulder-surfing, or any number of other means. For this reason, the recommended setup is to remove your master key from your home directory and store it on offline storage. - -###### Removing your master key - -Please see the previous section and make sure you have backed up your GnuPG directory in its entirety. What we are about to do will render your key useless if you do not have a usable backup! - -First, identify the keygrip of your master key: -``` -$ gpg --with-keygrip --list-key [fpr] - -``` - -The output will be something like this: -``` -pub rsa4096 2017-12-06 [C] [expires: 2019-12-06] - 111122223333444455556666AAAABBBBCCCCDDDD - Keygrip = AAAA999988887777666655554444333322221111 -uid [ultimate] Alice Engineer /ansible.git - -``` - -If you recall, the `ansible-pull` command pulls down a Git repository and applies the configuration it contains. - -Now that our foundation is in place, we can expand upon our Ansible config and add features. Specifically, we'll add configuration to automate the deployment of future changes to our workstations. To support this goal, the first thing we should do is to create a user specifically to apply our Ansible configuration. This isn't required—we can continue to run our Ansible configuration under our own user. But using a separate user segregates this to a system process that will run in the background, without our involvement. - -We could create this user with the normal method, but since we're using Ansible, we should shy away from manual changes. Instead, we'll create a taskbook to handle user creation. This taskbook will create just one user for now, but you can always add additional plays to this taskbook to add additional users. I'll call this user `ansible`, but you can name it something else if you wish (if you do, make sure to update all occurrences). Let's create a taskbook named `users.yml` and place this code inside of it: -``` -- name: create ansible user - - user: name=ansible uid=900 - -``` - -Next, we need to edit our `local.yml` file and append this new taskbook to the file, so it will look like this: -``` -- hosts: localhost - - become: true - - pre_tasks: - - - name: update repositories - - apt: update_cache=yes - - changed_when: False - - - - tasks: - - - include: tasks/users.yml - - - include: tasks/packages.yml - -``` - -Now when we run our `ansible-pull` command, a user named `ansible` will be created on the system. Note that I specifically declared `User ID 900` for this user by using the `UID` option. This isn't required, but it's recommended. The reason is that UIDs under 1,000 are typically not shown on the login screen, which is great because there's no reason we would need to log into a desktop session as our `ansible` user. UID 900 is arbitrary; it should be any number under 1,000 that's not already in use. You can find out if UID 900 is in use on your system with the following command: -``` -cat /etc/passwd |grep 900 - -``` - -However, you shouldn't run into a problem with this UID because I've never seen it used by default in any distribution I've used so far. - -Now, we have an `ansible` user that will later be used to apply our Ansible configuration automatically. Next, we can create the actual cron job that will be used to automate this. Rather than place this in the `users.yml` taskbook we just created, we should separate this into its own file. Create a taskbook named `cron.yml` in the tasks directory and place the following code inside: -``` -- name: install cron job (ansible-pull) - - cron: user="ansible" name="ansible provision" minute="*/10" job="/usr/bin/ansible-pull -o -U https://github.com/ /ansible.git > /dev/null" - -``` - -The syntax for the cron module should be fairly self-explanatory. With this play, we're creating a cron job to be run as the `ansible` user. The job will execute every 10 minutes, and the command it will execute is this: -``` -/usr/bin/ansible-pull -o -U https://github.com/ /ansible.git > /dev/null - -``` - -Also, we can put additional cron jobs we want all our workstations to have into this one file. We just need to add additional plays to add new cron jobs. However, simply adding a new taskbook for cron isn't enough—we'll also need to add it to our `local.yml` file so it will be called. Place the following line with the other includes: -``` -- include: tasks/cron.yml - -``` - -Now when `ansible-pull` is run, it will set up a new cron job that will be run as the `ansible` user every 10 minutes. But, having an Ansible job running every 10 minutes isn't ideal because it will take considerable CPU power. It really doesn't make sense for Ansible to run every 10 minutes unless we've changed something in the Git repository. - -However, we've already solved this problem. Notice the `-o` option I added to the `ansible-pull` command in the cron job that we've never used before. This option tells Ansible to run only if the repository has changed since the last time `ansible-pull` was called. If the repository hasn't changed, it won't do anything. This way, you're not wasting valuable CPU for no reason. Sure, some CPU will be used when it pulls down the repository, but not nearly as much as it would use if it were applying your entire configuration all over again. When `ansible-pull` does run, it will go through all the tasks in the Playbook and taskbooks, but at least it won't run for no purpose. - -Although we've added all the required components to automate `ansible-pull`, it actually won't work properly yet. The `ansible-pull` command will run with `sudo`, which would give it access to perform system-level commands. However, our `ansible` user is not set up to perform tasks as `sudo`. Therefore, when the cron job triggers, it will fail. Normally we could just use `visudo` and manually set the `ansible` user up to have this access. However, we should do things the Ansible way from now on, and this is a great opportunity to show you how the `copy` module works. The `copy` module allows you to copy a file from your Ansible repository to somewhere else in the filesystem. In our case, we'll copy a config file for `sudo` to `/etc/sudoers.d/` so that the `ansible` user can perform administrative tasks. - -Open up the `users.yml` taskbook, and add the following play to the bottom: -``` -- name: copy sudoers_ansible - - copy: src=files/sudoers_ansible dest=/etc/sudoers.d/ansible owner=root group=root mode=0440 - -``` - -The `copy` module, as we can see, copies a file from our repository to somewhere else. In this case, we're grabbing a file named `sudoers_ansible` (which we will create shortly) and copying it to `/etc/sudoers.d/ansible` with `root` as the owner. - -Next, we need to create the file that we'll be copying. In the root of your Ansible repository, create a `files` directory: -``` -mkdir files - -``` - -Then, in the `files` directory we just created, create the `sudoers_ansible` file with the following content: -``` -ansible ALL=(ALL) NOPASSWD: ALL - -``` - -Creating a file in `/etc/sudoers.d`, like we're doing here, allows us to configure `sudo` for a specific user. Here we're allowing the `ansible` user full access to the system via `sudo` without a password prompt. This will allow `ansible-pull` to run as a background task without us needing to run it manually. - -Now, you can run `ansible-pull` again to pull down the latest changes: -``` -sudo ansible-pull -U https://github.com/ /ansible.git - -``` - -From this point forward, the cron job for `ansible-pull` will run every 10 minutes in the background and check your repository for changes. If it finds changes, it will run your playbook and apply your taskbooks. - -So now we have a fully working solution. When you first set up a new laptop or desktop, you'll run the `ansible-pull` command manually, but only the first time. From that point forward, the `ansible` user will take care of subsequent runs in the background. When you want to make a change to your workstation machines, you simply pull down your Git repository, make the changes, then push those changes back to the repository. Then, the next time the cron job fires on each machine, it will pull down those changes and apply them. You now only have to make changes once, and all your workstations will follow suit. This method may be a bit unconventional though. Normally, you'd have an `inventory` file with your machines listed and several roles each machine could be a member of. However, the `ansible-pull` method, as described in this article, is a very efficient way of managing workstation configuration. - -I have updated the code in my [GitHub repository][2] for this article, so feel free to browse the code there and check your syntax against mine. Also, I moved the code from the previous article into its own directory in that repository. - -In part 3, we'll close out the series by using Ansible to configure GNOME desktop settings. I'll show you how to set your wallpaper and lock screen, apply a desktop theme, and more. - -In the meantime, it's time for a little homework assignment. Most of us have configuration files we like to maintain for various applications we use. This could be configuration files for Bash, Vim, or whatever tools you use. I challenge you now to automate copying these configuration files to your machines via the Ansible repository we've been working on. In this article, I've shown you how to copy a file, so take a look at that and see if you can apply that knowledge to your personal files. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/3/manage-your-workstation-configuration-ansible-part-2 - -作者：[Jay LaCroix][a] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) -选题：[lujun9972](https://github.com/lujun9972) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://opensource.com/users/jlacroix -[1]:https://opensource.com/article/18/3/manage-workstation-ansible -[2]:https://github.com/jlacroix82/ansible_article.git diff --git a/sources/tech/20180328 What NASA Has Been Doing About Open Science.md b/sources/tech/20180328 What NASA Has Been Doing About Open Science.md deleted file mode 100644 index 96d3aaa4a0..0000000000 --- a/sources/tech/20180328 What NASA Has Been Doing About Open Science.md +++ /dev/null @@ -1,114 +0,0 @@ -What NASA Has Been Doing About Open Science -====== -![][1] - -We have recently started a new [Science category][2] on It’s FOSS. We covered [how open source approach is impacting Science][3] in the last article. In this open science article, we discuss [NASA][4]‘s actively growing efforts that involve their dynamic role in boosting scientific research by encouraging open source practices. - -### How NASA is using Open Source approach to improve science - -It was a great [initiative][5] by NASA that they made their entire research library freely available on the public domain. - -Yes! Entire research library for everyone to access and get benefit from it in their research. - -Their open science resources can now be mainly classified into these three categories as follows: - - * Open Source NASA - * Open API - * Open Data - - - -#### 1\. Open Source NASA - -Here’s an interesting interview of [Chris Wanstrath][6], co-founder and CEO of [GitHub][7], about how it all began to form many years ago: - -Uniquely named “[code.nasa.gov][8]“, NASA now has precisely 365 scientific software available as [open source via GitHub][9] as of the time of this post. So if you are a developer who loves coding, you can study each one of them every day for a year’s time! - -Even if you are not a developer, you can still browse through the fantastic collection of open source packages enlisted on the portal! - -One of the interesting open source packages listed here is the source code of [Apollo 11][10]‘s guidance computer. The Apollo 11 spaceflight took [the first two humans to the Moon][11], namely, [Neil Armstrong][12] and [Edwin Aldrin][13] ! If you want to know more about Edwin Aldrin, you might want to pay a visit [here][14]. - -##### Licenses being used by NASA’s Open Source Initiative: - -Here are the different [open source licenses][15] categorized as under: - -#### 2\. Open API - -An Open [Application Programming Interface][16] or API plays a significant role in practicing Open Science. Just like [The Open Source Initiative][17], there is also one for API, called [The Open API Initiative][18]. Here is a simple illustration of how an API bridges an application with its developer: - -![][19] - -Do check out the link in the caption in the image above. The API has been explained in a straightforward manner. It concludes with five exciting takeaways in the end. - -![][20] - -Makes one wonder how different [an open vs a proprietary API][21] would be. - -![][22] - -Targeted towards application developers, [NASA’s open API][23] is an initiative to significantly improve the accessibility of data that could also contain image content. The site has a live editor, allowing you check out the [API][16] behind [Astronomy Picture of the Day (APOD)][24]. - -#### 3\. Open Data - -![][25] - -In [our first science article][3], we shared with you the various open data models of three countries mentioned under the “Open Science” section, namely, France, India and the U.S. NASA also has a similar approach towards the same idea. This is a very important ideology that is being adopted by [many countries][26]. - -[NASA’s Open Data Portal][27] focuses on openness by having an ever-growing catalog of data, available for anyone to access freely. The inclusion of datasets within this collection is an essential and radical step towards the development of research of any kind. NASA have even taken a fantastic initiative to ask for dataset suggestions for submission on their portal and that’s really very innovative, considering the growing trends of [data science][28], [AI and deep learning][29]. - -The following video shows students and scientists coming up with their own definitions of Data Science based on their personal experience and research. That is really encouraging! [Dr. Murtaza Haider][30], Ted Rogers School of Management, Ryerson University, mentions the difference Open Source is making in the field of Data Science before the video ends. He explains in very simple terms, how development models transitioned from a closed source approach to an open one. The vision has proved to be sufficiently true enough in today’s time. - -![][31] - -Now anyone can suggest a dataset of any kind on NASA. Coming back to the video above, NASA’s initiative can be related so much with submitting datasets and working on analyzing them for better Data Science! - -![][32] - -You just need to signup for free. This initiative will have a very positive effect in the future, considering open discussions on the public forum and the significance of datasets in every type of analytical field that could exist. Statistical studies will also significantly improve for sure. We will talk about these concepts in detail in a future article and also about their relativeness to an open source model. - -So thus concludes an exploration into NASA’s open science model. See you soon in another open science article! - --------------------------------------------------------------------------------- - -via: https://itsfoss.com/nasa-open-science/ - -作者：[Avimanyu Bandyopadhyay][a] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) -选题：[lujun9972](https://github.com/lujun9972) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://itsfoss.com/author/avimanyu/ -[1]:https://itsfoss.com/wp-content/uploads/2018/03/tux-in-space.jpg -[2]:https://itsfoss.com/category/science/ -[3]:https://itsfoss.com/open-source-impact-on-science/ -[4]:https://www.nasa.gov/ -[5]:https://futurism.com/free-science-nasa-just-opened-its-entire-research-library-to-the-public/ -[6]:http://chriswanstrath.com/ -[7]:https://github.com/ -[8]:http://code.nasa.gov -[9]:https://github.com/open-source -[10]:https://www.nasa.gov/mission_pages/apollo/missions/apollo11.html -[11]:https://www.space.com/16758-apollo-11-first-moon-landing.html -[12]:https://www.jsc.nasa.gov/Bios/htmlbios/armstrong-na.html -[13]:https://www.jsc.nasa.gov/Bios/htmlbios/aldrin-b.html -[14]:https://buzzaldrin.com/the-man/ -[15]:https://itsfoss.com/open-source-licenses-explained/ -[16]:https://en.wikipedia.org/wiki/Application_programming_interface -[17]:https://opensource.org/ -[18]:https://www.openapis.org/ -[19]:https://itsfoss.com/wp-content/uploads/2018/03/api-bridge.jpeg -[20]:https://itsfoss.com/wp-content/uploads/2018/03/open-api-diagram.jpg -[21]:http://www.apiacademy.co/resources/api-strategy-lesson-201-private-apis-vs-open-apis/ -[22]:https://itsfoss.com/wp-content/uploads/2018/03/nasa-open-api-live-example.jpg -[23]:https://api.nasa.gov/ -[24]:https://apod.nasa.gov/apod/astropix.html -[25]:https://itsfoss.com/wp-content/uploads/2018/03/nasa-open-data-portal.jpg -[26]:https://www.xbrl.org/the-standard/why/ten-countries-with-open-data/ -[27]:https://data.nasa.gov/ -[28]:https://en.wikipedia.org/wiki/Data_science -[29]:https://www.kdnuggets.com/2017/07/ai-deep-learning-explained-simply.html -[30]:https://www.ryerson.ca/tedrogersschool/bm/programs/real-estate-management/murtaza-haider/ -[31]:https://itsfoss.com/wp-content/uploads/2018/03/suggest-dataset-nasa-1.jpg -[32]:https://itsfoss.com/wp-content/uploads/2018/03/suggest-dataset-nasa-2-1.jpg diff --git a/sources/tech/20180331 Emacs -4- Automated emails to org-mode and org-mode syncing.md b/sources/tech/20180331 Emacs -4- Automated emails to org-mode and org-mode syncing.md deleted file mode 100644 index 4efe606f51..0000000000 --- a/sources/tech/20180331 Emacs -4- Automated emails to org-mode and org-mode syncing.md +++ /dev/null @@ -1,72 +0,0 @@ -Emacs #4: Automated emails to org-mode and org-mode syncing -====== -This is fourth in [a series on Emacs and org-mode][1]. - -Hopefully by now you’ve started to see how powerful and useful org-mode is. If you’re like me, you’re thinking: - -“I’d really like to have this in sync across all my devices.” - -and, perhaps: - -“Can I forward emails into org-mode?” - -This being Emacs, the answers, of course, are “Yes.” - -### Syncing - -Since org-mode just uses text files, syncing is pretty easily accomplished using any number of tools. I use git with git-remote-gcrypt. Due to some limitations of git-remote-gcrypt, each machine tends to push to its own branch, and to master on command. Each machine merges from all the other branches and pushes the result to master after a merge. A cron job causes pushes to the machine’s branch to happen, and a bit of elisp coordinates it all — making sure to save buffers before a sync, refresh them from disk after, etc. - -The code for this post is somewhat more extended, so I will be linking to it on github rather than posting inline. - -I have a directory $HOME/org where all my org-stuff lives. In ~/org lives [a Makefile][2] that handles the syncing. It defines these targets: - - * push: adds, commits, and pushes to a branch named after the machine’s hostname - * fetch: does a simple git fetch - * sync: adds, commits, pulls remote changes, merges, and (assuming the merge was successful) pushes to the branch named after the machine’s hostname plus master - - - -Now, in my user’s crontab, I have this: -``` -*/15 * * * * make -C $HOME/org push fetch 2>&1 | logger --tag 'orgsync' - -``` - -The [accompanying elisp code][3] defines a shortcut (C-c s) to cause a sync to occur. Thanks to the cronjob, as long as files were saved — even if I didn’t explicitly sync on the other boxen — they’ll be pulled in. - -I have found this setup to work really well. - -### Emailing to org-mode - -Before going down this path, one should ask the question: do you really need it? I use org-mode with mu4e, and the integration is excellent; any org task can link to an email by message-id, and this is ideal — it lets a person do things like make a reminder to reply to a message in a week. - -However, org is not just about reminders. It’s also a knowledge base, authoring system, etc. And, not all of my mail clients use mu4e. (Note: things like MobileOrg exist for mobile devices). I don’t actually use this as much as I thought I would, but it has its uses and I thought I’d document it here too. - -Now I didn’t want to just be able to accept plain text email. I wanted to be able to handle attachments, HTML mail, etc. This quickly starts to sound problematic — but with tools like ripmime and pandoc, it’s not too bad. - -The first step is to set up some way to get mail into a specific folder. A plus-extension, special user, whatever. I then use a [fetchmail configuration][4] to pull it down and run my [insorgmail][5] script. - -This script is where all the interesting bits happen. It starts with ripmime to process the message. HTML bits are converted from HTML to org format using pandoc. an org hierarchy is made to represent the structure of the email as best as possible. emails can get pretty complicated, with HTML and the rest, but I have found this does an acceptable job with my use cases. - -### Up next… - -My last post on org-mode will talk about using it to write documents and prepare slides — a use for which I found myself surprisingly pleased with it, but which needed a bit of tweaking. - - - --------------------------------------------------------------------------------- - -via: http://changelog.complete.org/archives/9898-emacs-4-automated-emails-to-org-mode-and-org-mode-syncing - -作者：[John Goerzen][a] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:http://changelog.complete.org/ -[1]:https://changelog.complete.org/archives/tag/emacs2018 -[2]:https://github.com/jgoerzen/public-snippets/blob/master/emacs/org-tools/Makefile -[3]:https://github.com/jgoerzen/public-snippets/blob/master/emacs/org-tools/emacs-config.org -[4]:https://github.com/jgoerzen/public-snippets/blob/master/emacs/org-tools/fetchmailrc.orgmail -[5]:https://github.com/jgoerzen/public-snippets/blob/master/emacs/org-tools/insorgmail diff --git a/sources/tech/20180402 An introduction to the Flask Python web app framework.md b/sources/tech/20180402 An introduction to the Flask Python web app framework.md new file mode 100644 index 0000000000..ffb6e9c441 --- /dev/null +++ b/sources/tech/20180402 An introduction to the Flask Python web app framework.md @@ -0,0 +1,451 @@ +[#]: collector: (lujun9972) +[#]: translator: (fuowang) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: subject: (An introduction to the Flask Python web app framework) +[#]: via: (https://opensource.com/article/18/4/flask) +[#]: author: (Nicholas Hunt-Walker https://opensource.com/users/nhuntwalker) +[#]: url: ( ) + +An introduction to the Flask Python web app framework +====== +In the first part in a series comparing Python frameworks, learn about Flask. + + +If you're developing a web app in Python, chances are you're leveraging a framework. A [framework][1] "is a code library that makes a developer's life easier when building reliable, scalable, and maintainable web applications" by providing reusable code or extensions for common operations. There are a number of frameworks for Python, including [Flask][2], [Tornado][3], [Pyramid][4], and [Django][5]. New Python developers often ask: Which framework should I use? + + * New visitors to the site should be able to register new accounts. + * Registered users can log in, log out, see information for their profiles, and edit their information. + * Registered users can create new task items, see their existing tasks, and edit existing tasks. + + + +This series is designed to help developers answer that question by comparing those four frameworks. To compare their features and operations, I'll take each one through the process of constructing an API for a simple To-Do List web application. The API is itself fairly straightforward: + +All this rounds out to a compact set of API endpoints that each backend must implement, along with the allowed HTTP methods: + + * `GET /` + * `POST /accounts` + * `POST /accounts/login` + * `GET /accounts/logout` + * `GET, PUT, DELETE /accounts/ ` + * `GET, POST /accounts/ /tasks` + * `GET, PUT, DELETE /accounts/ /tasks/ ` + + + +Each framework has a different way to put together its routes, models, views, database interaction, and overall application configuration. I'll describe those aspects of each framework in this series, which will begin with Flask. + +### Flask startup and configuration + +Like most widely used Python libraries, the Flask package is installable from the [Python Package Index][6] (PPI). First create a directory to work in (something like `flask_todo` is a fine directory name) then install the `flask` package. You'll also want to install `flask-sqlalchemy` so your Flask application has a simple way to talk to a SQL database. + +I like to do this type of work within a Python 3 virtual environment. To get there, enter the following on the command line: + +``` +$ mkdir flask_todo +$ cd flask_todo +$ pipenv install --python 3.6 +$ pipenv shell +(flask-someHash) $ pipenv install flask flask-sqlalchemy +``` + +If you want to turn this into a Git repository, this is a good place to run `git init`. It'll be the root of the project, and if you want to export the codebase to a different machine, it will help to have all the necessary setup files here. + +A good way to get moving is to turn the codebase into an installable Python distribution. At the project's root, create `setup.py` and a directory called `todo` to hold the source code. + +The `setup.py` should look something like this: + +``` +from setuptools import setup, find_packages + +requires = [ + 'flask', + 'flask-sqlalchemy', + 'psycopg2', +] + +setup( + name='flask_todo', + version='0.0', + description='A To-Do List built with Flask', + author=' ', + author_email=' ', + keywords='web flask', + packages=find_packages(), + include_package_data=True, + install_requires=requires +) +``` + +This way, whenever you want to install or deploy your project, you'll have all the necessary packages in the `requires` list. You'll also have everything you need to set up and install the package in `site-packages`. For more information on how to write an installable Python distribution, check out [the docs on setup.py][7]. + +Within the `todo` directory containing your source code, create an `app.py` file and a blank `__init__.py` file. The `__init__.py` file allows you to import from `todo` as if it were an installed package. The `app.py` file will be the application's root. This is where all the `Flask` application goodness will go, and you'll create an environment variable that points to that file. If you're using `pipenv` (like I am), you can locate your virtual environment with `pipenv --venv` and set up that environment variable in your environment's `activate` script. + +``` +# in your activate script, probably at the bottom (but anywhere will do) + +export FLASK_APP=$VIRTUAL_ENV/../todo/app.py +export DEBUG='True' +``` + +When you installed `Flask`, you also installed the `flask` command-line script. Typing `flask run` will prompt the virtual environment's Flask package to run an HTTP server using the `app` object in whatever script the `FLASK_APP` environment variable points to. The script above also includes an environment variable named `DEBUG` that will be used a bit later. + +Let's talk about this `app` object. + +In `todo/app.py`, you'll create an `app` object, which is an instance of the `Flask` object. It'll act as the central configuration object for the entire application. It's used to set up pieces of the application required for extended functionality, e.g., a database connection and help with authentication. + +It's regularly used to set up the routes that will become the application's points of interaction. To explain what this means, let's look at the code it corresponds to. + +``` +from flask import Flask + +app = Flask(__name__) + +@app.route('/') +def hello_world(): + """Print 'Hello, world!' as the response body.""" + return 'Hello, world!' +``` + +This is the most basic complete Flask application. `app` is an instance of `Flask`, taking in the `__name__` of the script file. This lets Python know how to import from files relative to this one. The `app.route` decorator decorates the first **view** function; it can specify one of the routes used to access the application. (We'll look at this later.) + +Any view you specify must be decorated by `app.route` to be a functional part of the application. You can have as many functions as you want scattered across the application, but in order for that functionality to be accessible from anything external to the application, you must decorate that function and specify a route to make it into a view. + +In the example above, when the app is running and accessed at `http://domainname/`, a user will receive `"Hello, World!"` as a response. + +### Connecting the database in Flask + +While the code example above represents a complete Flask application, it doesn't do anything interesting. One interesting thing a web application can do is persist user data, but it needs the help of and connection to a database. + +Flask is very much a "do it yourself" web framework. This means there's no built-in database interaction, but the `flask-sqlalchemy` package will connect a SQL database to a Flask application. The `flask-sqlalchemy` package needs just one thing to connect to a SQL database: The database URL. + +Note that a wide variety of SQL database management systems can be used with `flask-sqlalchemy`, as long as the DBMS has an intermediary that follows the [DBAPI-2 standard][8]. In this example, I'll use PostgreSQL (mainly because I've used it a lot), so the intermediary to talk to the Postgres database is the `psycopg2` package. Make sure `psycopg2` is installed in your environment and include it in the list of required packages in `setup.py`. You don't have to do anything else with it; `flask-sqlalchemy` will recognize Postgres from the database URL. + +Flask needs the database URL to be part of its central configuration through the `SQLALCHEMY_DATABASE_URI` attribute. A quick and dirty solution is to hardcode a database URL into the application. + +``` +# top of app.py +from flask import Flask +from flask_sqlalchemy import SQLAlchemy + +app = Flask(__name__) +app.config['SQLALCHEMY_DATABASE_URI'] = 'postgres://localhost:5432/flask_todo' +db = SQLAlchemy(app) +``` + +However, this is not a sustainable solution. If you change databases or don't want your database URL visible in source control, you'll have to take extra steps to ensure your information is appropriate for the environment. + +You can make things simpler by using environment variables. They will ensure that, no matter what machine the code runs on, it always points at the right stuff if that stuff is configured in the running environment. It also ensures that, even though you need that information to run the application, it never shows up as a hardcoded value in source control. + +In the same place you declared `FLASK_APP`, declare a `DATABASE_URL` pointing to the location of your Postgres database. Development tends to work locally, so just point to your local database. + +``` +# also in your activate script + +export DATABASE_URL='postgres://localhost:5432/flask_todo' +``` + +Now in `app.py`, include the database URL in your app configuration. + +``` +app.config['SQLALCHEMY_DATABASE_URI'] = os.environ.get('DATABASE_URL', '') +db = SQLAlchemy(app) +``` + +And just like that, your application has a database connection! + +### Defining objects in Flask + +Having a database to talk to is a good first step. Now it's time to define some objects to fill that database. + +In application development, a "model" refers to the data representation of some real or conceptual object. For example, if you're building an application for a car dealership, you may define a `Car` model that encapsulates all of a car's attributes and behavior. + +In this case, you're building a To-Do List with Tasks, and each Task belongs to a User. Before you think too deeply about how they're related to each other, start by defining objects for Tasks and Users. + +The `flask-sqlalchemy` package leverages [SQLAlchemy][9] to set up and inform the database structure. You'll define a model that will live in the database by inheriting from the `db.Model` object and define the attributes of those models as `db.Column` instances. For each column, you must specify a data type, so you'll pass that data type into the call to `db.Column` as the first argument. + +Because the model definition occupies a different conceptual space than the application configuration, make `models.py` to hold model definitions separate from `app.py`. The Task model should be constructed to have the following attributes: + + * `id`: a value that's a unique identifier to pull from the database + * `name`: the name or title of the task that the user will see when the task is listed + * `note`: any extra comments that a person might want to leave with their task + * `creation_date`: the date and time the task was created + * `due_date`: the date and time the task is due to be completed (if at all) + * `completed`: a way to indicate whether or not the task has been completed + + + +Given this attribute list for Task objects, the application's `Task` object can be defined like so: + +``` +from .app import db +from datetime import datetime + +class Task(db.Model): + """Tasks for the To Do list.""" + id = db.Column(db.Integer, primary_key=True) + name = db.Column(db.Unicode, nullable=False) + note = db.Column(db.Unicode) + creation_date = db.Column(db.DateTime, nullable=False) + due_date = db.Column(db.DateTime) + completed = db.Column(db.Boolean, default=False) + + def __init__(self, *args, **kwargs): + """On construction, set date of creation.""" + super().__init__(*args, **kwargs) + self.creation_date = datetime.now() +``` + +Note the extension of the class constructor method. At the end of the day, any model you construct is still a Python object and therefore must go through construction in order to be instantiated. It's important to ensure that the creation date of the model instance reflects its actual date of creation. You can explicitly set that relationship by effectively saying, "when an instance of this model is constructed, record the date and time and set it as the creation date." + +### Model relationships + +In a given web application, you may want to be able to express relationships between objects. In the To-Do List example, users own multiple tasks, and each task is owned by only one user. This is an example of a "many-to-one" relationship, also known as a foreign key relationship, where the tasks are the "many" and the user owning those tasks is the "one." + +In Flask, a many-to-one relationship can be specified using the `db.relationship` function. First, build the User object. + +``` +class User(db.Model): + """The User object that owns tasks.""" + id = db.Column(db.Integer, primary_key=True) + username = db.Column(db.Unicode, nullable=False) + email = db.Column(db.Unicode, nullable=False) + password = db.Column(db.Unicode, nullable=False) + date_joined = db.Column(db.DateTime, nullable=False) + token = db.Column(db.Unicode, nullable=False) + + def __init__(self, *args, **kwargs): + """On construction, set date of creation.""" + super().__init__(*args, **kwargs) + self.date_joined = datetime.now() + self.token = secrets.token_urlsafe(64) +``` + +It looks very similar to the Task object; you'll find that most objects have the same basic format of class attributes as table columns. Every once in a while, you'll run into something a little different, including some multiple-inheritance magic, but this is the norm. + +Now that the `User` model is created, you can set up the foreign key relationship. For the "many," set fields for the `user_id` of the `User` that owns this task, as well as the `user` object with that ID. Also make sure to include a keyword argument (`back_populates`) that updates the User model when the task gets a user as an owner. + +For the "one," set a field for the `tasks` the specific user owns. Similar to maintaining the two-way relationship on the Task object, set a keyword argument on the User's relationship field to update the Task when it is assigned to a user. + +``` +# on the Task object +user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False) +user = db.relationship("user", back_populates="tasks") + +# on the User object +tasks = db.relationship("Task", back_populates="user") +``` + +### Initializing the database + +Now that the models and model relationships are set, start setting up your database. Flask doesn't come with its own database-management utility, so you'll have to write your own (to some degree). You don't have to get fancy with it; you just need something to recognize what tables are to be created and some code to create them (or drop them should the need arise). If you need something more complex, like handling updates to database tables (i.e., database migrations), you'll want to look into a tool like [Flask-Migrate][10] or [Flask-Alembic][11]. + +Create a script called `initializedb.py` next to `setup.py` for managing the database. (Of course, it doesn't need to be called this, but why not give names that are appropriate to a file's function?) Within `initializedb.py`, import the `db` object from `app.py` and use it to create or drop tables. `initializedb.py` should end up looking something like this: + +``` +from todo.app import db +import os + +if bool(os.environ.get('DEBUG', '')): + db.drop_all() +db.create_all() +``` + +If a `DEBUG` environment variable is set, drop tables and rebuild. Otherwise, just create the tables once and you're good to go. + +### Views and URL config + +The last bits needed to connect the entire application are the views and routes. In web development, a "view" (in concept) is functionality that runs when a specific access point (a "route") in your application is hit. These access points appear as URLs: paths to functionality in an application that return some data or handle some data that has been provided. The views will be logical structures that handle specific HTTP requests from a given client and return some HTTP response to that client. + +In Flask, views appear as functions; for example, see the `hello_world` view above. For simplicity, here it is again: + +``` +@app.route('/') +def hello_world(): + """Print 'Hello, world!' as the response body.""" + return 'Hello, world!' +``` + +When the route of `http://domainname/` is accessed, the client receives the response, "Hello, world!" + +With Flask, a function is marked as a view when it is decorated by `app.route`. In turn, `app.route` adds to the application's central configuration a map from the specified route to the function that runs when that route is accessed. You can use this to start building out the rest of the API. + +Start with a view that handles only `GET` requests, and respond with the JSON representing all the routes that will be accessible and the methods that can be used to access them. + +``` +from flask import jsonify + +@app.route('/api/v1', methods=["GET"]) +def info_view(): + """List of routes for this API.""" + output = { + 'info': 'GET /api/v1', + 'register': 'POST /api/v1/accounts', + 'single profile detail': 'GET /api/v1/accounts/ ', + 'edit profile': 'PUT /api/v1/accounts/ ', + 'delete profile': 'DELETE /api/v1/accounts/ ', + 'login': 'POST /api/v1/accounts/login', + 'logout': 'GET /api/v1/accounts/logout', + "user's tasks": 'GET /api/v1/accounts/ /tasks', + "create task": 'POST /api/v1/accounts/ /tasks', + "task detail": 'GET /api/v1/accounts/ /tasks/ ', + "task update": 'PUT /api/v1/accounts/ /tasks/ ', + "delete task": 'DELETE /api/v1/accounts/ /tasks/ ' + } + return jsonify(output) +``` + +Since you want your view to handle one specific type of HTTP request, use `app.route` to add that restriction. The `methods` keyword argument will take a list of strings as a value, with each string a type of possible HTTP method. In practice, you can use `app.route` to restrict to one or more types of HTTP request or accept any by leaving the `methods` keyword argument alone. + +Whatever you intend to return from your view function **must** be a string or an object that Flask turns into a string when constructing a properly formatted HTTP response. The exceptions to this rule are when you're trying to handle redirects and exceptions thrown by your application. What this means for you, the developer, is that you need to be able to encapsulate whatever response you're trying to send back to the client into something that can be interpreted as a string. + +A good structure that contains complexity but can still be stringified is a Python dictionary. Therefore, I recommend that, whenever you want to send some data to the client, you choose a Python `dict` with whatever key-value pairs you need to convey information. To turn that dictionary into a properly formatted JSON response, headers and all, pass it as an argument to Flask's `jsonify` function (`from flask import jsonify`). + +The view function above takes what is effectively a listing of every route that this API intends to handle and sends it to the client whenever the `http://domainname/api/v1` route is accessed. Note that, on its own, Flask supports routing to exactly matching URIs, so accessing that same route with a trailing `/` would create a 404 error. If you wanted to handle both with the same view function, you'd need stack decorators like so: + +``` +@app.route('/api/v1', methods=["GET"]) +@app.route('/api/v1/', methods=["GET"]) +def info_view(): + # blah blah blah more code +``` + +An interesting case is that if the defined route had a trailing slash and the client asked for the route without the slash, you wouldn't need to double up on decorators. Flask would redirect the client's request appropriately. It's odd that it doesn't work both ways. + +### Flask requests and the DB + +At its base, a web framework's job is to handle incoming HTTP requests and return HTTP responses. The previously written view doesn't really have much to do with HTTP requests aside from the URI that was accessed. It doesn't process any data. Let's look at how Flask behaves when data needs handling. + +The first thing to know is that Flask doesn't provide a separate `request` object to each view function. It has **one** global request object that every view function can use, and that object is conveniently named `request` and is importable from the Flask package. + +The next thing is that Flask's route patterns can have a bit more nuance. One scenario is a hardcoded route that must be matched perfectly to activate a view function. Another scenario is a route pattern that can handle a range of routes, all mapping to one view by allowing a part of that route to be variable. If the route in question has a variable, the corresponding value can be accessed from the same-named variable in the view's parameter list. + +``` +@app.route('/a/sample/ /route) +def some_view(variable): + # some code blah blah blah +``` + +To communicate with the database within a view, you must use the `db` object that was populated toward the top of the script. Its `session` attribute is your connection to the database when you want to make changes. If you just want to query for objects, the objects built from `db.Model` have their own database interaction layer through the `query` attribute. + +Finally, any response you want from a view that's more complex than a string must be built deliberately. Previously you built a response using a "jsonified" dictionary, but certain assumptions were made (e.g., 200 status code, status message "OK," Content-Type of "text/plain"). Any special sauce you want in your HTTP response must be added deliberately. + +Knowing these facts about working with Flask views allows you to construct a view whose job is to create new `Task` objects. Let's look at the code (below) and address it piece by piece. + +``` +from datetime import datetime +from flask import request, Response +from flask_sqlalchemy import SQLAlchemy +import json + +from .models import Task, User + +app = Flask(__name__) +app.config['SQLALCHEMY_DATABASE_URI'] = os.environ.get('DATABASE_URL', '') +db = SQLAlchemy(app) + +INCOMING_DATE_FMT = '%d/%m/%Y %H:%M:%S' + +@app.route('/api/v1/accounts/ /tasks', methods=['POST']) +def create_task(username): + """Create a task for one user.""" + user = User.query.filter_by(username=username).first() + if user: + task = Task( + name=request.form['name'], + note=request.form['note'], + creation_date=datetime.now(), + due_date=datetime.strptime(due_date, INCOMING_DATE_FMT) if due_date else None, + completed=bool(request.form['completed']), + user_id=user.id, + ) + db.session.add(task) + db.session.commit() + output = {'msg': 'posted'} + response = Response( + mimetype="application/json", + response=json.dumps(output), + status=201 + ) + return response +``` + +Let's start with the `@app.route` decorator. The route is `'/api/v1/accounts/ /tasks'`, where ` ` is a route variable. Put angle brackets around any part of the route you want to be variable, then include that part of the route on the next line in the parameter list **with the same name**. The only parameters that should be in the parameter list should be the variables in your route. + +Next comes the query: + +``` +user = User.query.filter_by(username=username).first() +``` + +To look for one user by username, conceptually you need to look at all the User objects stored in the database and find the users with the username matching the one that was requested. With Flask, you can ask the `User` object directly through the `query` attribute for the instance matching your criteria. This type of query would provide a list of objects (even if it's only one object or none at all), so to get the object you want, just call `first()`. + +``` +task = Task( + name=request.form['name'], + note=request.form['note'], + creation_date=datetime.now(), + due_date=datetime.strptime(due_date, INCOMING_DATE_FMT) if due_date else None, + completed=bool(request.form['completed']), + user_id=user.id, +) +``` + +Whenever data is sent to the application, regardless of the HTTP method used, that data is stored on the `form` attribute of the `request` object. The name of the field on the frontend will be the name of the key mapped to that data in the `form` dictionary. It'll always come in the form of a string, so if you want your data to be a specific data type, you'll have to make it explicit by casting it as the appropriate type. + +The other thing to note is the assignment of the current user's user ID to the newly instantiated `Task`. This is how that foreign key relationship is maintained. + +``` +db.session.add(task) +db.session.commit() +``` + +Creating a new `Task` instance is great, but its construction has no inherent connection to tables in the database. In order to insert a new row into the corresponding SQL table, you must use the `session` attached to the `db` object. The `db.session.add(task)` stages the new `Task` instance to be added to the table, but doesn't add it yet. While it's done only once here, you can add as many things as you want before committing. The `db.session.commit()` takes all the staged changes, or "commits," and applies them to the corresponding tables in the database. + +``` +output = {'msg': 'posted'} +response = Response( + mimetype="application/json", + response=json.dumps(output), + status=201 +) +``` + +The response is an actual instance of a `Response` object with its `mimetype`, body, and `status` set deliberately. The goal for this view is to alert the user they created something new. Seeing how this view is supposed to be part of a backend API that sends and receives JSON, the response body must be JSON serializable. A dictionary with a simple string message should suffice. Ensure that it's ready for transmission by calling `json.dumps` on your dictionary, which will turn your Python object into valid JSON. This is used instead of `jsonify`, as `jsonify` constructs an actual response object using its input as the response body. In contrast, `json.dumps` just takes a given Python object and converts it into a valid JSON string if possible. + +By default, the status code of any response sent with Flask will be `200`. That will work for most circumstances, where you're not trying to send back a specific redirection-level or error-level message. Since this case explicitly lets the frontend know when a new item has been created, set the status code to be `201`, which corresponds to creating a new thing. + +And that's it! That's a basic view for creating a new `Task` object in Flask given the current setup of your To-Do List application. Similar views could be constructed for listing, editing, and deleting tasks, but this example offers an idea of how it could be done. + +### The bigger picture + +There is much more that goes into an application than one view for creating new things. While I haven't discussed anything about authorization/authentication systems, testing, database migration management, cross-origin resource sharing, etc., the details above should give you more than enough to start digging into building your own Flask applications. + +Learn more Python at [PyCon Cleveland 2018][12]. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/4/flask + +作者：[Nicholas Hunt-Walker][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/nhuntwalker +[b]: https://github.com/lujun9972 +[1]: https://www.fullstackpython.com/web-frameworks.html +[2]: http://flask.pocoo.org/ +[3]: http://www.tornadoweb.org/en/stable/ +[4]: https://trypyramid.com/ +[5]: https://www.djangoproject.com/ +[6]: https://pypi.python.org +[7]: https://docs.python.org/3/distutils/setupscript.html +[8]: https://www.python.org/dev/peps/pep-0249/ +[9]: https://www.sqlalchemy.org/ +[10]: https://flask-migrate.readthedocs.io/en/latest/ +[11]: https://flask-alembic.readthedocs.io/en/stable/ +[12]: https://us.pycon.org/2018/ diff --git a/sources/tech/20180404 Emacs -5- Documents and Presentations with org-mode.md b/sources/tech/20180404 Emacs -5- Documents and Presentations with org-mode.md deleted file mode 100644 index 06c8dc8856..0000000000 --- a/sources/tech/20180404 Emacs -5- Documents and Presentations with org-mode.md +++ /dev/null @@ -1,177 +0,0 @@ -Emacs #5: Documents and Presentations with org-mode -====== - -### 1 About org-mode exporting - -#### 1.1 Background - -org-mode isn't just an agenda-making program. It can also export to lots of formats: LaTeX, PDF, Beamer, iCalendar (agendas), HTML, Markdown, ODT, plain text, man pages, and more complicated formats such as a set of web pages. - -This isn't just some afterthought either; it's a core part of the system and integrates very well. - -One file can be source code, automatically-generated output, task list, documentation, and presentation, all at once. - -Some use org-mode as their preferred markup format, even for things like LaTeX documents. The org-mode manual has an extensive [section on exporting][13]. - -#### 1.2 Getting started - -From any org-mode document, just hit C-c C-e. From there will come up a menu, letting you choose various export formats and options. These are generally single-key options so it's easy to set and execute. For instance, to export a document to a PDF, use C-c C-e l p or for HTML export, C-c C-e h h. - -There are lots of settings available for all of these export options; see the manual. It is, in fact, quite possible to use LaTeX-format equations in both LaTeX and HTML modes, to insert arbitrary preambles and settings for different modes, etc. - -#### 1.3 Add-on packages - -ELPA containts many addition exporters for org-mode as well. Check there for details. - -### 2 Beamer slides with org-mode - -#### 2.1 About Beamer - -[Beamer][14] is a LaTeX environment for making presentations. Its features include: - -* Automated generating of structural elements in the presentation (see, for example, [the Marburg theme][1]). This provides a visual reference for the audience of where they are in the presentation. - -* Strong help for structuring the presentation - -* Themes - -* Full LaTeX available - -#### 2.2 Benefits of Beamer in org-mode - -org-mode has a lot of benefits for working with Beamer. Among them: - -* org-mode's very easy and strong support for visualizing and changing the structure makes it very quick to reorganize your material. - -* Combined with org-babel, live source code (with syntax highlighting) and results can be embedded. - -* The syntax is often easier to work with. - -I have completely replaced my usage of LibreOffice/Powerpoint/GoogleDocs with org-mode and beamer. It is, in fact, rather frustrating when I have to use one of those tools, as they are nowhere near as strong as org-mode for visualizing a presentation structure. - -#### 2.3 Headline Levels - -org-mode's Beamer export will convert sections of your document (defined by headings) into slides. The question, of course, is: which sections? This is governed by the H [export setting][15] (org-export-headline-levels). - -There are many ways to go, which suit people. I like to have my presentation like this: - -``` -#+OPTIONS: H:2 -#+BEAMER_HEADER: \AtBeginSection{\frame{\sectionpage}} -``` - -This gives a standalone section slide for each major topic, to highlight major transitions, and then takes the level 2 (two asterisks) headings to set the slide. Many Beamer themes expect a third level of indirection, so you would set H:3 for them. - -#### 2.4 Themes and settings - -You can configure many Beamer and LaTeX settings in your document by inserting lines at the top of your org file. This document, for instance, defines: - -``` -#+TITLE: Documents and presentations with org-mode -#+AUTHOR: John Goerzen -#+BEAMER_HEADER: \institute{The Changelog} -#+PROPERTY: comments yes -#+PROPERTY: header-args :exports both :eval never-export -#+OPTIONS: H:2 -#+BEAMER_THEME: CambridgeUS -#+BEAMER_COLOR_THEME: default -``` - -#### 2.5 Advanced settings - -I like to change some colors, bullet formatting, and the like. I round out my document with: - -``` -# We can't just +BEAMER_INNER_THEME: default because that picks the theme default. -# Override per https://tex.stackexchange.com/questions/11168/change-bullet-style-formatting-in-beamer -#+BEAMER_INNER_THEME: default -#+LaTeX_CLASS_OPTIONS: [aspectratio=169] -#+BEAMER_HEADER: \definecolor{links}{HTML}{0000A0} -#+BEAMER_HEADER: \hypersetup{colorlinks=,linkcolor=,urlcolor=links} -#+BEAMER_HEADER: \setbeamertemplate{itemize items}[default] -#+BEAMER_HEADER: \setbeamertemplate{enumerate items}[default] -#+BEAMER_HEADER: \setbeamertemplate{items}[default] -#+BEAMER_HEADER: \setbeamercolor*{local structure}{fg=darkred} -#+BEAMER_HEADER: \setbeamercolor{section in toc}{fg=darkred} -#+BEAMER_HEADER: \setlength{\parskip}{\smallskipamount} -``` - -Here, aspectratio=169 sets a 16:9 aspect ratio, and the remaining are standard LaTeX/Beamer configuration bits. - -#### 2.6 Shrink (to fit) - -Sometimes you've got some really large code examples and you might prefer to just shrink the slide to fit. - -Just type C-c C-x p, set the BEAMER_opt property to shrink=15\. - -(Or a larger value of shrink). The previous slide uses this here. - -#### 2.7 Result - -Here's the end result: - - [][16] - -### 3 Interactive Slides - -#### 3.1 Interactive Emacs Slideshows - -With the [org-tree-slide package][17], you can display your slideshow from right within Emacs. Just run M-x org-tree-slide-mode. Then, use C-> and C-< to move between slides. - -You might find C-c C-x C-v (which is org-toggle-inline-images) helpful to cause the system to display embedded images. - -#### 3.2 HTML Slideshows - -There are a lot of ways to export org-mode presentations to HTML, with various levels of JavaScript integration. See the [non-beamer presentations section][18] of the org-mode wiki for details. - -### 4 Miscellaneous - -#### 4.1 Additional resources to accompany this post - -* [orgmode.org beamer tutorial][2] - -* [LaTeX wiki][3] - -* [Generating section title slides][4] - -* [Shrinking content to fit on slide][5] - -* A great resource: refcard-org-beamer See its [Github repo][6] Make sure to check out both the PDF and the .org file - -* A nice [Theme matrix][7] - -#### 4.2 Up next in my Emacs series… - -mu4e for email! - - --------------------------------------------------------------------------------- - -via: http://changelog.complete.org/archives/9900-emacs-5-documents-and-presentations-with-org-mode - -作者：[John Goerzen][a] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) -选题：[lujun9972](https://github.com/lujun9972) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:http://changelog.complete.org/archives/author/jgoerzen -[1]:https://hartwork.org/beamer-theme-matrix/all/beamer-albatross-Marburg-1.png -[2]:https://orgmode.org/worg/exporters/beamer/tutorial.html -[3]:https://en.wikibooks.org/wiki/LaTeX/Presentations -[4]:https://tex.stackexchange.com/questions/117658/automatically-generate-section-title-slides-in-beamer/117661 -[5]:https://tex.stackexchange.com/questions/78514/content-doesnt-fit-in-one-slide -[6]:https://github.com/fniessen/refcard-org-beamer -[7]:https://hartwork.org/beamer-theme-matrix/ -[8]:https://changelog.complete.org/archives/tag/emacs2018 -[9]:https://github.com/jgoerzen/public-snippets/blob/master/emacs/emacs-org-beamer/emacs-org-beamer.org -[10]:http://changelog.complete.org/archives/9900-emacs-5-documents-and-presentations-with-org-mode -[11]:https://github.com/jgoerzen/public-snippets/raw/master/emacs/emacs-org-beamer/emacs-org-beamer.pdf -[12]:https://github.com/jgoerzen/public-snippets/raw/master/emacs/emacs-org-beamer/emacs-org-beamer-document.pdf -[13]:https://orgmode.org/manual/Exporting.html#Exporting -[14]:https://en.wikipedia.org/wiki/Beamer_(LaTeX) -[15]:https://orgmode.org/manual/Export-settings.html#Export-settings -[16]:https://www.flickr.com/photos/jgoerzen/26366340577/in/dateposted/ -[17]:https://orgmode.org/worg/org-tutorials/non-beamer-presentations.html#org-tree-slide -[18]:https://orgmode.org/worg/org-tutorials/non-beamer-presentations.html diff --git a/sources/tech/20180409 How to create LaTeX documents with Emacs.md b/sources/tech/20180409 How to create LaTeX documents with Emacs.md deleted file mode 100644 index 7dc16bcf10..0000000000 --- a/sources/tech/20180409 How to create LaTeX documents with Emacs.md +++ /dev/null @@ -1,281 +0,0 @@ -How to create LaTeX documents with Emacs -====== - - -In his excellent article, [An introduction to creating documents in LaTeX][1], author [Aaron Cocker][2] introduces the [LaTeX typesetting system][3] and explains how to create a LaTeX document using [TeXstudio][4]. He also lists a few LaTeX editors that many users find helpful in creating LaTeX documents. - -This comment on the article by [Greg Pittman][5] caught my attention: "LaTeX seems like an awful lot of typing when you first start...". This is true. LaTeX involves a lot of typing and debugging, if you missed a special character like an exclamation mark, which can discourage many users, especially beginners. In this article, I will introduce you to [GNU Emacs][6] and describe how to use it to create LaTeX documents. - -### Creating your first document - -Launch Emacs by typing: -``` -emacs -q --no-splash helloworld.org - -``` - -The `-q` flag ensures that no Emacs initializations will load. The `--no-splash-screen` flag prevents splash screens to ensure that only one window is open, with the file `helloworld.org`. - -![Emacs startup screen][8] - -GNU Emacs with the helloworld.org file opened in a buffer window - -Let's add some LaTeX headers the Emacs way: Go to **Org** in the menu bar and select **Export/Publish**. - -![template_flow.png][10] - -Inserting a default template - -In the next window, Emacs offers options to either export or insert a template. Insert the template by entering **#** ([#] Insert template). This will move a cursor to a mini-buffer, where the prompt reads **Options category:**. At this time you may not know the category names; press Tab to see possible completions. Type "default" and press Enter. The following content will be inserted: -``` -#+TITLE: helloworld - -#+DATE: <2018-03-12 Mon> - -#+AUTHOR: - -#+EMAIL: makerpm@nubia - -#+OPTIONS: ':nil *:t -:t ::t <:t H:3 \n:nil ^:t arch:headline - -#+OPTIONS: author:t c:nil creator:comment d:(not "LOGBOOK") date:t - -#+OPTIONS: e:t email:nil f:t inline:t num:t p:nil pri:nil stat:t - -#+OPTIONS: tags:t tasks:t tex:t timestamp:t toc:t todo:t |:t - -#+CREATOR: Emacs 25.3.1 (Org mode 8.2.10) - -#+DESCRIPTION: - -#+EXCLUDE_TAGS: noexport - -#+KEYWORDS: - -#+LANGUAGE: en - -#+SELECT_TAGS: export - -``` - -Change the title, date, author, and email as you wish. Mine looks like this: -``` -#+TITLE: Hello World! My first LaTeX document - -#+DATE: \today - -#+AUTHOR: Sachin Patil - -#+EMAIL: psachin@redhat.com - -``` - -We don't want to create a Table of Contents yet, so change the value of `toc` from `t` to `nil` inline, as shown below: -``` -#+OPTIONS: tags:t tasks:t tex:t timestamp:t toc:nil todo:t |:t - -``` - -Let's add a section and paragraphs. A section starts with an asterisk (*). We'll copy the content of some paragraphs from Aaron's post (from the [Lipsum Lorem Ipsum generator][11]): -``` -* Introduction - - - - \paragraph{} - - Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras lorem - - nisi, tincidunt tempus sem nec, elementum feugiat ipsum. Nulla in - - diam libero. Nunc tristique ex a nibh egestas sollicitudin. - - - - \paragraph{} - - Mauris efficitur vitae ex id egestas. Vestibulum ligula felis, - - pulvinar a posuere id, luctus vitae leo. Sed ac imperdiet orci, non - - elementum leo. Nullam molestie congue placerat. Phasellus tempor et - - libero maximus commodo. - -``` - - -![helloworld_file.png][13] - -The helloworld.org file - -With the content in place, we'll export the content as a PDF. Select **Export/Publish** from the **Org** menu again, but this time, type **l** (export to LaTeX), followed by **o** (as PDF file and open). This not only opens PDF file for you to view, but also saves the file as `helloworld.pdf` in the same path as `helloworld.org`. - -![org_to_pdf.png][15] - -Exporting helloworld.org to helloworld.pdf - -![org_and_pdf_file.png][17] - -Opening the helloworld.pdf file - -You can also export org to PDF by pressing `Alt + x`, then typing "org-latex-export-to-pdf". Use Tab to auto-complete. - -Emacs also creates the `helloworld.tex` file to give you control over the content. - -![org_tex_pdf.png][19] - -Emacs with LaTeX, org, and PDF files open in three different windows - -You can compile the `.tex` file to `.pdf` using the command: -``` -pdflatex helloworld.tex - -``` - -You can also export the `.org` file to HTML or as a simple text file. What I like about .org files is they can be pushed to [GitHub][20], where they are rendered just like any other markdown formats. - -### Creating a LaTeX Beamer presentation - -Let's go a step further and create a LaTeX [Beamer][21] presentation using the same file with some modifications as shown below: -``` -#+TITLE: LaTeX Beamer presentation - -#+DATE: \today - -#+AUTHOR: Sachin Patil - -#+EMAIL: psachin@redhat.com - -#+OPTIONS: ':nil *:t -:t ::t <:t H:3 \n:nil ^:t arch:headline - -#+OPTIONS: author:t c:nil creator:comment d:(not "LOGBOOK") date:t - -#+OPTIONS: e:t email:nil f:t inline:t num:t p:nil pri:nil stat:t - -#+OPTIONS: tags:t tasks:t tex:t timestamp:t toc:nil todo:t |:t - -#+CREATOR: Emacs 25.3.1 (Org mode 8.2.10) - -#+DESCRIPTION: - -#+EXCLUDE_TAGS: noexport - -#+KEYWORDS: - -#+LANGUAGE: en - -#+SELECT_TAGS: export - -#+LATEX_CLASS: beamer - -#+BEAMER_THEME: Frankfurt - -#+BEAMER_INNER_THEME: rounded - - - - - -* Introduction - -*** Programming - - - Python - - - Ruby - - - -*** Paragraph one - - - - Lorem ipsum dolor sit amet, consectetur adipiscing - - elit. Cras lorem nisi, tincidunt tempus sem nec, elementum feugiat - - ipsum. Nulla in diam libero. Nunc tristique ex a nibh egestas - - sollicitudin. - - - -*** Paragraph two - - - - Mauris efficitur vitae ex id egestas. Vestibulum - - ligula felis, pulvinar a posuere id, luctus vitae leo. Sed ac - - imperdiet orci, non elementum leo. Nullam molestie congue - - placerat. Phasellus tempor et libero maximus commodo. - - - -* Thanks - -*** Links - - - Link one - - - Link two - -``` - -We have added three more lines to the header: -``` -#+LATEX_CLASS: beamer - -#+BEAMER_THEME: Frankfurt - -#+BEAMER_INNER_THEME: rounded - -``` - -To export to PDF, press `Alt + x` and type "org-beamer-export-to-pdf". - -![latex_beamer_presentation.png][23] - -The Latex Beamer presentation, created using Emacs and Org mode - -I hope you enjoyed creating this LaTeX and Beamer document using Emacs (note that it's faster to use keyboard shortcuts than a mouse). Emacs Org-mode offers much more than I can cover in this post; you can learn more at [orgmode.org][24]. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/4/how-create-latex-documents-emacs - -作者：[Sachin Patil][a] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) -选题：[lujun9972](https://github.com/lujun9972) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://opensource.com/users/psachin -[1]:https://opensource.com/article/17/6/introduction-latex -[2]:https://opensource.com/users/aaroncocker -[3]:https://www.latex-project.org -[4]:http://www.texstudio.org/ -[5]:https://opensource.com/users/greg-p -[6]:https://www.gnu.org/software/emacs/ -[7]:/file/392261 -[8]:https://opensource.com/sites/default/files/styles/panopoly_image_original/public/images/life-uploads/emacs_startup.png?itok=UnT4PgK5 (Emacs startup screen) -[9]:/file/392266 -[10]:https://opensource.com/sites/default/files/styles/panopoly_image_original/public/images/life-uploads/insert_template_flow.png?itok=V_c2KipO (template_flow.png) -[11]:https://www.lipsum.com/feed/html -[12]:/file/392271 -[13]:https://opensource.com/sites/default/files/styles/panopoly_image_original/public/images/life-uploads/helloworld_file.png?itok=o8IX0TsJ (helloworld_file.png) -[14]:/file/392276 -[15]:https://opensource.com/sites/default/files/styles/panopoly_image_original/public/images/life-uploads/org_to_pdf.png?itok=fNnC1Y-L (org_to_pdf.png) -[16]:/file/392281 -[17]:https://opensource.com/sites/default/files/styles/panopoly_image_original/public/images/life-uploads/org_and_pdf_file.png?itok=HEhtw-cu (org_and_pdf_file.png) -[18]:/file/392286 -[19]:https://opensource.com/sites/default/files/styles/panopoly_image_original/public/images/life-uploads/org_tex_pdf.png?itok=poZZV_tj (org_tex_pdf.png) -[20]:https://github.com -[21]:https://www.sharelatex.com/learn/Beamer -[22]:/file/392291 -[23]:https://opensource.com/sites/default/files/styles/panopoly_image_original/public/images/life-uploads/latex_beamer_presentation.png?itok=rsPSeIuM (latex_beamer_presentation.png) -[24]:https://orgmode.org/worg/org-tutorials/org-latex-export.html diff --git a/sources/tech/20180411 How To Setup Static File Server Instantly.md b/sources/tech/20180411 How To Setup Static File Server Instantly.md deleted file mode 100644 index b388b389fa..0000000000 --- a/sources/tech/20180411 How To Setup Static File Server Instantly.md +++ /dev/null @@ -1,171 +0,0 @@ -How To Setup Static File Server Instantly -====== - - -Ever wanted to share your files or project over network, but don’t know how to do? No worries! Here is a simple utility named **“serve”** to share your files instantly over network. This simple utility will instantly turn your system into a static file server, allowing you to serve your files over network. You can access the files from any devices regardless of their operating system. All you need is a web browser. This utility also can be used to serve static websites. It is formerly known as “list” and “micro-list”, but now the name has been changed to “serve”, which is much more suitable for the purpose of this utility. - -### Setup Static File Server Using Serve - -To install “serve”, you need to install NodeJS and NPM first. Refer the following link to install NodeJS and NPM in your Linux box. - -Once NodeJS and NPM installed, run the following command to install “serve”. -``` -$ npm install -g serve - -``` - -Done! Now is the time to serve the files or folders. - -The typical syntax to use “serve” is: -``` -$ serve [options] - -``` - -### Serve Specific files or folders - -For example, let us share the contents of the **Documents** directory. To do so, run: -``` -$ serve Documents/ - -``` - -Sample output would be: - -![][2] - -As you can see in the above screenshot, the contents of the given directory have been served over network via two URLs. - -To access the contents from the local system itself, all you have to do is open your web browser and navigate to ** - -``` - -For example, I am going to search for how to create tgz archive. -``` -$ how2 create archive tgz - -``` - -Oops! I get the following error. -``` -/home/sk/.nvm/versions/node/v9.11.1/lib/node_modules/how2/node_modules/devnull/transports/transport.js:59 -Transport.prototype.__proto__ = EventEmitter.prototype; - ^ - - TypeError: Cannot read property 'prototype' of undefined - at Object. (/home/sk/.nvm/versions/node/v9.11.1/lib/node_modules/how2/node_modules/devnull/transports/transport.js:59:46) - at Module._compile (internal/modules/cjs/loader.js:654:30) - at Object.Module._extensions..js (internal/modules/cjs/loader.js:665:10) - at Module.load (internal/modules/cjs/loader.js:566:32) - at tryModuleLoad (internal/modules/cjs/loader.js:506:12) - at Function.Module._load (internal/modules/cjs/loader.js:498:3) - at Module.require (internal/modules/cjs/loader.js:598:17) - at require (internal/modules/cjs/helpers.js:11:18) - at Object. (/home/sk/.nvm/versions/node/v9.11.1/lib/node_modules/how2/node_modules/devnull/transports/stream.js:8:17) - at Module._compile (internal/modules/cjs/loader.js:654:30) - -``` - -I may be a bug. I hope it gets fixed in the future versions. However, I find a workaround posted [**here**][3]. - -To fix this error temporarily, you need to edit the **transport.js** file using command: -``` -$ vi /home/sk/.nvm/versions/node/v9.11.1/lib/node_modules/how2/node_modules/devnull/transports/transport.js - -``` - -The actual path of this file will be displayed in your error output. Replace the above file path with your own. Then find the following line: -``` -var EventEmitter = process.EventEmitter; - -``` - -and replace it with following line: -``` -var EventEmitter = require('events'); - -``` - -Press ESC and type **:wq** to save and quit the file. - -Now search again the query. -``` -$ how2 create archive tgz - -``` - -Here is the sample output from my Ubuntu system. - -[![][4]][5] - -If the answer you’re looking for is not displayed in the above output, press **SPACE BAR** key to start the interactive search where you can go through all suggested questions and answers from the Stack Overflow site. - -[![][4]][6] - -Use UP/DOWN arrows to move between the results. Once you got the right answer/question, hit SPACE BAR or ENTER key to open it in the Terminal. - -[![][4]][7] - -To go back and exit, press **ESC**. - -**Search answers for specific language** - -If you don’t specify a language it **defaults to Bash** unix command line and give you immediately the most likely answer as above. You can also narrow the results to a specific language, for example perl, python, c, Java etc. - -For instance, to search for queries related to “Python” language only using **-l** flag as shown below. -``` -$ how2 -l python linked list - -``` - -[![][4]][8] - -To get a quick help, type: -``` -$ how2 -h - -``` - -### Conclusion - -The how2 utility is a basic command line program to quickly search for questions and answers from Stack Overflow without leaving your Terminal and it does this job pretty well. However, it is just CLI browser for Stack overflow. For some advanced features such as searching most voted questions, searching queries using multiple tags, colored interface, submitting a new question and viewing questions stats etc., **SoCLI** is good to go. - -And, that’s all for now. Hope this was useful. I will be soon here with another useful guide. Until then, stay tuned with OSTechNix! - -Cheers! - - - --------------------------------------------------------------------------------- - -via: https://www.ostechnix.com/how-to-browse-stack-overflow-from-terminal/ - -作者：[SK][a] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) -选题：[lujun9972](https://github.com/lujun9972) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://www.ostechnix.com/author/sk/ -[1]:https://www.ostechnix.com/search-browse-stack-overflow-website-commandline/ -[2]:https://www.ostechnix.com/google-search-navigator-enhance-keyboard-navigation-in-google-search/ -[3]:https://github.com/santinic/how2/issues/79 -[4]:data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 -[5]:http://www.ostechnix.com/wp-content/uploads/2018/04/stack-overflow-1.png -[6]:http://www.ostechnix.com/wp-content/uploads/2018/04/stack-overflow-2.png -[7]:http://www.ostechnix.com/wp-content/uploads/2018/04/stack-overflow-3.png -[8]:http://www.ostechnix.com/wp-content/uploads/2018/04/stack-overflow-4.png diff --git a/sources/tech/20180419 Migrating to Linux- Network and System Settings.md b/sources/tech/20180419 Migrating to Linux- Network and System Settings.md deleted file mode 100644 index f3930f1777..0000000000 --- a/sources/tech/20180419 Migrating to Linux- Network and System Settings.md +++ /dev/null @@ -1,116 +0,0 @@ -Migrating to Linux: Network and System Settings -====== - - -In this series, we provide an overview of fundamentals to help you successfully make the transition to Linux from another operating system. If you missed the earlier articles in the series, you can find them here: - -[Part 1 - An Introduction][1] - -[Part 2 - Disks, Files, and Filesystems][2] - -[Part 3 - Graphical Environments][3] - -[Part 4 - The Command Line][4] - -[Part 5 - Using sudo][5] - -[Part 6 - Installing Software][6] - -Linux gives you a lot of control over network and system settings. On your desktop, Linux lets you tweak just about anything on the system. Most of these settings are exposed in plain text files under the /etc directory. Here I describe some of the most common settings you’ll use on your desktop Linux system. - -A lot of settings can be found in the Settings program, and the available options will vary by Linux distribution. Usually, you can change the background, tweak sound volume, connect to printers, set up displays, and more. While I won't talk about all of the settings here, you can certainly explore what's in there. - -### Connect to the Internet - -Connecting to the Internet in Linux is often fairly straightforward. If you are wired through an Ethernet cable, Linux will usually get an IP address and connect automatically when the cable is plugged in or at startup if the cable is already connected. - -If you are using wireless, in most distributions there is a menu, either in the indicator panel or in settings (depending on your distribution), where you can select the SSID for your wireless network. If the network is password protected, it will usually prompt you for the password. Afterward, it connects, and the process is fairly smooth. - -You can adjust network settings in the graphical environment by going into settings. Sometimes this is called System Settings or just Settings. Often you can easily spot the settings program because its icon is a gear or a picture of tools (Figure 1). - - -![Network Settings][8] - -Figure 1: Gnome Desktop Network Settings Indicator Icon. - -[Used with permission][9] - -### Network Interface Names - -Under Linux, network devices have names. Historically, these are given names like eth0 and wlan0 -- or Ethernet and wireless, respectively. Newer Linux systems have been using different names that appear more esoteric, like enp4s0 and wlp5s0. If the name starts with en, it's a wired Ethernet interface. If it starts with wl, it's a wireless interface. The rest of the letters and numbers reflect how the device is connected to hardware. - -### Network Management from the Command Line - -If you want more control over your network settings, or if you are managing network connections without a graphical desktop, you can also manage the network from the command line. - -Note that the most common service used to manage networks in a graphical desktop is the Network Manager, and Network Manager will often override setting changes made on the command line. If you are using the Network Manager, it's best to change your settings in its interface so it doesn't undo the changes you make from the command line or someplace else. - -Changing settings in the graphical environment is very likely to be interacting with the Network Manager, and you can also change Network Manager settings from the command line using the tool called nmtui. The nmtui tool provides all the settings that you find in the graphical environment but gives it in a text-based semi-graphical interface that works on the command line (Figure 2). - - - -On the command line, there is an older tool called ifconfig to manage networks and a newer one called ip. On some distributions, ifconfig is considered to be deprecated and is not even installed by default. On other distributions, ifconfig is still in use. - -Here are some commands that will allow you to display and change network settings: - - - -### Process and System Information - -In Windows, you can go into the Task Manager to see a list of the all the programs and services that are running. You can also stop programs from running. And you can view system performance in some of the tabs displayed there. - -You can do similar things in Linux both from the command line and from graphical tools. In Linux, there are a few graphical tools available depending on your distribution. The most common ones are System Monitor or KSysGuard. In these tools, you can see system performance, see a list of processes, and even kill processes (Figure 3). - - - -In these tools, you can also view global network traffic on your system (Figure 4). - - -![System Monitor][11] - -Figure 4: Screenshot of Gnome System Monitor. - -[Used with permission][9] - -### Managing Process and System Usage - -There are also quite a few tools you can use from the command line. The command ps can be used to list processes on your system. By default, it will list processes running in your current terminal session. But you can list other processes by giving it various command line options. You can get more help on ps with the commands info ps, or man ps. - -Most folks though want to get a list of processes because they would like to stop the one that is using up too much memory or CPU time. In this case, there are two commands that make this task much easier. These are top and htop (Figure 5). - - - -The top and htop tools work very similarly to each other. These commands update their list every second or two and re-sort the list so that the task using the most CPU is at the top. You can also change the sorting to sort by other resources as well such as memory usage. - -In either of these programs (top and htop), you can type '?' to get help, and 'q' to quit. With top, you can press 'k' to kill a process and then type in the unique PID number for the process to kill it. - -With htop, you can highlight a task by pressing down arrow or up arrow to move the highlight bar, and then press F9 to kill the task followed by Enter to confirm. - -The information and tools provided in this series will help you get started with Linux. With a little time and patience, you'll feel right at home. - -Learn more about Linux through the free ["Introduction to Linux" ][12]course from The Linux Foundation and edX. - --------------------------------------------------------------------------------- - -via: https://www.linux.com/blog/learn/2018/4/migrating-linux-network-and-system-settings - -作者：[John Bonesio][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://www.linux.com/users/johnbonesio -[1]:https://www.linux.com/blog/learn/intro-to-linux/2017/10/migrating-linux-introduction -[2]:https://www.linux.com/blog/learn/intro-to-linux/2017/11/migrating-linux-disks-files-and-filesystems -[3]:https://www.linux.com/blog/learn/2017/12/migrating-linux-graphical-environments -[4]:https://www.linux.com/blog/learn/2018/1/migrating-linux-command-line -[5]:https://www.linux.com/blog/learn/2018/3/migrating-linux-using-sudo -[6]:https://www.linux.com/blog/learn/2018/3/migrating-linux-installing-software -[7]:https://www.linux.com/files/images/figure-1png-2 -[8]:https://www.linux.com/sites/lcom/files/styles/rendered_file/public/figure-1_2.png?itok=J-C6q-t5 (Network Settings) -[9]:https://www.linux.com/licenses/category/used-permission -[10]:https://www.linux.com/files/images/figure-4png-1 -[11]:https://www.linux.com/sites/lcom/files/styles/rendered_file/public/figure-4_1.png?itok=boI-L1mF (System Monitor) -[12]:https://training.linuxfoundation.org/linux-courses/system-administration-training/introduction-to-linux diff --git a/sources/tech/20180420 How To Remove Password From A PDF File in Linux.md b/sources/tech/20180420 How To Remove Password From A PDF File in Linux.md deleted file mode 100644 index 0e4318c858..0000000000 --- a/sources/tech/20180420 How To Remove Password From A PDF File in Linux.md +++ /dev/null @@ -1,220 +0,0 @@ -How To Remove Password From A PDF File in Linux -====== - - -Today I happen to share a password protected PDF file to one of my friend. I knew the password of that PDF file, but I didn’t want to disclose it. Instead, I just wanted to remove the password and send the file to him. I started to looking for some easy ways to remove the password protection from the pdf files on Internet. After a quick google search, I came up with four methods to remove password from a PDF file in Linux. The funny thing is I had already done it few years ago and I almost forgot it. If you’re wondering how to remove password from a PDF file in Linux, read on! It is not that difficult. - -### Remove Password From A PDF File in Linux - -**Method 1 – Using Qpdf** - -The **Qpdf** is a PDF transformation software which is used to encrypt and decrypt PDF files, convert PDF files to another equivalent pdf files. Qpdf is available in the default repositories of most Linux distributions, so you can install it using the default package manager. - -For example, Qpdf can be installed on Arch Linux and its variants using [**pacman**][1] as shown below. -``` -$ sudo pacman -S qpdf - -``` - -On Debian, Ubuntu, Linux Mint: -``` -$ sudo apt-get install qpdf - -``` - -Now let us remove the password from a pdf file using qpdf. - -I have a password-protected PDF file named **“secure.pdf”**. Whenever I open this file, it prompts me to enter the password to display its contents. - -![][3] - -I know the password of the above pdf file. However, I don’t want to share the password with anyone. So what I am going to do is to simply remove the password of the PDF file using Qpdf utility with following command. -``` -$ qpdf --password='123456' --decrypt secure.pdf output.pdf - -``` - -Quite easy, isn’t it? Yes, it is! Here, **123456** is the password of the **secure.pdf** file. Replace the password with your own. - -**Method 2 – Using Pdftk** - -**Pdftk** is yet another great software for manipulating pdf documents. Pdftk can do almost all sort of pdf operations, such as; - - * Encrypt and decrypt pdf files. - * Merge PDF documents. - * Collate PDF page Scans. - * Split PDF pages. - * Rotate PDF files or pages. - * Fill PDF forms with X/FDF data and/or flatten forms. - * Generate FDF data stencils from PDF forms. - * Apply a background watermark or a foreground stamp. - * Report PDF metrics, bookmarks and metadata. - * Add/update PDF bookmarks or metadata. - * Attach files to PDF pages or the PDF document. - * Unpack PDF attachments. - * Burst a PDF file into single pages. - * Compress and decompress page streams. - * Repair corrupted PDF file. - - - -Pddftk is available in AUR, so you can install it using any AUR helper programs on Arch Linux its derivatives. - -Using [**Pacaur**][4]: -``` -$ pacaur -S pdftk - -``` - -Using [**Packer**][5]: -``` -$ packer -S pdftk - -``` - -Using [**Trizen**][6]: -``` -$ trizen -S pdftk - -``` - -Using [**Yay**][7]: -``` -$ yay -S pdftk - -``` - -Using [**Yaourt**][8]: -``` -$ yaourt -S pdftk - -``` - -On Debian, Ubuntu, Linux Mint, run: -``` -$ sudo apt-get instal pdftk - -``` - -On CentOS, Fedora, Red Hat: - -First, Install EPEL repository: -``` -$ sudo yum install epel-release - -``` - -Or -``` -$ sudo dnf install epel-release - -``` - -Then install PDFtk application using command: -``` -$ sudo yum install pdftk - -``` - -Or -``` -$ sudo dnf install pdftk - -``` - -Once pdftk installed, you can remove the password from a pdf document using command: -``` -$ pdftk secure.pdf input_pw 123456 output output.pdf - -``` - -Replace ‘123456’ with your correct password. This command decrypts the “secure.pdf” file and create an equivalent non-password protected file named “output.pdf”. - -**Also read:** - -**Method 3 – Using Poppler** - -**Poppler** is a PDF rendering library based on the xpdf-3.0 code base. It contains the following set of command line utilities for manipulating PDF documents. - - * **pdfdetach** – lists or extracts embedded files. - * **pdffonts** – font analyzer. - * **pdfimages** – image extractor. - * **pdfinfo** – document information. - * **pdfseparate** – page extraction tool. - * **pdfsig** – verifies digital signatures. - * **pdftocairo** – PDF to PNG/JPEG/PDF/PS/EPS/SVG converter using Cairo. - * **pdftohtml** – PDF to HTML converter. - * **pdftoppm** – PDF to PPM/PNG/JPEG image converter. - * **pdftops** – PDF to PostScript (PS) converter. - * **pdftotext** – text extraction. - * **pdfunite** – document merging tool. - - - -For the purpose of this guide, we only use the “pdftops” utility. - -To install Poppler on Arch Linux based distributions, run: -``` -$ sudo pacman -S poppler - -``` - -On Debian, Ubuntu, Linux Mint: -``` -$ sudo apt-get install poppler-utils - -``` - -On RHEL, CentOS, Fedora: -``` -$ sudo yum install poppler-utils - -``` - -Once Poppler installed, run the following command to decrypt the password protected pdf file and create a new equivalent file named output.pdf. -``` -$ pdftops -upw 123456 secure.pdf output.pdf - -``` - -Again, replace ‘123456’ with your pdf password. - -As you might noticed in all above methods, we just converted the password protected pdf file named “secure.pdf” to another equivalent pdf file named “output.pdf”. Technically speaking, we really didn’t remove the password from the source file, instead we decrypted it and saved it as another equivalent pdf file without password protection. - -**Method 4 – Print to a file -** - -This is the easiest method in all of the above methods. You can use your existing PDF viewer such as Atril document viewer, Evince etc., and print the password protected pdf file to another file. - -Open the password protected file in your PDF viewer application. Go to **File - > Print**. And save the pdf file in any location of your choice. - -![][9] - -And, that’s all. Hope this was useful. Do you know/use any other methods to remove the password protection from PDF files? Let us know in the comment section below. - -More good stuffs to come. Stay tuned! - -Cheers! - - - --------------------------------------------------------------------------------- - -via: https://www.ostechnix.com/how-to-remove-password-from-a-pdf-file-in-linux/ - -作者：[SK][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://www.ostechnix.com/author/sk/ -[1]:https://www.ostechnix.com/getting-started-pacman/ -[2]:data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 -[3]:http://www.ostechnix.com/wp-content/uploads/2018/04/Remove-Password-From-A-PDF-File-1.png -[4]:https://www.ostechnix.com/install-pacaur-arch-linux/ -[5]:https://www.ostechnix.com/install-packer-arch-linux-2/ -[6]:https://www.ostechnix.com/trizen-lightweight-aur-package-manager-arch-based-systems/ -[7]:https://www.ostechnix.com/yay-found-yet-another-reliable-aur-helper/ -[8]:https://www.ostechnix.com/install-yaourt-arch-linux/ diff --git a/sources/tech/20180422 Command Line Tricks For Data Scientists - kade killary.md b/sources/tech/20180422 Command Line Tricks For Data Scientists - kade killary.md deleted file mode 100644 index aea3b6b035..0000000000 --- a/sources/tech/20180422 Command Line Tricks For Data Scientists - kade killary.md +++ /dev/null @@ -1,526 +0,0 @@ -Command Line Tricks For Data Scientists • kade killary -====== - - - -For many data scientists, data manipulation begins and ends with Pandas or the Tidyverse. In theory, there is nothing wrong with this notion. It is, after all, why these tools exist in the first place. Yet, these options can often be overkill for simple tasks like delimiter conversion. - -Aspiring to master the command line should be on every developer’s list, especially data scientists. Learning the ins and outs of your shell will undeniably make you more productive. Beyond that, the command line serves as a great history lesson in computing. For instance, awk - a data-driven scripting language. Awk first appeared in 1977 with the help of [Brian Kernighan][1], the K in the legendary [K&R book][2]. Today, some near 50 years later, awk remains relevant with [new books][3] still appearing every year! Thus, it’s safe to assume that an investment in command line wizardry won’t depreciate any time soon. - -### What We’ll Cover - - * ICONV - * HEAD - * TR - * WC - * SPLIT - * SORT & UNIQ - * CUT - * PASTE - * JOIN - * GREP - * SED - * AWK - - - -### ICONV - -File encodings can be tricky. For the most part files these days are all UTF-8 encoded. To understand some of the magic behind UTF-8, check out this [excellent video][4]. Nonetheless, there are times where we receive a file that isn’t in this format. This can lead to some wonky attempts at swapping the encoding schema. Here, `iconv` is a life saver. Iconv is a simple program that will take text in one encoding and output the text in another. -``` -# Converting -f (from) latin1 (ISO-8859-1) -# -t (to) standard UTF_8 - -iconv -f ISO-8859-1 -t UTF-8 < input.txt > output.txt - -``` - - * Useful options: - - * `iconv -l` list all known encodings - * `iconv -c` silently discard characters that cannot be converted - - - -### HEAD - -If you are a frequent Pandas user then `head` will be familiar. Often when dealing with new data the first thing we want to do is get a sense of what exists. This leads to firing up Pandas, reading in the data and then calling `df.head()` \- strenuous, to say the least. Head, without any flags, will print out the first 10 lines of a file. The true power of `head` lies in testing out cleaning operations. For instance, if we wanted to change the delimiter of a file from commas to pipes. One quick test would be: `head mydata.csv | sed 's/,/|/g'`. -``` -# Prints out first 10 lines - -head filename.csv - -# Print first 3 lines - -head -n 3 filename.csv - -``` - - * Useful options: - - * `head -n` print a specific number of lines - * `head -c` print a specific number of bytes - - - -### TR - -Tr is analogous to translate. This powerful utility is a workhorse for basic file cleaning. An ideal use case is for swapping out the delimiters within a file. -``` -# Converting a tab delimited file into commas - -cat tab_delimited.txt | tr "\t" "," comma_delimited.csv - -``` - -Another feature of `tr` is all the built in `[:class:]` variables at your disposal. These include: -``` -[:alnum:] all letters and digits -[:alpha:] all letters -[:blank:] all horizontal whitespace -[:cntrl:] all control characters -[:digit:] all digits -[:graph:] all printable characters, not including space -[:lower:] all lower case letters -[:print:] all printable characters, including space -[:punct:] all punctuation characters -[:space:] all horizontal or vertical whitespace -[:upper:] all upper case letters -[:xdigit:] all hexadecimal digits - -``` - -You can chain a variety of these together to compose powerful programs. The following is a basic word count program you could use to check your READMEs for overuse. -``` -cat README.md | tr "[:punct:][:space:]" "\n" | tr "[:upper:]" "[:lower:]" | grep . | sort | uniq -c | sort -nr - -``` - -Another example using basic regex: -``` -# Converting all upper case letters to lower case - -cat filename.csv | tr '[A-Z]' '[a-z]' - -``` - - * Useful options: - - * `tr -d` delete characters - * `tr -s` squeeze characters - * `\b` backspace - * `\f` form feed - * `\v` vertical tab - * `\NNN` character with octal value NNN - - - -### WC - -Word count. Its value is primarily derived from the `-l` flag, which will give you the line count. -``` -# Will return number of lines in CSV - -wc -l gigantic_comma.csv - -``` - -This tool comes in handy to confirm the output of various commands. So, if we were to convert the delimiters within a file and then run `wc -l` we would expect the total lines to be the same. If not, then we know something went wrong. - - * Useful options: - - * `wc -c` print the byte counts - * `wc -m` print the character counts - * `wc -L` print length of longest line - * `wc -w` print word counts - - - -### SPLIT - -File sizes can range dramatically. And depending on the job, it could be beneficial to split up the file - thus `split`. The basic syntax for split is: -``` -# We will split our CSV into new_filename every 500 lines - -split -l 500 filename.csv new_filename_ - -# filename.csv -# ls output -# new_filename_aaa -# new_filename_aab -# new_filename_aac - -``` - -Two quirks are the naming convention and lack of file extensions. The suffix convention can be numeric via the `-d` flag. To add file extensions, you’ll need to run the following `find` command. It will change the names of ALL files within the current directory by appending `.csv`, so be careful. -``` -find . -type f -exec mv '{}' '{}'.csv \; - -# ls output -# filename.csv.csv -# new_filename_aaa.csv -# new_filename_aab.csv -# new_filename_aac.csv - -``` - - * Useful options: - - * `split -b` split by certain byte size - * `split -a` generate suffixes of length N - * `split -x` split using hex suffixes - - - -### SORT & UNIQ - -The preceding commands are obvious: they do what they say they do. These two provide the most punch in tandem (i.e. unique word counts). This is due to `uniq`, which only operates on duplicate adjacent lines. Thus, the reason to `sort` before piping the output through. One interesting note is that `sort -u` will achieve the same results as the typical `sort file.txt | uniq` pattern. - -Sort does have a sneakily useful ability for data scientists: the ability to sort an entire CSV based on a particular column. -``` -# Sorting a CSV file by the second column alphabetically - -sort -t"," -k2,2 filename.csv - -# Numerically - -sort -t"," -k2n,2 filename.csv - -# Reverse order - -sort -t"," -k2nr,2 filename.csv - -``` - -The `-t` option here is to specify the comma as our delimiter. More often than not spaces or tabs are assumed. Furthermore, the `-k` flag is for specifying our key. The syntax for this is `-km,n`, with `m` being the starting field and `n` being the last. - - * Useful options: - - * `sort -f` ignore case - * `sort -r` reverse sort order - * `sort -R` scramble order - * `uniq -c` count number of occurrences - * `uniq -d` only print duplicate lines - - - -### CUT - -Cut is for removing columns. To illustrate, if we only wanted the first and third columns. -``` -cut -d, -f 1,3 filename.csv - -``` - -To select every column other than the first. -``` -cut -d, -f 2- filename.csv - -``` - -In combination with other commands, `cut` serves as a filter. -``` -# Print first 10 lines of column 1 and 3, where "some_string_value" is present - -head filename.csv | grep "some_string_value" | cut -d, -f 1,3 - -``` - -Finding out the number of unique values within the second column. -``` -cat filename.csv | cut -d, -f 2 | sort | uniq | wc -l - -# Count occurences of unique values, limiting to first 10 results - -cat filename.csv | cut -d, -f 2 | sort | uniq -c | head - -``` - -### PASTE - -Paste is a niche command with an interesting function. If you have two files that you need merged, and they are already sorted, `paste` has you covered. -``` -# names.txt -adam -john -zach - -# jobs.txt -lawyer -youtuber -developer - -# Join the two into a CSV - -paste -d ',' names.txt jobs.txt > person_data.txt - -# Output -adam,lawyer -john,youtuber -zach,developer - -``` - -For a more SQL_-esque variant, see below. - -### JOIN - -Join is a simplistic, quasi-tangential, SQL. The largest differences being that `join` will return all columns and matches can only be on one field. By default, `join` will try and use the first column as the match key. For a different result, the following syntax is necessary: -``` -# Join the first file (-1) by the second column -# and the second file (-2) by the first - -join -t"," -1 2 -2 1 first_file.txt second_file.txt - -``` - -The standard join is an inner join. However, an outer join is also viable through the `-a` flag. Another noteworthy quirk is the `-e` flag, which can be used to substitute a value if a missing field is found. -``` -# Outer join, replace blanks with NULL in columns 1 and 2 -# -o which fields to substitute - 0 is key, 1.1 is first column, etc... - -join -t"," -1 2 -a 1 -a2 -e ' NULL' -o '0,1.1,2.2' first_file.txt second_file.txt - -``` - -Not the most user-friendly command, but desperate times, desperate measures. - - * Useful options: - - * `join -a` print unpairable lines - * `join -e` replace missing input fields - * `join -j` equivalent to `-1 FIELD -2 FIELD` - - - -### GREP - -Global search for a regular expression and print, or `grep`; likely, the most well known command, and with good reason. Grep has a lot of power, especially for finding your way around large codebases. Within the realm of data science, it acts as a refining mechanism for other commands. Although its standard usage is valuable as well. -``` -# Recursively search and list all files in directory containing 'word' - -grep -lr 'word' . - -# List number of files containing word - -grep -lr 'word' . | wc -l - -``` - -Count total number of lines containing word / pattern. -``` -grep -c 'some_value' filename.csv - -# Same thing, but in all files in current directory by file name - -grep -c 'some_value' * - -``` - -Grep for multiple values using the or operator - `\|`. -``` -grep "first_value\|second_value" filename.csv - -``` - - * Useful options - - * `alias grep="grep --color=auto"` make grep colorful - * `grep -E` use extended regexps - * `grep -w` only match whole words - * `grep -l` print name of files with match - * `grep -v` inverted matching - - - -### THE BIG GUNS - -Sed and Awk are the two most powerful commands in this article. For brevity, I’m not going to go into exhausting detail about either. Instead, I will cover a variety of commands that prove their impressive might. If you want to know more, [there is a book][5] just for that. - -### SED - -At its core `sed` is a stream editor. It excels at substitutions, but can also be leveraged for all out refactoring. - -The most basic `sed` command consists of `s/old/new/g`. This translates to search for old value, replace with new globally. Without the `/g` our command would terminate after the first occurrence. - -To get a quick taste of the power lets dive into an example. In this scenario you’ve been given the following file: -``` -balance,name -$1,000,john -$2,000,jack - -``` - -The first thing we may want to do is remove the dollar signs. The `-i` flag indicates in-place. The `''` is to indicate a zero-length file extension, thus overwriting our initial file. Ideally, you would test each of these individually and then output to a new file. -``` -sed -i '' 's/\$//g' data.txt - -# balance,name -# 1,000,john -# 2,000,jack - -``` - -Next up, the commas in our `balance` column values. -``` -sed -i '' 's/\([0-9]\),\([0-9]\)/\1\2/g' data.txt - -# balance,name -# 1000,john -# 2000,jack - -``` - -Lastly, Jack up and decided to quit one day. So, au revoir, mon ami. -``` -sed -i '' '/jack/d' data.txt - -# balance,name -# 1000,john - -``` - -As you can see, `sed` packs quite a punch, but the fun doesn’t stop there. - -### AWK - -The best for last. Awk is much more than a simple command: it is a full-blown language. Of everything covered in this article, `awk` is by far the coolest. If you find yourself impressed there are loads of great resources - see [here][6], [here][7] and [here][8]. - -Common use cases for `awk` include: - - * Text processing - * Formatted text reports - * Performing arithmetic operations - * Performing string operations - - - -Awk can parallel `grep` in its most nascent form. -``` -awk '/word/' filename.csv - -``` - -Or with a little more magic the combination of `grep` and `cut`. Here, `awk` prints the third and fourth column, tab separated, for all lines with our word. `-F,` merely changes our delimiter to a comma. -``` -awk -F, '/word/ { print $3 "\t" $4 }' filename.csv - -``` - -Awk comes with a lot of nifty variables built-in. For instance, `NF` \- number of fields - and `NR` \- number of records. To get the fifty-third record in a file: -``` -awk -F, 'NR == 53' filename.csv - -``` - -An added wrinkle is the ability to filter based off of one or more values. The first example, below, will print the line number and columns for records where the first column equals string. -``` -awk -F, ' $1 == "string" { print NR, $0 } ' filename.csv - -# Filter based off of numerical value in second column - -awk -F, ' $2 == 1000 { print NR, $0 } ' filename.csv - -``` - -Multiple numerical expressions: -``` -# Print line number and columns where column three greater -# than 2005 and column five less than one thousand - -awk -F, ' $3 >= 2005 && $5 <= 1000 { print NR, $0 } ' filename.csv - -``` - -Sum the third column: -``` -awk -F, '{ x+=$3 } END { print x }' filename.csv - -``` - -The sum of the third column, for values where the first column equals “something”. -``` -awk -F, '$1 == "something" { x+=$3 } END { print x }' filename.csv - -``` - -Get the dimensions of a file: -``` -awk -F, 'END { print NF, NR }' filename.csv - -# Prettier version - -awk -F, 'BEGIN { print "COLUMNS", "ROWS" }; END { print NF, NR }' filename.csv - -``` - -Print lines appearing twice: -``` -awk -F, '++seen[$0] == 2' filename.csv - -``` - -Remove duplicate lines: -``` -# Consecutive lines -awk 'a !~ $0; {a=$0}'] - -# Nonconsecutive lines -awk '! a[$0]++' filename.csv - -# More efficient -awk '!($0 in a) {a[$0];print} - -``` - -Substitute multiple values using built-in function `gsub()`. -``` -awk '{gsub(/scarlet|ruby|puce/, "red"); print}' - -``` - -This `awk` command will combine multiple CSV files, ignoring the header and then append it at the end. -``` -awk 'FNR==1 && NR!=1{next;}{print}' *.csv > final_file.csv - -``` - -Need to downsize a massive file? Welp, `awk` can handle that with help from `sed`. Specifically, this command breaks one big file into multiple smaller ones based on a line count. This one-liner will also add an extension. -``` -sed '1d;$d' filename.csv | awk 'NR%NUMBER_OF_LINES==1{x="filename-"++i".csv";}{print > x}' - -# Example: splitting big_data.csv into data_(n).csv every 100,000 lines - -sed '1d;$d' big_data.csv | awk 'NR%100000==1{x="data_"++i".csv";}{print > x}' - -``` - -### CLOSING - -The command line boasts endless power. The commands covered in this article are enough to elevate you from zero to hero in no time. Beyond those covered, there are many utilities to consider for daily data operations. [Csvkit][9], [xsv][10] and [q][11] are three of note. If you’re looking to take an even deeper dive into command line data science, then look no further than [this book][12]. It’s also available online [for free][13]! - --------------------------------------------------------------------------------- - -via: http://kadekillary.work/post/cli-4-ds/ - -作者：[Kade Killary][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:http://kadekillary.work/authors/kadekillary -[1]:https://en.wikipedia.org/wiki/Brian_Kernighan -[2]:https://en.wikipedia.org/wiki/The_C_Programming_Language -[3]:https://www.amazon.com/Learning-AWK-Programming-cutting-edge-text-processing-ebook/dp/B07BT98HDS -[4]:https://www.youtube.com/watch?v=MijmeoH9LT4 -[5]:https://www.amazon.com/sed-awk-Dale-Dougherty/dp/1565922255/ref=sr_1_1?ie=UTF8&qid=1524381457&sr=8-1&keywords=sed+and+awk -[6]:https://www.amazon.com/AWK-Programming-Language-Alfred-Aho/dp/020107981X/ref=sr_1_1?ie=UTF8&qid=1524388936&sr=8-1&keywords=awk -[7]:http://www.grymoire.com/Unix/Awk.html -[8]:https://www.tutorialspoint.com/awk/index.htm -[9]:http://csvkit.readthedocs.io/en/1.0.3/ -[10]:https://github.com/BurntSushi/xsv -[11]:https://github.com/harelba/q -[12]:https://www.amazon.com/Data-Science-Command-Line-Time-Tested/dp/1491947853/ref=sr_1_1?ie=UTF8&qid=1524390894&sr=8-1&keywords=data+science+at+the+command+line -[13]:https://www.datascienceatthecommandline.com/ diff --git a/sources/tech/20180425 Things to do After Installing Ubuntu 18.04.md b/sources/tech/20180425 Things to do After Installing Ubuntu 18.04.md deleted file mode 100644 index 4e69d04837..0000000000 --- a/sources/tech/20180425 Things to do After Installing Ubuntu 18.04.md +++ /dev/null @@ -1,294 +0,0 @@ -Things to do After Installing Ubuntu 18.04 -====== -**Brief: This list of things to do after installing Ubuntu 18.04 helps you get started with Bionic Beaver for a smoother desktop experience.** - -[Ubuntu][1] 18.04 Bionic Beaver releases today. You are perhaps already aware of the [new features in Ubuntu 18.04 LTS][2] release. If not, here’s the video review of Ubuntu 18.04 LTS: - -[Subscribe to YouTube Channel for more Ubuntu Videos][3] - -If you opted to install Ubuntu 18.04, I have listed out a few recommended steps that you can follow to get started with it. - -### Things to do after installing Ubuntu 18.04 Bionic Beaver - -![Things to do after installing Ubuntu 18.04][4] - -I should mention that the list of things to do after installing Ubuntu 18.04 depends a lot on you and your interests and needs. If you are a programmer, you’ll focus on installing programming tools. If you are a graphic designer, you’ll focus on installing graphics tools. - -Still, there are a few things that should be applicable to most Ubuntu users. This list is composed of those things plus a few of my of my favorites. - -Also, this list is for the default [GNOME desktop][5]. If you are using some other flavor like [Kubuntu][6], Lubuntu etc then the GNOME-specific stuff won’t be applicable to your system. - -You don’t have to follow each and every point on the list blindly. You should see if the recommended action suits your requirements or not. - -With that said, let’s get started with this list of things to do after installing Ubuntu 18.04. - -#### 1\. Update the system - -This is the first thing you should do after installing Ubuntu. Update the system without fail. It may sound strange because you just installed a fresh OS but still, you must check for the updates. - -In my experience, if you don’t update the system right after installing Ubuntu, you might face issues while trying to install a new program. - -To update Ubuntu 18.04, press Super Key (Windows Key) to launch the Activity Overview and look for Software Updater. Run it to check for updates. - -![Software Updater in Ubuntu 17.10][7] - -**Alternatively** , you can use these famous commands in the terminal ( Use Ctrl+Alt+T): -``` -sudo apt update && sudo apt upgrade - -``` - -#### 2\. Enable additional repositories for more software - -[Ubuntu has several repositories][8] from where it provides software for your system. These repositories are: - - * Main – Free and open-source software supported by Ubuntu team - * Universe – Free and open-source software maintained by the community - * Restricted – Proprietary drivers for devices. - * Multiverse – Software restricted by copyright or legal issues. - * Canonical Partners – Software packaged by Ubuntu for their partners - - - -Enabling all these repositories will give you access to more software and proprietary drivers. - -Go to Activity Overview by pressing Super Key (Windows key), and search for Software & Updates: - -![Software and Updates in Ubuntu 17.10][9] - -Under the Ubuntu Software tab, make sure you have checked all of the Main, Universe, Restricted and Multiverse repository checked. - -![Setting repositories in Ubuntu 18.04][10] - -Now move to the **Other Software** tab, check the option of **Canonical Partners**. - -![Enable Canonical Partners repository in Ubuntu 17.10][11] - -You’ll have to enter your password in order to update the software sources. Once it completes, you’ll find more applications to install in the Software Center. - -#### 3\. Install media codecs - -In order to play media files like MP#, MPEG4, AVI etc, you’ll need to install media codecs. Ubuntu has them in their repository but doesn’t install it by default because of copyright issues in various countries. - -As an individual, you can install these media codecs easily using the Ubuntu Restricted Extra package. Click on the link below to install it from the Software Center. - -[Install Ubuntu Restricted Extras][12] - -Or alternatively, use the command below to install it: -``` -sudo apt install ubuntu-restricted-extras - -``` - -#### 4\. Install software from the Software Center - -Now that you have setup the repositories and installed the codecs, it is time to get software. If you are absolutely new to Ubuntu, please follow this [guide to installing software in Ubuntu][13]. - -There are several ways to install software. The most convenient way is to use the Software Center that has thousands of software available in various categories. You can install them in a few clicks from the software center. - -![Software Center in Ubuntu 17.10 ][14] - -It depends on you what kind of software you would like to install. I’ll suggest some of my favorites here. - - * **VLC** – media player for videos - * **GIMP** – Photoshop alternative for Linux - * **Pinta** – Paint alternative in Linux - * **Calibre** – eBook management tool - * **Chromium** – Open Source web browser - * **Kazam** – Screen recorder tool - * [**Gdebi**][15] – Lightweight package installer for .deb packages - * **Spotify** – For streaming music - * **Skype** – For video messaging - * **Kdenlive** – [Video editor for Linux][16] - * **Atom** – [Code editor][17] for programming - - - -You may also refer to this list of [must-have Linux applications][18] for more software recommendations. - -#### 5\. Install software from the Web - -Though Ubuntu has thousands of applications in the software center, you may not find some of your favorite applications despite the fact that they support Linux. - -Many software vendors provide ready to install .deb packages. You can download these .deb files from their website and install it by double-clicking on it. - -[Google Chrome][19] is one such software that you can download from the web and install it. - -#### 6\. Opt out of data collection in Ubuntu 18.04 (optional) - -Ubuntu 18.04 collects some harmless statistics about your system hardware and your system installation preference. It also collects crash reports. - -You’ll be given the option to not send this data to Ubuntu servers when you log in to Ubuntu 18.04 for the first time. - -![Opt out of data collection in Ubuntu 18.04][20] - -If you miss it that time, you can disable it by going to System Settings -> Privacy and then set the Problem Reporting to Manual. - -![Privacy settings in Ubuntu 18.04][21] - -#### 7\. Customize the GNOME desktop (Dock, themes, extensions and more) - -The GNOME desktop looks good in Ubuntu 18.04 but doesn’t mean you cannot change it. - -You can do a few visual changes from the System Settings. You can change the wallpaper of the desktop and the lock screen, you can change the position of the dock (launcher on the left side), change power settings, Bluetooth etc. In short, you can find many settings that you can change as per your need. - -![Ubuntu 17.10 System Settings][22] - -Changing themes and icons are the major way to change the looks of your system. I advise going through the list of [best GNOME themes][23] and [icons for Ubuntu][24]. Once you have found the theme and icon of your choice, you can use them with GNOME Tweaks tool. - -You can install GNOME Tweaks via the Software Center or you can use the command below to install it: -``` -sudo apt install gnome-tweak-tool - -``` - -Once it is installed, you can easily [install new themes and icons][25]. - -![Change theme is one of the must to do things after installing Ubuntu 17.10][26] - -You should also have a look at [use GNOME extensions][27] to further enhance the looks and capabilities of your system. I made this video about using GNOME extensions in 17.10 and you can follow the same for Ubuntu 18.04. - -If you are wondering which extension to use, do take a look at this list of [best GNOME extensions][28]. - -I also recommend reading this article on [GNOME customization in Ubuntu][29] so that you can know the GNOME desktop in detail. - -#### 8\. Prolong your battery and prevent overheating - -Let’s move on to [prevent overheating in Linux laptops][30]. TLP is a wonderful tool that controls CPU temperature and extends your laptops’ battery life in the long run. - -Make sure that you haven’t installed any other power saving application such as [Laptop Mode Tools][31]. You can install it using the command below in a terminal: -``` -sudo apt install tlp tlp-rdw - -``` - -Once installed, run the command below to start it: -``` -sudo tlp start - -``` - -#### 9\. Save your eyes with Nightlight - -Nightlight is my favorite feature in GNOME desktop. Keeping [your eyes safe at night][32] from the computer screen is very important. Reducing blue light helps reducing eye strain at night. - -![flux effect][33] - -GNOME provides a built-in Night Light option, which you can activate in the System Settings. - -Just go to System Settings-> Devices-> Displays and turn on the Night Light option. - -![Enabling night light is a must to do in Ubuntu 17.10][34] - -#### 9\. Disable automatic suspend for laptops - -Ubuntu 18.04 comes with a new automatic suspend feature for laptops. If the system is running on battery and is inactive for 20 minutes, it will go in suspend mode. - -I understand that the intention is to save battery life but it is an inconvenience as well. You can’t keep the power plugged in all the time because it’s not good for the battery life. And you may need the system to be running even when you are not using it. - -Thankfully, you can change this behavior. Go to System Settings -> Power. Under Suspend & Power Button section, either turn off the Automatic Suspend option or extend its time period. - -![Disable automatic suspend in Ubuntu 18.04][35] - -You can also change the screen dimming behavior in here. - -#### 10\. System cleaning - -I have written in detail about [how to clean up your Ubuntu system][36]. I recommend reading that article to know various ways to keep your system free of junk. - -Normally, you can use this little command to free up space from your system: -``` -sudo apt autoremove - -``` - -It’s a good idea to run this command every once a while. If you don’t like the command line, you can use a GUI tool like [Stacer][37] or [Bleach Bit][38]. - -#### 11\. Going back to Unity or Vanilla GNOME (not recommended) - -If you have been using Unity or GNOME in the past, you may not like the new customized GNOME desktop in Ubuntu 18.04. Ubuntu has customized GNOME so that it resembles Unity but at the end of the day, it is neither completely Unity nor completely GNOME. - -So if you are a hardcore Unity or GNOMEfan, you may want to use your favorite desktop in its ‘real’ form. I wouldn’t recommend but if you insist here are some tutorials for you: - -#### 12\. Can’t log in to Ubuntu 18.04 after incorrect password? Here’s a workaround - -I noticed a [little bug in Ubuntu 18.04][39] while trying to change the desktop session to Ubuntu Community theme. It seems if you try to change the sessions at the login screen, it rejects your password first and at the second attempt, the login gets stuck. You can wait for 5-10 minutes to get it back or force power it off. - -The workaround here is that after it displays the incorrect password message, click Cancel, then click your name, then enter your password again. - -#### 13\. Experience the Community theme (optional) - -Ubuntu 18.04 was supposed to have a dashing new theme developed by the community. The theme could not be completed so it could not become the default look of Bionic Beaver release. I am guessing that it will be the default theme in Ubuntu 18.10. - -![Ubuntu 18.04 Communitheme][40] - -You can try out the aesthetic theme even today. [Installing Ubuntu Community Theme][41] is very easy. Just look for it in the software center, install it, restart your system and then at the login choose the Communitheme session. - -#### 14\. Get Windows 10 in Virtual Box (if you need it) - -In a situation where you must use Windows for some reasons, you can [install Windows in virtual box inside Linux][42]. It will run as a regular Ubuntu application. - -It’s not the best way but it still gives you an option. You can also [use WINE to run Windows software on Linux][43]. In both cases, I suggest trying the alternative native Linux application first before jumping to virtual machine or WINE. - -#### What do you do after installing Ubuntu? - -Those were my suggestions for getting started with Ubuntu. There are many more tutorials that you can find under [Ubuntu 18.04][44] tag. You may go through them as well to see if there is something useful for you. - -Enough from myside. Your turn now. What are the items on your list of **things to do after installing Ubuntu 18.04**? The comment section is all yours. - --------------------------------------------------------------------------------- - -via: https://itsfoss.com/things-to-do-after-installing-ubuntu-18-04/ - -作者：[Abhishek Prakash][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:http://itsfoss.com/author/abhishek/ -[1]:https://www.ubuntu.com/ -[2]:https://itsfoss.com/ubuntu-18-04-release-features/ -[3]:https://www.youtube.com/c/itsfoss?sub_confirmation=1 -[4]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/04/things-to-after-installing-ubuntu-18-04-featured-800x450.jpeg -[5]:https://www.gnome.org/ -[6]:https://kubuntu.org/ -[7]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2017/10/software-update-ubuntu-17-10.jpg -[8]:https://help.ubuntu.com/community/Repositories/Ubuntu -[9]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2017/10/software-updates-ubuntu-17-10.jpg -[10]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/04/repositories-ubuntu-18.png -[11]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2017/10/software-repository-ubuntu-17-10.jpeg -[12]:apt://ubuntu-restricted-extras -[13]:https://itsfoss.com/remove-install-software-ubuntu/ -[14]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2017/10/Ubuntu-software-center-17-10-800x551.jpeg -[15]:https://itsfoss.com/gdebi-default-ubuntu-software-center/ -[16]:https://itsfoss.com/best-video-editing-software-linux/ -[17]:https://itsfoss.com/best-modern-open-source-code-editors-for-linux/ -[18]:https://itsfoss.com/essential-linux-applications/ -[19]:https://www.google.com/chrome/ -[20]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/04/opt-out-of-data-collection-ubuntu-18-800x492.jpeg -[21]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/04/privacy-ubuntu-18-04-800x417.png -[22]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2017/10/System-Settings-Ubuntu-17-10-800x573.jpeg -[23]:https://itsfoss.com/best-gtk-themes/ -[24]:https://itsfoss.com/best-icon-themes-ubuntu-16-04/ -[25]:https://itsfoss.com/install-themes-ubuntu/ -[26]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2017/10/GNOME-Tweak-Tool-Ubuntu-17-10.jpeg -[27]:https://itsfoss.com/gnome-shell-extensions/ -[28]:https://itsfoss.com/best-gnome-extensions/ -[29]:https://itsfoss.com/gnome-tricks-ubuntu/ -[30]:https://itsfoss.com/reduce-overheating-laptops-linux/ -[31]:https://wiki.archlinux.org/index.php/Laptop_Mode_Tools -[32]:https://itsfoss.com/night-shift-flux-ubuntu-linux/ -[33]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2016/03/flux-eyes-strain.jpg -[34]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2017/10/Enable-Night-Light-Feature-Ubuntu-17-10-800x396.jpeg -[35]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/04/disable-automatic-suspend-ubuntu-18-800x586.jpeg -[36]:https://itsfoss.com/free-up-space-ubuntu-linux/ -[37]:https://itsfoss.com/optimize-ubuntu-stacer/ -[38]:https://itsfoss.com/bleachbit-2-release/ -[39]:https://gitlab.gnome.org/GNOME/gnome-shell/issues/227 -[40]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/04/ubunt-18-theme.jpeg -[41]:https://itsfoss.com/ubuntu-community-theme/ -[42]:https://itsfoss.com/install-windows-10-virtualbox-linux/ -[43]:https://itsfoss.com/use-windows-applications-linux/ -[44]:https://itsfoss.com/tag/ubuntu-18-04/ diff --git a/sources/tech/20180428 A Beginners Guide To Flatpak.md b/sources/tech/20180428 A Beginners Guide To Flatpak.md deleted file mode 100644 index db1dfa8181..0000000000 --- a/sources/tech/20180428 A Beginners Guide To Flatpak.md +++ /dev/null @@ -1,311 +0,0 @@ -A Beginners Guide To Flatpak -====== - - - -A while, we have written about [**Ubuntu’s Snaps**][1]. Snaps are introduced by Canonical for Ubuntu operating system, and later it was adopted by other Linux distributions such as Arch, Gentoo, and Fedora etc. A snap is a single binary package bundled with all required libraries and dependencies, and you can install it on any Linux distribution, regardless of its version and architecture. Similar to Snaps, there is also another tool called **Flatpak**. As you may already know, packaging distributed applications for different Linux distributions are quite time consuming and difficult process. Each distributed application has different set of libraries and dependencies for various Linux distributions. But, Flatpak, the new framework for desktop applications that completely reduces this burden. Now, you can build a single Flatpak app and install it on various operating systems. How cool, isn’t it? - -Also, the users don’t have to worry about the libraries and dependencies, everything is bundled within the app itself. Most importantly, Flaptpak apps are sandboxed and isolated from the rest of the host operating system, and other applications. Another notable feature is we can install multiple versions of the same application at the same time in the same system. For example, you can install VLC player version 2.1, 2.2, and 2.3 on the same system. So, the developers can test different versions of same application at a time. - -In this tutorial, we will see how to install Flatpak in GNU/Linux. - -### Install Flatpak - -Flatpak is available for many popular Linux distributions such as Arch Linux, Debian, Fedora, Gentoo, Red Hat, Linux Mint, openSUSE, Solus, Mageia and Ubuntu distributions. - -To install Flatpak on Arch Linux, run: -``` -$ sudo pacman -S flatpak - -``` - -Flatpak is available in the default repositories of Debian Stretch and newer. To install it, run: -``` -$ sudo apt install flatpak - -``` - -On Fedora, Flatpak is installed by default. All you have to do is enable enable Flathub as described in the next section. - -Just in case, it is not installed for any reason, run: -``` -$ sudo dnf install flatpak - -``` - -On RHEL 7, run: -``` -$ sudo yum install flatpak - -``` - -On Linux Mint 18.3, flatpak is installed by default. So, no setup required. - -On openSUSE Tumbleweed, Flatpak can also be installed using Zypper: -``` -$ sudo zypper install flatpak - -``` - -On Ubuntu, add the following repository and install Flatpak as shown below. -``` -$ sudo add-apt-repository ppa:alexlarsson/flatpak - -$ sudo apt update - -$ sudo apt install flatpak - -``` - -The Flatpak plugin for the Software app makes it possible to install apps without needing the command line. To install this plugin, run: -``` -$ sudo apt install gnome-software-plugin-flatpak - -``` - -For other Linux distributions, refer the official installation [**link**][2]. - -### Getting Started With Flatpak - -There are many popular applications such as Gimp, Kdenlive, Steam, Spotify, Visual studio code etc., available as flatpaks. - -Let us now see the basic usage of flatpak command. - -First of all, we need to add remote repositories. - -#### Adding Remote Repositories** - -**Enable Flathub Repository:** - -**Flathub** is nothing but a central repository where all flatpak applications available to users. To enable it, just run: -``` -$ sudo flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo - -``` - -Flathub is enough to install most popular apps. Just in case you wanted to try some GNOME apps, add the GNOME repository. - -**Enable GNOME Repository:** - -The GNOME repository contains all GNOME core applications. GNOME flatpak repository itself is available as two versions, **stable** and **nightly**. - -To add GNOME stable repository, run the following commands: -``` -$ wget https://sdk.gnome.org/keys/gnome-sdk.gpg - -$ sudo flatpak remote-add --gpg-import=gnome-sdk.gpg --if-not-exists gnome-apps https://sdk.gnome.org/repo-apps/ - -``` - -Applications in this repository require the **3.20 version of the org.gnome.Platform runtime**. - -To install the stable runtimes, run: -``` -$ sudo flatpak remote-add --gpg-import=gnome-sdk.gpg gnome https://sdk.gnome.org/repo/ - -``` - -To add the GNOME nightly apps repository, run: -``` -$ wget https://sdk.gnome.org/nightly/keys/nightly.gpg - -$ sudo flatpak remote-add --gpg-import=nightly.gpg --if-not-exists gnome-nightly-apps https://sdk.gnome.org/nightly/repo-apps/ - -``` - -Applications in this repository require the **nightly version of the org.gnome.Platform runtime**. - -To install the nightly runtimes, run: -``` -$ sudo flatpak remote-add --gpg-import=nightly.gpg gnome-nightly https://sdk.gnome.org/nightly/repo/ - -``` - -#### Listing Remotes - -To list all configured remote repositories, run: -``` -$ flatpak remotes -Name Options -flathub system -gnome system -gnome-apps system -gnome-nightly system -gnome-nightly-apps system - -``` - -As you can see, the above command lists the remotes that you have added in your system. It also lists whether the remote has been added per-user or system-wide. - -#### Removing Remotes - -To remove a remote, for example flathub, simply do; -``` -$ sudo flatpak remote-delete flathub - -``` - -Here **flathub** is remote name. - -#### Installing Flatpak Applications - -In this section, we will see how to install flatpak apps. To install a flatpak application - -To install an application, simply do: -``` -$ sudo flatpak install flathub com.spotify.Client - -``` - -All the apps in the GNOME stable repository uses the version name of “stable”. - -To install any Stable GNOME applications, for example **Evince** , run: -``` -$ sudo flatpak install gnome-apps org.gnome.Evince stable - -``` - -All the apps in the GNOME nightly repository uses the version name of “master”. - -For example, to install gedit, run: -``` -$ sudo flatpak install gnome-nightly-apps org.gnome.gedit master - -``` - -If you don’t want to install apps system-wide, you also can install flatpak apps per-user like below. -``` -$ flatpak install --user - -``` - -All installed apps will be stored in **$HOME/.var/app/** location. -``` -$ ls $HOME/.var/app/ -com.spotify.Client - -``` - -#### Running Flatpak Applications - -You can launch the installed applications at any time from the application launcher. From command line, you can run it, for example Spotify, using command: -``` -$ flatpak run com.spotify.Client - -``` - -#### Listing Applications - -To view the installed applications and runtimes, run: -``` -$ flatpak list - -``` - -To view only the applications, not run times, use this command instead. -``` -$ flatpak list --app - -``` - -You can also view the list of available applications and runtimes from all remotes using command: -``` -$ flatpak remote-ls - -``` - -To list only applications not runtimes, run: -``` -$ flatpak remote-ls --app - -``` - -To list applications and runtimes from a specific repository, for example **gnome-apps** , run: -``` -$ flatpak remote-ls gnome-apps - -``` - -To list only the applications from a remote repository, run: -``` -$ flatpak remote-ls flathub --app - -``` - -#### Updating Applications - -To update all your flatpak applications, run: -``` -$ flatpak update - -``` - -To update a specific application, we do: -``` -$ flatpak update com.spotify.Client - -``` - -#### Getting Details Of Applications - -To display the details of a installed application, run: -``` -$ flatpak info io.github.mmstick.FontFinder - -``` - -Sample output: -``` -Ref: app/io.github.mmstick.FontFinder/x86_64/stable -ID: io.github.mmstick.FontFinder -Arch: x86_64 -Branch: stable -Origin: flathub -Date: 2018-04-11 15:10:31 +0000 -Subject: Workaround appstream issues (391ef7f5) -Commit: 07164e84148c9fc8b0a2a263c8a468a5355b89061b43e32d95008fc5dc4988f4 -Parent: dbff9150fce9fdfbc53d27e82965010805f16491ec7aa1aa76bf24ec1882d683 -Location: /var/lib/flatpak/app/io.github.mmstick.FontFinder/x86_64/stable/07164e84148c9fc8b0a2a263c8a468a5355b89061b43e32d95008fc5dc4988f4 -Installed size: 2.5 MB -Runtime: org.gnome.Platform/x86_64/3.28 - -``` - -#### Removing Applications - -To remove a flatpak application, run: -``` -$ sudo flatpak uninstall com.spotify.Client - -``` - -For details, refer flatpak help section. -``` -$ flatpak --help - -``` - -And, that’s all for now. Hope you had basic idea about Flatpak. - -If you find this guide useful, please share it on your social, professional networks and support OSTechNix. - -More good stuffs to come. Stay tuned! - -Cheers! - - - --------------------------------------------------------------------------------- - -via: https://www.ostechnix.com/flatpak-new-framework-desktop-applications-linux/ - -作者：[SK][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://www.ostechnix.com/author/sk/ -[1]:http://www.ostechnix.com/introduction-ubuntus-snap-packages/ -[2]:https://flatpak.org/setup/ diff --git a/sources/tech/20180503 11 Methods To Find System-Server Uptime In Linux.md b/sources/tech/20180503 11 Methods To Find System-Server Uptime In Linux.md deleted file mode 100644 index 7a30127b07..0000000000 --- a/sources/tech/20180503 11 Methods To Find System-Server Uptime In Linux.md +++ /dev/null @@ -1,193 +0,0 @@ -11 Methods To Find System/Server Uptime In Linux -====== -Do you want to know, how long your Linux system has been running without downtime? when the system is up and what date. - -There are multiple commands is available in Linux to check server/system uptime and most of users prefer the standard and very famous command called `uptime` to get this details. - -Server uptime is not important for some people but it’s very important for server administrators when the server running with mission-critical applications such as online shopping portal, netbanking portal, etc,. - -It must be zero downtime because if there is a down time then it will impact badly to million users. - -As i told, many commands are available to check server uptime in Linux. In this tutorial we are going teach you how to check this using below 11 methods. - -Uptime means how long the server has been up since its last shutdown or reboot. - -The uptime command the fetch the details from `/proc` files and print the server uptime, the `/proc` file is not directly readable by humans. - -The below commands will print how long the system has been running and up. It also shows some additional information. - -### Method-1 : Using uptime Command - -uptime command will tell how long the system has been running. It gives a one line display of the following information. - -The current time, how long the system has been running, how many users are currently logged on, and the system load averages for the past 1, 5, and 15 minutes. -``` -# uptime - - 08:34:29 up 21 days, 5:46, 1 user, load average: 0.06, 0.04, 0.00 - -``` - -### Method-2 : Using w Command - -w command provides a quick summary of every user logged into a computer, what each user is currently doing, -and what load all the activity is imposing on the computer itself. The command is a one-command combination of several other Unix programs: who, uptime, and ps -a. -``` -# w - - 08:35:14 up 21 days, 5:47, 1 user, load average: 0.26, 0.09, 0.02 -USER TTY FROM [email protected] IDLE JCPU PCPU WHAT -root pts/1 103.5.134.167 08:34 0.00s 0.01s 0.00s w - -``` - -### Method-3 : Using top Command - -Top command is one of the basic command to monitor real-time system processes in Linux. It display system information and running processes information like uptime, average load, tasks running, number of users logged in, number of CPUs & cpu utilization, Memory & swap information. Run top command then hit E to bring the memory utilization in MB. - -**Suggested Read :** [TOP Command Examples to Monitor Server Performance][1] -``` -# top -c - -top - 08:36:01 up 21 days, 5:48, 1 user, load average: 0.12, 0.08, 0.02 -Tasks: 98 total, 1 running, 97 sleeping, 0 stopped, 0 zombie -Cpu(s): 0.0%us, 0.3%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st -Mem: 1872888k total, 1454644k used, 418244k free, 175804k buffers -Swap: 2097148k total, 0k used, 2097148k free, 1098140k cached - - PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND - 1 root 20 0 19340 1492 1172 S 0.0 0.1 0:01.04 /sbin/init - 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [kthreadd] - 3 root RT 0 0 0 0 S 0.0 0.0 0:00.00 [migration/0] - 4 root 20 0 0 0 0 S 0.0 0.0 0:34.32 [ksoftirqd/0] - 5 root RT 0 0 0 0 S 0.0 0.0 0:00.00 [stopper/0] - -``` - -### Method-4 : Using who Command - -who command displays a list of users who are currently logged into the computer. The who command is related to the command w, which provides the same information but also displays additional data and statistics. -``` -# who -b - -system boot 2018-04-12 02:48 - -``` - -### Method-5 : Using last Command - -The last command displays a list of last logged in users. Last searches back through the file /var/log/wtmp and displays a list of all users logged in (and out) since that file was created. -``` -# last reboot -F | head -1 | awk '{print $5,$6,$7,$8,$9}' - -Thu Apr 12 02:48:04 2018 - -``` - -### Method-6 : Using /proc/uptime File - -This file contains information detailing how long the system has been on since its last restart. The output of `/proc/uptime` is quite minimal. - -The first number is the total number of seconds the system has been up. The second number is how much of that time the machine has spent idle, in seconds. -``` -# cat /proc/uptime - -1835457.68 1809207.16 - -``` - -# date -d “$(Method-7 : Using tuptime Command - -Tuptime is a tool for report the historical and statistical running time of the system, keeping it between restarts. Like uptime command but with more interesting output. -``` -$ tuptime - -``` - -### Method-8 : Using htop Command - -htop is an interactive process viewer for Linux which was developed by Hisham using ncurses library. Htop have many of features and options compared to top command. - -**Suggested Read :** [Monitor system resources using Htop command][2] -``` -# htop - - CPU[| 0.5%] Tasks: 48, 5 thr; 1 running - Mem[||||||||||||||||||||||||||||||||||||||||||||||||||| 165/1828MB] Load average: 0.10 0.05 0.01 - Swp[ 0/2047MB] Uptime: 21 days, 05:52:35 - - PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command -29166 root 20 0 110M 2484 1240 R 0.0 0.1 0:00.03 htop -29580 root 20 0 11464 3500 1032 S 0.0 0.2 55:15.97 /bin/sh ./OSWatcher.sh 10 1 - 1 root 20 0 19340 1492 1172 S 0.0 0.1 0:01.04 /sbin/init - 486 root 16 -4 10780 900 348 S 0.0 0.0 0:00.07 /sbin/udevd -d - 748 root 18 -2 10780 932 360 S 0.0 0.0 0:00.00 /sbin/udevd -d - -``` - -### Method-9 : Using glances Command - -Glances is a cross-platform curses-based system monitoring tool written in Python. We can say all in one place, like maximum of information in a minimum of space. It uses psutil library to get information from your system. - -Glances capable to monitor CPU, Memory, Load, Process list, Network interface, Disk I/O, Raid, Sensors, Filesystem (and folders), Docker, Monitor, Alert, System info, Uptime, Quicklook (CPU, MEM, LOAD), etc,. - -**Suggested Read :** [Glances (All in one Place)– An Advanced Real Time System Performance Monitoring Tool for Linux][3] -``` -glances - -ubuntu (Ubuntu 17.10 64bit / Linux 4.13.0-37-generic) - IP 192.168.1.6/24 Uptime: 21 days, 05:55:15 - -CPU [|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| 90.6%] CPU - 90.6% nice: 0.0% ctx_sw: 4K MEM \ 78.4% active: 942M SWAP - 5.9% LOAD 2-core -MEM [||||||||||||||||||||||||||||||||||||||||||||||||||||||||| 78.0%] user: 55.1% irq: 0.0% inter: 1797 total: 1.95G inactive: 562M total: 12.4G 1 min: 4.35 -SWAP [|||| 5.9%] system: 32.4% iowait: 1.8% sw_int: 897 used: 1.53G buffers: 14.8M used: 749M 5 min: 4.38 - idle: 7.6% steal: 0.0% free: 431M cached: 273M free: 11.7G 15 min: 3.38 - -NETWORK Rx/s Tx/s TASKS 211 (735 thr), 4 run, 207 slp, 0 oth sorted automatically by memory_percent, flat view -docker0 0b 232b -enp0s3 12Kb 4Kb Systemd 7 Services loaded: 197 active: 196 failed: 1 -lo 616b 616b -_h478e48e 0b 232b CPU% MEM% VIRT RES PID USER NI S TIME+ R/s W/s Command - 63.8 18.9 2.33G 377M 2536 daygeek 0 R 5:57.78 0 0 /usr/lib/firefox/firefox -contentproc -childID 1 -isForBrowser -intPrefs 6:50|7:-1|19:0|34:1000|42:20|43:5|44:10|51 -DefaultGateway 83ms 78.5 10.9 3.46G 217M 2039 daygeek 0 S 21:07.46 0 0 /usr/bin/gnome-shell - 8.5 10.1 2.32G 201M 2464 daygeek 0 S 8:45.69 0 0 /usr/lib/firefox/firefox -new-window -DISK I/O R/s W/s 1.1 8.5 2.19G 170M 2653 daygeek 0 S 2:56.29 0 0 /usr/lib/firefox/firefox -contentproc -childID 4 -isForBrowser -intPrefs 6:50|7:-1|19:0|34:1000|42:20|43:5|44:10|51 -dm-0 0 0 1.7 7.2 2.15G 143M 2880 daygeek 0 S 7:10.46 0 0 /usr/lib/firefox/firefox -contentproc -childID 6 -isForBrowser -intPrefs 6:50|7:-1|19:0|34:1000|42:20|43:5|44:10|51 -sda1 9.46M 12K 0.0 4.9 1.78G 97.2M 6125 daygeek 0 S 1:36.57 0 0 /usr/lib/firefox/firefox -contentproc -childID 7 -isForBrowser -intPrefs 6:50|7:-1|19:0|34:1000|42:20|43:5|44:10|51 - -``` - -### Method-10 : Using stat Command - -stat command displays the detailed status of a particular file or a file system. -``` -# stat /var/log/dmesg | grep Modify - -Modify: 2018-04-12 02:48:04.027999943 -0400 - -``` - -### Method-11 : Using procinfo Command - -procinfo gathers some system data from the /proc directory and prints it nicely formatted on the standard output device. -``` -# procinfo | grep Bootup - -Bootup: Fri Apr 20 19:40:14 2018 Load average: 0.16 0.05 0.06 1/138 16615 - -``` - --------------------------------------------------------------------------------- - -via: https://www.2daygeek.com/11-methods-to-find-check-system-server-uptime-in-linux/ - -作者：[Magesh Maruthamuthu][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://www.2daygeek.com/author/magesh/ -[1]:https://www.2daygeek.com/top-command-examples-to-monitor-server-performance/ -[2]:https://www.2daygeek.com/htop-command-examples-to-monitor-system-resources/ -[3]:https://www.2daygeek.com/install-glances-advanced-real-time-linux-system-performance-monitoring-tool-on-centos-fedora-ubuntu-debian-opensuse-arch-linux/ diff --git a/sources/tech/20180514 An introduction to the Pyramid web framework for Python.md b/sources/tech/20180514 An introduction to the Pyramid web framework for Python.md new file mode 100644 index 0000000000..03a6fa6494 --- /dev/null +++ b/sources/tech/20180514 An introduction to the Pyramid web framework for Python.md @@ -0,0 +1,617 @@ +[#]: collector: (lujun9972) +[#]: translator: (Flowsnow) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: subject: (An introduction to the Pyramid web framework for Python) +[#]: via: (https://opensource.com/article/18/5/pyramid-framework) +[#]: author: (Nicholas Hunt-Walker https://opensource.com/users/nhuntwalker) +[#]: url: ( ) + +An introduction to the Pyramid web framework for Python +====== +In the second part in a series comparing Python frameworks, learn about Pyramid. + + +In the [first article][1] in this four-part series comparing different Python web frameworks, I explained how to create a To-Do List web application in the [Flask][2] web framework. In this second article, I'll do the same task with the [Pyramid][3] web framework. Future articles will look at [Tornado][4] and [Django][5]; as I go along, I'll explore more of the differences among them. + +### Installing, starting up, and doing configuration + +Self-described as "the start small, finish big, stay finished framework," Pyramid is much like Flask in that it takes very little effort to get it up and running. In fact, you'll recognize many of the same patterns as you build out this application. The major difference between the two, however, is that Pyramid comes with several useful utilities, which I'll describe shortly. + +To get started, create a virtual environment and install the package. + +``` +$ mkdir pyramid_todo +$ cd pyramid_todo +$ pipenv install --python 3.6 +$ pipenv shell +(pyramid-someHash) $ pipenv install pyramid +``` + +As with Flask, it's smart to create a `setup.py` file to make the app you build an easily installable Python distribution. + +``` +# setup.py +from setuptools import setup, find_packages + +requires = [ + 'pyramid', + 'paster_pastedeploy', + 'pyramid-ipython', + 'waitress' +] + +setup( + name='pyramid_todo', + version='0.0', + description='A To-Do List build with Pyramid', + author=' ', + author_email=' ', + keywords='web pyramid pylons', + packages=find_packages(), + include_package_data=True, + install_requires=requires, + entry_points={ + 'paste.app_factory': [ + 'main = todo:main', + ] + } +) +``` + +`entry_points` section near the end sets up entry points into the application that other services can use. This allows the `plaster_pastedeploy` package to access what will be the `main` function in the application for building an application object and serving it. (I'll circle back to this in a bit.) + +Thesection near the end sets up entry points into the application that other services can use. This allows thepackage to access what will be thefunction in the application for building an application object and serving it. (I'll circle back to this in a bit.) + +When you installed `pyramid`, you also gained a few Pyramid-specific shell commands; the main ones to pay attention to are `pserve` and `pshell`. `pserve` will take an INI-style configuration file specified as an argument and serve the application locally. `pshell` will also take a configuration file as an argument, but instead of serving the application, it'll open up a Python shell that is aware of the application and its internal configuration. + +The configuration file is pretty important, so it's worth a closer look. Pyramid can take its configuration from environment variables or a configuration file. To avoid too much confusion around what is where, in this tutorial you'll write most of your configuration in the configuration file, with only a select few, sensitive configuration parameters set in the virtual environment. + +Create a file called `config.ini` + +``` +[app:main] +use = egg:todo +pyramid.default_locale_name = en + +[server:main] +use = egg:waitress#main +listen = localhost:6543 +``` + +This says a couple of things: + + * The actual application will come from the `main` function located in the `todo` package installed in the environment + * To serve this app, use the `waitress` package installed in the environment and serve on localhost port 6543 + + + +When serving an application and working in development, it helps to set up logging so you can see what's going on. The following configuration will handle logging for the application: + +``` +# continuing on... +[loggers] +keys = root, todo + +[handlers] +keys = console + +[formatters] +keys = generic + +[logger_root] +level = INFO +handlers = console + +[logger_todo] +level = DEBUG +handlers = +qualname = todo + +[handler_console] +class = StreamHandler +args = (sys.stderr,) +level = NOTSET +formatter = generic + +[formatter_generic] +format = %(asctime)s %(levelname)-5.5s [%(name)s:%(lineno)s][%(threadName)s] %(message)s +``` + +In short, this configuration asks to log everything to do with the application to the console. If you want less output, set the logging level to `WARN` so a message will fire only if there's a problem. + +Because Pyramid is meant for an application that grows, plan out a file structure that could support that growth. Web applications can, of course, be built however you want. In general, the conceptual blocks you'll want to cover will contain: + + * **Models** for containing the code and logic for dealing with data representations + * **Views** for code and logic pertaining to the request-response cycle + * **Routes** for the paths for access to the functionality of your application + * **Scripts** for any code that might be used in configuration or management of the application itself + + + +Given the above, the file structure can look like so: + +``` +setup.py +config.ini +todo/ + __init__.py + models.py + routes.py + views.py + scripts/ +``` + +Much like Flask's `app` object, Pyramid has its own central configuration. It comes from its `config` module and is known as the `Configurator` object. This object will handle everything from route configuration to pointing to where models and views exist. All this is done in an inner directory called `todo` within an `__init__.py` file. + +``` +# todo/__init__.py + +from pyramid.config import Configurator + +def main(global_config, **settings): + """Returns a Pyramid WSGI application.""" + config = Configurator(settings=settings) + config.scan() + return config.make_wsgi_app() +``` + +The `main` function looks for some global configuration from your environment as well as any settings that came through the particular configuration file you provide when you run the application. It takes those settings and uses them to build an instance of the `Configurator` object, which (for all intents and purposes) is the factory for your application. Finally, `config.scan()` looks for any views you'd like to attach to your application that are marked as Pyramid views. + +Wow, that was a lot to configure. + +### Using routes and views + +Now that a chunk of the configuration is done, you can start adding functionality to the application. Functionality comes in the form of URL routes that external clients can hit, which then map to functions that Python can run. + +With Pyramid, all functionality must be added to the `Configurator` in some way, shape, or form. For example, say you want to build the same simple `hello_world` view that you built with Flask, mapping to the route of `/`. With Pyramid, you can register the `/` route with the `Configurator` using the `.add_route()` method. This method takes as arguments the name of the route that you want to add as well as the actual pattern that must be matched to access that route. For this case, add the following to your `Configurator`: + +``` +config.add_route('home', '/') +``` + +Until you create a view and attach it to that route, that path into your application sits open and alone. When you add the view, make sure to include the `request` object in the parameter list. Every Pyramid view must have the `request` object as its first parameter, as that's what's being passed as the first argument to the view when it's called by Pyramid. + +One similarity that Pyramid views share with Flask is that you can mark a function as a view with a decorator. Specifically, the `@view_config` decorator from `pyramid.view`. + +In `views.py`, build the view that you want to see in the world. + +``` +from pyramid.view import view_config + +@view_config(route_name="hello", renderer="string") +def hello_world(request): + """Print 'Hello, world!' as the response body.""" + return 'Hello, world!' +``` + +With the `@view_config` decorator, you have to at least specify the name of the route that will map to this particular view. You can stack `view_config` decorators on top of one another to map to multiple routes if you want, but you have to have at least one to connect view the view at all, and each one must include the name of a route. **[NOTE: Is "to connect view the view" phrased correctly?]** + +The other argument, `renderer`, is optional but not really. If you don't specify a renderer, you have to deliberately construct the HTTP response you want to send back to the client using the `Response` object from `pyramid.response`. By specifying the `renderer` as a string, Pyramid knows to take whatever is returned by this function and wrap it in that same `Response` object with the MIME type of `text/plain`. By default, Pyramid allows you to use `string` and `json` as renderers. If you've attached a templating engine to your application because you want to have Pyramid generate your HTML as well, you can point directly to your HTML template as your renderer. + +The first view is done. Here's what `__init__.py` looks like now with the attached route. + +``` +# in __init__.py +from pyramid.config import Configurator + +def main(global_config, **settings): + """Returns a Pyramid WSGI application.""" + config = Configurator(settings=settings) + config.add_route('hello', '/') + config.scan() + return config.make_wsgi_app() +``` + +Spectacular! Getting here was no easy feat, but now that you're set up, you can add functionality with significantly less difficulty. + +### Smoothing a rough edge + +Right now the application only has one route, but it's easy to see that a large application can have many dozens or even hundreds of routes. Containing them all in the same `main` function with your central configuration isn't really the best idea, because it would become cluttered. Thankfully, it's fairly easy to include routes with a few tweaks to the application. + +**One** : In the `routes.py` file, create a function called `includeme` (yes, it must actually be named this) that takes a configurator object as an argument. + +``` +# in routes.py +def includeme(config): + """Include these routes within the application.""" +``` + +**Two** : Move the `config.add_route` method call from `__init__.py` into the `includeme` function: + +``` +def includeme(config): + """Include these routes within the application.""" + config.add_route('hello', '/') +``` + +**Three** : Alert the Configurator that you need to include this `routes.py` file as part of its configuration. Because it's in the same directory as `__init__.py`, you can get away with specifying the import path to this file as `.routes`. + +``` +# in __init__.py +from pyramid.config import Configurator + +def main(global_config, **settings): + """Returns a Pyramid WSGI application.""" + config = Configurator(settings=settings) + config.include('.routes') + config.scan() + return config.make_wsgi_app() +``` + +### Connecting the database + +As with Flask, you'll want to persist data by connecting a database. Pyramid will leverage [SQLAlchemy][6] directly instead of using a specially tailored package. + +First get the easy part out of the way. `psycopg2` and `sqlalchemy` are required to talk to the Postgres database and manage the models, so add them to `setup.py`. + +``` +# in setup.py +requires = [ + 'pyramid', + 'pyramid-ipython', + 'waitress', + 'sqlalchemy', + 'psycopg2' +] +# blah blah other code +``` + +Now, you have a decision to make about how you'll include the database's URL. There's no wrong answer here; what you do will depend on the application you're building and how public your codebase needs to be. + +The first option will keep as much configuration in one place as possible by hard-coding the database URL into the `config.ini` file. One drawback is this creates a security risk for applications with a public codebase. Anyone who can view the codebase will be able to see the full database URL, including username, password, database name, and port. Another is maintainability; if you needed to change environments or the application's database location, you'd have to modify the `config.ini` file directly. Either that or you'll have to maintain one configuration file for each new environment, which adds the potential for discontinuity and errors in the application. **If you choose this option** , modify the `config.ini` file under the `[app:main]` heading to include this key-value pair: + +``` +sqlalchemy.url = postgres://localhost:5432/pyramid_todo +``` + +The second option specifies the location of the database URL when you create the `Configurator`, pointing to an environment variable whose value can be set depending on the environment where you're working. One drawback is that you're further splintering the configuration, with some in the `config.ini` file and some directly in the Python codebase. Another drawback is that when you need to use the database URL anywhere else in the application (e.g., in a database management script), you have to code in a second reference to that same environment variable (or set up the variable in one place and import from that location). **If you choose this option** , add the following: + +``` +# in __init__.py +import os +from pyramid.config import Configurator + +SQLALCHEMY_URL = os.environ.get('DATABASE_URL', '') + +def main(global_config, **settings): + """Returns a Pyramid WSGI application.""" + settings['sqlalchemy.url'] = SQLALCHEMY_URL # <-- important! + config = Configurator(settings=settings) + config.include('.routes') + config.scan() + return config.make_wsgi_app() +``` + +### Defining objects + +OK, so now you have a database. Now you need `Task` and `User` objects. + +Because it uses SQLAlchemy directly, Pyramid differs somewhat from Flash on how objects are built. First, every object you want to construct must inherit from SQLAlchemy's [declarative base class][7]. It'll keep track of everything that inherits from it, enabling simpler management of the database. + +``` +# in models.py +from sqlalchemy.ext.declarative import declarative_base + +Base = declarative_base() + +class Task(Base): + pass + +class User(Base): + pass +``` + +The columns, data types for those columns, and model relationships will be declared in much the same way as with Flask, although they'll be imported directly from SQLAlchemy instead of some pre-constructed `db` object. Everything else is the same. + +``` +# in models.py +from datetime import datetime +import secrets + +from sqlalchemy import ( + Column, Unicode, Integer, DateTime, Boolean, relationship +) +from sqlalchemy.ext.declarative import declarative_base + +Base = declarative_base() + +class Task(Base): + """Tasks for the To Do list.""" + id = Column(Integer, primary_key=True) + name = Column(Unicode, nullable=False) + note = Column(Unicode) + creation_date = Column(DateTime, nullable=False) + due_date = Column(DateTime) + completed = Column(Boolean, default=False) + user_id = Column(Integer, ForeignKey('user.id'), nullable=False) + user = relationship("user", back_populates="tasks") + + def __init__(self, *args, **kwargs): + """On construction, set date of creation.""" + super().__init__(*args, **kwargs) + self.creation_date = datetime.now() + +class User(Base): + """The User object that owns tasks.""" + id = Column(Integer, primary_key=True) + username = Column(Unicode, nullable=False) + email = Column(Unicode, nullable=False) + password = Column(Unicode, nullable=False) + date_joined = Column(DateTime, nullable=False) + token = Column(Unicode, nullable=False) + tasks = relationship("Task", back_populates="user") + + def __init__(self, *args, **kwargs): + """On construction, set date of creation.""" + super().__init__(*args, **kwargs) + self.date_joined = datetime.now() + self.token = secrets.token_urlsafe(64) +``` + +Note that there's no `config.include` line for `models.py` anywhere because it's not needed. A `config.include` line is needed only if some part of the application's configuration needs to be changed. This has only created two objects, inheriting from some `Base` class that SQLAlchemy gave us. + +### Initializing the database + +Now that the models are done, you can write a script to talk to and initialize the database. In the `scripts` directory, create two files: `__init__.py` and `initializedb.py`. The first is simply to turn the `scripts` directory into a Python package. The second is the script needed for database management. + +`initializedb.py` needs a function to set up the necessary tables in the database. Like with Flask, this script must be aware of the `Base` object, whose metadata keeps track of every class that inherits from it. The database URL is required to point to and modify its tables. + +As such, this database initialization script will work: + +``` +# initializedb.py +from sqlalchemy import engine_from_config +from todo import SQLALCHEMY_URL +from todo.models import Base + +def main(): + settings = {'sqlalchemy.url': SQLALCHEMY_URL} + engine = engine_from_config(settings, prefix='sqlalchemy.') + if bool(os.environ.get('DEBUG', '')): + Base.metadata.drop_all(engine) + Base.metadata.create_all(engine) +``` + +**Important note:** This will work only if you include the database URL as an environment variable in `todo/__init__.py` (the second option above). If the database URL was stored in the configuration file, you'll have to include a few lines to read that file. It will look something like this: + +``` +# alternate initializedb.py +from pyramid.paster import get_appsettings +from pyramid.scripts.common import parse_vars +from sqlalchemy import engine_from_config +import sys +from todo.models import Base + +def main(): + config_uri = sys.argv[1] + options = parse_vars(sys.argv[2:]) + settings = get_appsettings(config_uri, options=options) + engine = engine_from_config(settings, prefix='sqlalchemy.') + if bool(os.environ.get('DEBUG', '')): + Base.metadata.drop_all(engine) + Base.metadata.create_all(engine) +``` + +Either way, in `setup.py`, add a console script that will access and run this function. + +``` +# bottom of setup.py +setup( + # ... other stuff + entry_points={ + 'paste.app_factory': [ + 'main = todo:main', + ], + 'console_scripts': [ + 'initdb = todo.scripts.initializedb:main', + ], + } +) +``` + +When this package is installed, you'll have access to a new console script called `initdb`, which will construct the tables in your database. If the database URL is stored in the configuration file, you'll have to include the path to that file when you invoke the command. It'll look like `$ initdb /path/to/config.ini`. + +### Handling requests and the database + +Ok, here's where it gets a little deep. Let's talk about **transactions**. A "transaction," in an abstract sense, is any change made to an existing database. As with Flask, transactions are persisted no sooner than when they are committed. If changes have been made that haven't yet been committed, and you don't want those to occur (maybe there's an error thrown in the process), you can **rollback** a transaction and abort those changes. + +In Python, the [transaction package][8] allows you to interact with transactions as objects, which can roll together multiple changes into one single commit. `transaction` provides **transaction managers** , which give applications a straightforward, thread-aware way of handling transactions so all you need to think about is what to change. The `pyramid_tm` package will take the transaction manager from `transaction` and wire it up in a way that's appropriate for Pyramid's request-response cycle, attaching a transaction manager to every incoming request. + +Normally, with Pyramid the `request` object is populated when the route mapping to a view is accessed and the view function is called. Every view function will have a `request` object to work with**.** However, Pyramid allows you to modify its configuration to add whatever you might need to the `request` object. You can use the transaction manager that you'll be adding to the `request` to create a session with every request and add that session to the request. + +Yay, so why is this important? + +By attaching a transaction-managed session to the `request` object, when the view finishes processing the request, any changes made to the database session will be committed without you needing to explicitly commit**.** Here's what all these concepts look like in code. + +``` +# __init__.py +import os +from pyramid.config import Configurator +from sqlalchemy import engine_from_config +from sqlalchemy.orm import sessionmaker +import zope.sqlalchemy + +SQLALCHEMY_URL = os.environ.get('DATABASE_URL', '') + +def get_session_factory(engine): + """Return a generator of database session objects.""" + factory = sessionmaker() + factory.configure(bind=engine) + return factory + +def get_tm_session(session_factory, transaction_manager): + """Build a session and register it as a transaction-managed session.""" + dbsession = session_factory() + zope.sqlalchemy.register(dbsession, transaction_manager=transaction_manager) + return dbsession + +def main(global_config, **settings): + """Returns a Pyramid WSGI application.""" + settings['sqlalchemy.url'] = SQLALCHEMY_URL + settings['tm.manager_hook'] = 'pyramid_tm.explicit_manager' + config = Configurator(settings=settings) + config.include('.routes') + config.include('pyramid_tm') + session_factory = get_session_factory(engine_from_config(settings, prefix='sqlalchemy.')) + config.registry['dbsession_factory'] = session_factory + config.add_request_method( + lambda request: get_tm_session(session_factory, request.tm), + 'dbsession', + reify=True + ) + + config.scan() + return config.make_wsgi_app() +``` + +That looks like a lot, but it only did was what was explained above, plus it added an attribute to the `request` object called `request.dbsession`. + +A few new packages were included here, so update `setup.py` with those packages. + +``` +# in setup.py +requires = [ + 'pyramid', + 'pyramid-ipython', + 'waitress', + 'sqlalchemy', + 'psycopg2', + 'pyramid_tm', + 'transaction', + 'zope.sqlalchemy' +] +# blah blah other stuff +``` + +### Revisiting routes and views + +You need to make some real views that handle the data within the database and the routes that map to them. + +Start with the routes. You created the `routes.py` file to handle your routes but didn't do much beyond the basic `/` route. Let's fix that. + +``` +# routes.py +def includeme(config): + config.add_route('info', '/api/v1/') + config.add_route('register', '/api/v1/accounts') + config.add_route('profile_detail', '/api/v1/accounts/{username}') + config.add_route('login', '/api/v1/accounts/login') + config.add_route('logout', '/api/v1/accounts/logout') + config.add_route('tasks', '/api/v1/accounts/{username}/tasks') + config.add_route('task_detail', '/api/v1/accounts/{username}/tasks/{id}') +``` + +Now, it not only has static URLs like `/api/v1/accounts`, but it can handle some variable URLs like `/api/v1/accounts/{username}/tasks/{id}` where any variable in a URL will be surrounded by curly braces. + +To create the view to create an individual task in your application (like in the Flash example), you can use the `@view_config` decorator to ensure that it only takes incoming `POST` requests and check out how Pyramid handles data from the client. + +Take a look at the code, then check out how it differs from Flask's version. + +``` +# in views.py +from datetime import datetime +from pyramid.view import view_config +from todo.models import Task, User + +INCOMING_DATE_FMT = '%d/%m/%Y %H:%M:%S' + +@view_config(route_name="tasks", request_method="POST", renderer='json') +def create_task(request): + """Create a task for one user.""" + response = request.response + response.headers.extend({'Content-Type': 'application/json'}) + user = request.dbsession.query(User).filter_by(username=request.matchdict['username']).first() + if user: + due_date = request.json['due_date'] + task = Task( + name=request.json['name'], + note=request.json['note'], + due_date=datetime.strptime(due_date, INCOMING_DATE_FMT) if due_date else None, + completed=bool(request.json['completed']), + user_id=user.id + ) + request.dbsession.add(task) + response.status_code = 201 + return {'msg': 'posted'} +``` + +To start, note on the `@view_config` decorator that the only type of request you want this view to handle is a "POST" request. If you want to specify one type of request or one set of requests, provide either the string noting the request or a tuple/list of such strings. + +``` +response = request.response +response.headers.extend({'Content-Type': 'application/json'}) +# ...other code... +response.status_code = 201 +``` + +The HTTP response sent to the client is generated based on `request.response`. Normally, you wouldn't have to worry about that object. It would just produce a properly formatted HTTP response and you'd never know the difference. However, because you want to do something specific, like modify the response's status code and headers, you need to access that response and its methods/attributes. + +Unlike with Flask, you don't need to modify the view function parameter list just because you have variables in the route URL. Instead, any time a variable exists in the route URL, it is collected in the `matchdict` attribute of the `request`. It will exist there as a key-value pair, where the key will be the variable (e.g., "username") and the value will be whatever value was specified in the route (e.g., "bobdobson"). Regardless of what value is passed in through the route URL, it'll always show up as a string in the `matchdict`. So, when you want to pull the username from the incoming request URL, access it with `request.matchdict['username']` + +``` +user = request.dbsession.query(User).filter_by(username=request.matchdict['username']).first() +``` + +Querying for objects when using `sqlalchemy` directly differs significantly from what the `flask-sqlalchemy` package allows. Recall that when you used `flask-sqlalchemy` to build your models, the models inherited from the `db.Model` object. That `db` object already contained a connection to the database, so that connection could perform a straightforward operation like `User.query.all()`. + +That simple interface isn't present here, as the models in the Pyramid app inherit from `Base`, which is generated from `declarative_base()`, coming directly from the `sqlalchemy` package. It has no direct awareness of the database it'll be accessing. That awareness was attached to the `request` object via the app's central configuration as the `dbsession` attribute. Here's the code from above that did that: + +``` +config.add_request_method( + lambda request: get_tm_session(session_factory, request.tm), + 'dbsession', + reify=True +) +``` + +With all that said, whenever you want to query OR modify the database, you must work through `request.dbsession`. In the case, you want to query your "users" table for a specific user by using their username as their identifier. As such, the `User` object is provided as an argument to the `.query` method, then the normal SQLAlchemy operations are done from there. + +An interesting thing about this way of querying the database is that you can query for more than just one object or list of one type of object. You can query for: + + * Object attributes on their own, e.g., `request.dbsession.query(User.username)` would query for usernames + * Tuples of object attributes, e.g., `request.dbsession.query(User.username, User.date_joined)` + * Tuples of multiple objects, e.g., `request.dbsession.query(User, Task)` + + + +The data sent along with the incoming request will be found within the `request.json` dictionary. + +The last major difference is, because of all the machinations necessary to attach the committing of a session's activity to Pyramid's request-response cycle, you don't have to call `request.dbsession.commit()` at the end of your view. It's convenient, but there is one thing to be aware of moving forward. If instead of a new add to the database, you wanted to edit a pre-existing object in the database, you couldn't use `request.dbsession.commit()`. Pyramid will throw an error, saying something along the lines of "commit behavior is being handled by the transaction manager, so you can't call it on your own." And if you don't do something that resembles committing your changes, your changes won't stick. + +The solution here is to use `request.dbsession.flush()`. The job of `.flush()` is to signal to the database that some changes have been made and need to be included with the next commit. + +### Planning for the future + +At this point, you've set up most of the important parts of Pyramid, analogous to what you constructed with Flask in part one. There's much more that goes into an application, but much of the meat is handled here. Other view functions will follow similar formatting, and of course, there's always the question of security (which Pyramid has built in!). + +One of the major differences I see in the setup of a Pyramid application is that it has a much more intense configuration step than there is with Flask. I broke down those configuration steps to explain more about what's going on when a Pyramid application is constructed. However, it'd be disingenuous to act like I've known all of this since I started programming. My first experience with the Pyramid framework was with Pyramid 1.7 and its scaffolding system of `pcreate`, which builds out most of the necessary configuration, so all you need to do is think about the functionality you want to build. + +As of Pyramid 1.8, `pcreate` has been deprecated in favor of [cookiecutter][9], which effectively does the same thing. The difference is that it's maintained by someone else, and there are cookiecutter templates for more than just Pyramid projects. Now that we've gone through the components of a Pyramid project, I'd never endorse building a Pyramid project from scratch again when a cookiecutter template is available. Why do the hard work if you don't have to? In fact, the [pyramid-cookiecutter-alchemy][10] template would accomplish much of what I've written here (and a little bit more). It's actually similar to the `pcreate` scaffold I used when I first learned Pyramid. + +Learn more Python at [PyCon Cleveland 2018][11]. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/5/pyramid-framework + +作者：[Nicholas Hunt-Walker][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/nhuntwalker +[b]: https://github.com/lujun9972 +[1]: https://opensource.com/article/18/4/flask +[2]: http://flask.pocoo.org/ +[3]: https://trypyramid.com/ +[4]: http://www.tornadoweb.org/en/stable/ +[5]: https://www.djangoproject.com/ +[6]: https://www.sqlalchemy.org/ +[7]: http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/api.html#api-reference +[8]: http://zodb.readthedocs.io/en/latest/transactions.html +[9]: https://cookiecutter.readthedocs.io/en/latest/ +[10]: https://github.com/Pylons/pyramid-cookiecutter-alchemy +[11]: https://us.pycon.org/2018/ diff --git a/sources/tech/20180518 How to Manage Fonts in Linux.md b/sources/tech/20180518 How to Manage Fonts in Linux.md deleted file mode 100644 index 0faca7fa17..0000000000 --- a/sources/tech/20180518 How to Manage Fonts in Linux.md +++ /dev/null @@ -1,145 +0,0 @@ -How to Manage Fonts in Linux -====== - - - -Not only do I write technical documentation, I write novels. And because I’m comfortable with tools like GIMP, I also create my own book covers (and do graphic design for a few clients). That artistic endeavor depends upon a lot of pieces falling into place, including fonts. - -Although font rendering has come a long way over the past few years, it continues to be an issue in Linux. If you compare the look of the same fonts on Linux vs. macOS, the difference is stark. This is especially true when you’re staring at a screen all day. But even though the rendering of fonts has yet to find perfection in Linux, one thing that the open source platform does well is allow users to easily manage their fonts. From selecting, adding, scaling, and adjusting, you can work with fonts fairly easily in Linux. - -Here, I’ll share some of the tips I’ve depended on over the years to help extend my “font-ability” in Linux. These tips will especially help those who undertake artistic endeavors on the open source platform. Because there are so many desktop interfaces available for Linux (each of which deal with fonts in a different way), when a desktop environment becomes central to the management of fonts, I’ll be focusing primarily on GNOME and KDE. - -With that said, let’s get to work. - -### Adding new fonts - -For the longest time, I have been a collector of fonts. Some might say I have a bit of an obsession. And since my early days of using Linux, I’ve always used the same process for adding fonts to my desktops. There are two ways to do this: - - * Make the fonts available on a per-user basis. - - * Make the fonts available system-wide. - - - - -Because my desktops never have other users (besides myself), I only ever work with fonts on a per-user basis. However, I will show you how to do both. First, let’s see how to add fonts on a per-user basis. The first thing you must do is find fonts. Both True Type Fonts (TTF) and Open Type Fonts (OTF) can be added. I add fonts manually. Do this is, I create a new hidden directory in ~/ called ~/.fonts. This can be done with the command: -``` -mkdir ~/.fonts - -``` - -With that folder created, I then move all of my TTF and OTF files into the directory. That’s it. Every font you add into that directory will now be available for use to your installed apps. But remember, those fonts will only be available to that one user. - -If you want to make that collection of fonts available to all, here’s what you do: - - 1. Open up a terminal window. - - 2. Change into the directory housing all of your fonts. - - 3. Copy all of those fonts with the commands sudo cp *.ttf *.TTF /usr/share/fonts/truetype/ and sudo cp *.otf *.OTF /usr/share/fonts/opentype - - - - -The next time a user logs in, they’ll have access to all those glorious fonts. - -### GUI Font Managers - -There are a few ways to manage your fonts in Linux, via GUI. How it’s done will depend on your desktop environment. Let’s examine KDE first. With the KDE that ships with Kubuntu 18.04, you’ll find a Font Management tool pre-installed. Open that tool and you can easily add, remove, enable, and disable fonts (as well as get information about all of the installed fonts. This tool also makes it easy for you to add and remove fonts for personal and system-wide use. Let’s say you want to add a particular font for personal usage. To do this, download your font and then open up the Font Management tool. In this tool (Figure 1), click on Personal Fonts and then click the + Add button. - - -![adding fonts][2] - -Figure 1: Adding personal fonts in KDE. - -[Used with permission][3] - -Navigate to the location of your fonts, select them, and click Open. Your fonts will then be added to the Personal section and are immediately available for you to use (Figure 2). - - -![KDE Font Manager][5] - -Figure 2: Fonts added with the KDE Font Manager. - -[Used with permission][3] - -To do the same thing in GNOME requires the installation of an application. Open up either GNOME Software or Ubuntu Software (depending upon the distribution you’re using) and search for Font Manager. Select Font Manager and then click the Install button. Once the software is installed, launch it from the desktop menu. With the tool open, let’s install fonts on a per-user basis. Here’s how: - - 1. Select User from the left pane (Figure 3). - - 2. Click the + button at the top of the window. - - 3. Navigate to and select the downloaded fonts. - - 4. Click Open. - - - - -![Adding fonts ][7] - -Figure 3: Adding fonts in GNOME. - -[Used with permission][3] - -### Tweaking fonts - -There are three concepts you must first understand: - - * **Font Hinting:** The use of mathematical instructions to adjust the display of a font outline so that it lines up with a rasterized grid. - - * **Anti-aliasing:** The technique used to add greater realism to a digital image by smoothing jagged edges on curved lines and diagonals. - - * **Scaling factor:** **** A scalable unit that allows you to multiple the point size of a font. So if you’re font is 12pt and you have an scaling factor of 1, the font size will be 12pt. If your scaling factor is 2, the font size will be 24pt. - - - - -Let’s say you’ve installed your fonts, but they don’t look quite as good as you’d like. How do you tweak the appearance of fonts? In both the KDE and GNOME desktops, you can make a few adjustments. One thing to consider with the tweaking of fonts is that taste is very much subjective. You might find yourself having to continually tweak until you get the fonts looking exactly how you like (dictated by your needs and particular taste). Let’s first look at KDE. - -Open up the System Settings tool and clock on Fonts. In this section, you can not only change various fonts, you can also enable and configure both anti-aliasing and enable font scaling factor (Figure 4). - - -![Configuring fonts][9] - -Figure 4: Configuring fonts in KDE. - -[Used with permission][3] - -To configure anti-aliasing, select Enabled from the drop-down and then click Configure. In the resulting window (Figure 5), you can configure an exclude range, sub-pixel rendering type, and hinting style. - -Once you’ve made your changes, click Apply. Restart any running applications and the new settings will take effect. - -To do this in GNOME, you have to have either use Font Manager or GNOME Tweaks installed. For this, GNOME Tweaks is the better tool. If you open the GNOME Dash and cannot find Tweaks installed, open GNOME Software (or Ubuntu Software), and install GNOME Tweaks. Once installed, open it and click on the Fonts section. Here you can configure hinting, anti-aliasing, and scaling factor (Figure 6). - -![Tweaking fonts][11] - -Figure 6: Tweaking fonts in GNOME. - -[Used with permission][3] - -### Make your fonts beautiful - -And that’s the gist of making your fonts look as beautiful as possible in Linux. You may not see a macOS-like rendering of fonts, but you can certainly improve the look. Finally, the fonts you choose will have a large impact on how things look. Make sure you’re installing clean, well-designed fonts; otherwise, you’re fighting a losing battle. - -Learn more about Linux through the free ["Introduction to Linux" ][12] course from The Linux Foundation and edX. - --------------------------------------------------------------------------------- - -via: https://www.linux.com/learn/intro-to-linux/2018/5/how-manage-fonts-linux - -作者：[Jack Wallen][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://www.linux.com/users/jlwallen -[2]:https://www.linux.com/sites/lcom/files/styles/rendered_file/public/fonts_1.jpg?itok=7yTTe6o3 (adding fonts) -[3]:https://www.linux.com/licenses/category/used-permission -[5]:https://www.linux.com/sites/lcom/files/styles/rendered_file/public/fonts_2.jpg?itok=_g0dyVYq (KDE Font Manager) -[7]:https://www.linux.com/sites/lcom/files/styles/rendered_file/public/fonts_3.jpg?itok=8o884QKs (Adding fonts ) -[9]:https://www.linux.com/sites/lcom/files/styles/rendered_file/public/fonts_4.jpg?itok=QJpPzFED (Configuring fonts) -[11]:https://www.linux.com/sites/lcom/files/styles/rendered_file/public/fonts_6.jpg?itok=4cQeIW9C (Tweaking fonts) -[12]:https://training.linuxfoundation.org/linux-courses/system-administration-training/introduction-to-linux diff --git a/sources/tech/20180523 How to dual-boot Linux and Windows.md b/sources/tech/20180523 How to dual-boot Linux and Windows.md deleted file mode 100644 index 372097c866..0000000000 --- a/sources/tech/20180523 How to dual-boot Linux and Windows.md +++ /dev/null @@ -1,224 +0,0 @@ -translating by Auk7F7 -How to dual-boot Linux and Windows -====== - - - -Even though Linux is a great operating system with widespread hardware and software support, the reality is that sometimes you have to use Windows, perhaps due to key apps that won't run under Linux. Thankfully, dual-booting Windows and Linux is very straightforward—and I'll show you how to set it up, with Windows 10 and Ubuntu 18.04, in this article. - -Before you get started, make sure you've backed up your computer. Although the dual-boot setup process is not very involved, accidents can still happen. So take the time to back up your important files in case chaos theory comes into play. In addition to backing up your files, consider taking an image backup of the disk as well, though that's not required and can be a more advanced process. - -### Prerequisites - -To get started, you will need the following five items: - -#### 1\. Two USB flash drives (or DVD-Rs) - -I recommend installing Windows and Ubuntu via flash drives since they're faster than DVDs. It probably goes without saying, but creating bootable media erases everything on the flash drive. Therefore, make sure the flash drives are empty or contain data you don't care about losing. - -If your machine doesn't support booting from USB, you can create DVD media instead. Unfortunately, because no two computers seem to have the same DVD-burning software, I can't walk you through that process. However, if your DVD-burning application has an option to burn from an ISO image, that's the option you need. - -#### 2\. A Windows 10 license - -If Windows 10 came with your PC, the license will be built into the computer, so you don't need to worry about entering it during installation. If you bought the retail edition, you should have a product key, which you will need to enter during the installation process. - -#### 3\. Windows 10 Media Creation Tool - -Download and launch the Windows 10 [Media Creation Tool][1]. Once you launch the tool, it will walk you through the steps required to create the Windows media on a USB or DVD-R. Note: Even if you already have Windows 10 installed, it's a good idea to create bootable media anyway, just in case something goes wrong and you need to reinstall it. - -#### 4\. Ubuntu 18.04 installation media - -Download the [Ubuntu 18.04][2] ISO image. - -#### 5\. Etcher software (for making a bootable Ubuntu USB drive) - -For creating bootable media for any Linux distribution, I recommend [Etcher][3]. Etcher works on all three major operating systems (Linux, MacOS, and Windows) and is careful not to let you overwrite your current operating system partition. - -Once you have downloaded and launched Etcher, click Select image, and point it to the Ubuntu ISO you downloaded in step 4. Next, click Select drive to choose your flash drive, and click Flash! to start the process of turning a flash drive into an Ubuntu installer. (If you're using a DVD-R, use your computer's DVD-burning software instead.) - -### Install Windows and Ubuntu - -You should be ready to begin. At this point, you should have accomplished the following: - - * Backed up your important files - * Created Windows installation media - * Created Ubuntu installation media - - - -There are two ways of going about the installation. First, if you already have Windows 10 installed, you can have the Ubuntu installer resize the partition, and the installation will proceed in the empty space. Or, if you haven't installed Windows 10, install it on a smaller partition you can set up during the installation process. (I'll describe how to do that below.) The second way is preferred and less error-prone. There's a good chance you won't have any issues either way, but installing Windows manually and giving it a smaller partition, then installing Ubuntu, is the easiest way to go. - -If you already have Windows 10 on your computer, skip the following Windows installation instructions and proceed to Installing Ubuntu. - -#### Installing Windows - -Insert the Windows installation media you created into your computer and boot from it. How you do this depends on your computer, but most have a key you can press to initiate the boot menu. On a Dell PC for example, that key is F12. If the flash drive doesn't show up as an option, you may need to restart the computer. Sometimes it will show up only if you've inserted the media before turning on the computer. If you see a message like, "press any key to boot from the installation media," press a key. You should see the following screen. Select your language and keyboard style and click Next. - -![Windows setup][5] - -Click on Install now to start the Windows installer. - -On the next screen, it will ask for your product key. If you don't have one because Windows 10 came with your PC, select "I don't have a product key." It should automatically activate after the installation once it catches up with updates. If you do have a product key, type that in and click Next. - - -![Enter product key][7] - - -Select which version of Windows you want to install. If you have a retail copy, the label will tell you what version you have. Otherwise, it is typically located with the documentation that came with your computer. In most cases, it's going to be either Windows 10 Home or Windows 10 Pro. Most PCs that come with the Home edition have a label that simply reads "Windows 10," while Pro is clearly marked. - - -![Select Windows version][10] - - -Accept the license agreement by checking the box, then click Next. - - -![Accept license terms][12] - - -After accepting the agreement, you have two installation options available. Choose the second option, Custom: Install Windows only (advanced). - - -![Select type of Windows installation][14] - - -The next screen should show your current hard disk configuration. - - -![Hard drive configuration][16] - - -Your results will probably look different than mine. I have never used this hard disk before, so it's completely unallocated. You will probably see one or more partitions for your current operating system. Highlight each partition and remove it. - -At this point, your screen will show your entire disk as unallocated. To continue, create a new partition. - - -![Create a new partition][18] - - -Here you can see that I divided the drive in half (or close enough) by creating a partition of 81,920MB (which is close to half of 160GB). Give Windows at least 40GB, preferably 64GB or more. Leave the rest of the drive unallocated, as that's where you'll install Ubuntu later. - -Your results will look similar to this: - - -![Leaving a partition with unallocated space][20] - - -Confirm the partitioning looks good to you and click Next. Windows will begin installing. - - -![Installing Windows][22] - - -If your computer successfully boots into Windows, you're all set to move on to the next step. - -![Windows desktop][24] - - -#### Installing Ubuntu - -Whether it was already there or you worked through the steps above, at this point you should have Windows installed. Now use the Ubuntu installation media you created earlier to boot into Ubuntu. Go ahead and insert the media and boot your computer from it. Again, the exact sequence of keys to access the boot menu varies from one computer to another, so check your documentation if you're not sure. If all goes well, you see the following screen once the media finishes loading: - - -![Ubuntu installation welcome screen][26] - - -Here, you can select between Try Ubuntu or Install Ubuntu. Don't install just yet; instead, click Try Ubuntu. After it finishes loading, you should see the Ubuntu desktop. - - -![Ubuntu desktop][28] - -By clicking Try Ubuntu, you have opted to try out Ubuntu before you install it. Here, in Live mode, you can play around with Ubuntu and make sure everything works before you commit to the installation. Ubuntu works with most PC hardware, but it's always better to test it out beforehand. Make sure you can access the internet and get audio and video playback. Going to YouTube and playing a video is a good way of doing all of that at once. If you need to connect to a wireless network, click on the networking icon at the top-right of the screen. There, you can find a list of wireless networks and connect to yours. - -Once you're ready to go, double-click on the Install Ubuntu 18.04 LTS icon on the desktop to launch the installer. - -Choose the language you want to use for the installation process, then click Continue. - - -![Select language in Ubuntu][30] - - -Next, choose the keyboard layout. Once you've made your selection, click Continue. - - -![Select keyboard in Ubuntu][32] - -You have a few options on the screen below. One, you can choose a Normal or a Minimal installation. For most people, the Normal installation is ideal. Advanced users may want to do a Minimal install instead, which has fewer software applications installed by default. In addition, you can choose to download updates and whether or not to include third-party software and drivers. I recommend checking both of those boxes. When done, click Continue. - - -![Choose Ubuntu installation options][34] - -The next screen asks whether you want to erase the disk or set up a dual-boot. Since you're dual-booting, choose Install Ubuntu alongside Windows 10. Click Install Now. - - -![install Ubuntu alongside Windows][36] - - -The following screen may appear. If you installed Windows from scratch and left unallocated space on the disk, Ubuntu will automatically set itself up in the empty space, so you won't see this screen. If you already had Windows 10 installed and it's taking up the entire drive, this screen will appear and give you an option to select a disk at the top. If you have just one disk, you can choose how much space to steal from Windows and apply to Ubuntu. You can drag the vertical line in the middle left and right with your mouse to take space away from one and gives it to the other. Adjust this exactly the way you want it, then click Install Now. - - -![Allocate drive space][38] - - -You should see a confirmation screen indicating what Ubuntu plans on doing. If everything looks right, click Continue. - -Ubuntu is now installing in the background. You still have some configuration to do, though. While Ubuntu tries its best to figure out your location, you can click on the map to narrow it down to ensure your time zone and other things are set correctly. - -Next, fill in the user account information: your name, computer name, username, and password. Click Continue when you're done. - -There you have it! The installation is complete. Go ahead and reboot the PC. - -If all went according to plan, you should see a screen similar to this when your computer restarts. Choose Ubuntu or Windows 10; the other options are for troubleshooting, so I won't go into them. - -Try booting into both Ubuntu and Windows to test them out and make sure everything works as expected. If it does, you now have both Windows and Ubuntu installed on your computer. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/5/dual-boot-linux - -作者：[Jay LaCroix][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://opensource.com/users/jlacroix -[1]:https://www.microsoft.com/en-us/software-download/windows10 -[2]:https://www.ubuntu.com/download/desktop -[3]:http://www.etcher.io -[4]:/file/397066 -[5]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_01.png (Windows setup) -[6]:/file/397076 -[7]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_03.png (Enter product key) -[8]:data:image/gif;base64,R0lGODlhAQABAPABAP///wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw== (Click and drag to move) -[9]:/file/397081 -[10]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_04.png (Select Windows version) -[11]:/file/397086 -[12]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_05.png (Accept license terms) -[13]:/file/397091 -[14]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_06.png (Select type of Windows installation) -[15]:/file/397096 -[16]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_07.png (Hard drive configuration) -[17]:/file/397101 -[18]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_08.png (Create a new partition) -[19]:/file/397106 -[20]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_09.png (Leaving a partition with unallocated space) -[21]:/file/397111 -[22]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_10.png (Installing Windows) -[23]:/file/397116 -[24]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_11.png (Windows desktop) -[25]:/file/397121 -[26]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_12.png (Ubuntu installation welcome screen) -[27]:/file/397126 -[28]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_13.png (Ubuntu desktop) -[29]:/file/397131 -[30]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_15.png (Select language in Ubuntu) -[31]:/file/397136 -[32]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_16.png (Select keyboard in Ubuntu) -[33]:/file/397141 -[34]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_17.png (Choose Ubuntu installation options) -[35]:/file/397146 -[36]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_18.png (Install Ubuntu alongside Windows) -[37]:/file/397151 -[38]:https://opensource.com/sites/default/files/uploads/linux-dual-boot_18b.png (Allocate drive space) diff --git a/sources/tech/20180525 How to Set Different Wallpaper for Each Monitor in Linux.md b/sources/tech/20180525 How to Set Different Wallpaper for Each Monitor in Linux.md deleted file mode 100644 index 386149400c..0000000000 --- a/sources/tech/20180525 How to Set Different Wallpaper for Each Monitor in Linux.md +++ /dev/null @@ -1,89 +0,0 @@ -How to Set Different Wallpaper for Each Monitor in Linux -====== -**Brief: If you want to display different wallpapers on multiple monitors on Ubuntu 18.04 or any other Linux distribution with GNOME, MATE or Budgie desktop environment, this nifty tool will help you achieve this.** - -Multi-monitor setup often leads to multiple issues on Linux but I am not going to discuss those issues in this article. I have rather a positive article on multiple monitor support on Linux. - -If you are using multiple monitor, perhaps you would like to setup a different wallpaper for each monitor. I am not sure about other Linux distributions and desktop environments, but Ubuntu with [GNOME desktop][1] doesn’t provide this functionality on its own. - -Fret not! In this quick tutorial, I’ll show you how to set a different wallpaper for each monitor on Linux distributions with GNOME desktop environment. - -### Setting up different wallpaper for each monitor on Ubuntu 18.04 and other Linux distributions - -![Different wallaper on each monitor in Ubuntu][2] - -I am going to use a nifty tool called [HydraPaper][3] for setting different backgrounds on different monitors. HydraPaper is a [GTK][4] based application to set different backgrounds for each monitor in [GNOME desktop environment][5]. - -It also supports on [MATE][6] and [Budgie][7] desktop environments. Which means Ubuntu MATE and [Ubuntu Budgie][8] users can also benefit from this application. - -#### Install HydraPaper on Linux using FlatPak - -HydraPaper can be installed easily using [FlatPak][9]. Ubuntu 18.04 already provides support for FlatPaks so all you need to do is to download the application file and double click on it to open it with the GNOME Software Center. - -You can refer to this article to learn [how to enable FlatPak support][10] on your distribution. Once you have the FlatPak support enabled, just download it from [FlatHub][11] and install it. - -[Download HydraPaper][12] - -#### Using HydraPaper for setting different background on different monitors - -Once installed, just look for HydraPaper in application menu and start the application. You’ll see images from your Pictures folder here because by default the application takes images from the Pictures folder of the user. - -You can add your own folder(s) where you keep your wallpapers. Do note that it doesn’t find images recursively. If you have nested folders, it will only show images from the top folder. - -![Setting up different wallpaper for each monitor on Linux][13] - -Using HydraPaper is absolutely simple. Just select the wallpapers for each monitor and click on the apply button at the top. You can easily identify external monitor(s) termed with HDMI. - -![Setting up different wallpaper for each monitor on Linux][14] - -You can also add selected wallpapers to ‘Favorites’ for quick access. Doing this will move the ‘favorite wallpapers’ from Wallpapers tab to Favorites tab. - -![Setting up different wallpaper for each monitor on Linux][15] - -You don’t need to start HydraPaper at each boot. Once you set different wallpaper for different monitor, the settings are saved and you’ll see your chosen wallpapers even after restart. This would be expected behavior of course but I thought I would mention the obvious. - -One big downside of HydraPaper is in the way it is designed to work. You see, HydraPaper combines your selected wallpapers into one single image and stretches it across the screens giving an impression of having different background on each display. And this becomes an issue when you remove the external display. - -For example, when I tried using my laptop without the external display, it showed me an background image like this. - -![Dual Monitor wallpaper HydraPaper][16] - -Quite obviously, this is not what I would expect. - -#### Did you like it? - -HydraPaper makes setting up different backgrounds on different monitors a painless task. It supports more than two monitors and monitors with different orientation. Simple interface with only the required features makes it an ideal application for those who always use dual monitors. - -How do you set different wallpaper for different monitor on Linux? Do you think HydraPaper is an application worth installing? - -Do share your views and if you find this article, please share it on various social media channels such as Twitter and [Reddit][17]. - --------------------------------------------------------------------------------- - -via: https://itsfoss.com/wallpaper-multi-monitor/ - -作者：[Abhishek Prakash][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://itsfoss.com/author/abhishek/ -[1]:https://www.gnome.org/ -[2]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/05/multi-monitor-wallpaper-setup-800x450.jpeg -[3]:https://github.com/GabMus/HydraPaper -[4]:https://www.gtk.org/ -[5]:https://itsfoss.com/gnome-tricks-ubuntu/ -[6]:https://mate-desktop.org/ -[7]:https://budgie-desktop.org/home/ -[8]:https://itsfoss.com/ubuntu-budgie-18-review/ -[9]:https://flatpak.org -[10]:https://flatpak.org/setup/ -[11]:https://flathub.org -[12]:https://flathub.org/apps/details/org.gabmus.hydrapaper -[13]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/05/different-wallpaper-each-monitor-hydrapaper-2-800x631.jpeg -[14]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/05/different-wallpaper-each-monitor-hydrapaper-1.jpeg -[15]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/05/different-wallpaper-each-monitor-hydrapaper-3.jpeg -[16]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/05/hydra-paper-dual-monitor-800x450.jpeg -[17]:https://www.reddit.com/r/LinuxUsersGroup/ diff --git a/sources/tech/20180527 Streaming Australian TV Channels to a Raspberry Pi.md b/sources/tech/20180527 Streaming Australian TV Channels to a Raspberry Pi.md new file mode 100644 index 0000000000..ac756223f1 --- /dev/null +++ b/sources/tech/20180527 Streaming Australian TV Channels to a Raspberry Pi.md @@ -0,0 +1,209 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Streaming Australian TV Channels to a Raspberry Pi) +[#]: via: (https://blog.dxmtechsupport.com.au/streaming-australian-tv-channels-to-a-raspberry-pi/) +[#]: author: (James Mawson https://blog.dxmtechsupport.com.au/author/james-mawson/) + +Streaming Australian TV Channels to a Raspberry Pi +====== + +If you’re anything like me, it’s been years since you’ve even thought about hooking an antenna to your television. With so much of the good stuff available by streaming and download, it’s easy go a very long time without even thinking about free-to-air TV. + +But every now and again, something comes up – perhaps the cricket, news and current affairs shows, the FIFA World Cup – where the easiest thing would be to just chuck on the telly. + +When I first started tinkering with the Raspberry Pi as a gaming and media centre platform, the standard advice for watching broadcast TV always seemed to involve an antenna and a USB TV tuner. + +Which I guess is fine if you can be arsed. + +But what if you utterly can’t? + +What if you bitterly resent the idea of more clutter, more cords to add to the mess, more stuff to buy? What if every USB port is precious and jealously guarded for your keyboard, mouse, game controllers and removable storage? What if the wall port for your roof antenna is in a different room? + +That’s all a bit of a hassle for a thing you might use only a few times a year. + +In 2018, shouldn’t we just be able to stream free TV from the internet? + +It turns out that, yes, we can access legal and high quality TV streams from any Australian IP using [Freeview][1]. And thanks to a cool Kodi Add-on by [Matt Huisman][2], it’s now really easy to access this service from a Raspberry Pi. + +I’ve tested this to work on a Model 3 B+ running Retropie 4.4 and Kodi 17.6. But it should work similarly for other models and operating systems, so long as you’re using a reasonably up-to-date version of Kodi. + +Let’s jump right in. + +### If You Already Have Kodi Installed + +If you’re already using your Raspberry Pi to watch movies and TV shows, there’s a good chance you’ve already installed Kodi. + +Most Raspberry Pi operating systems intended for media centre use – such as OSMC or Xbian – come with Kodi installed by default. + +It’s fairly easy to get running on other Linux operating systems, and you might have already installed it there too. + +If your version of Kodi is more than a year or so old, it might be an idea to update it. The following instructions are written for the interface on Kodi 17 (Krypton). + +You can do that by typing the following commands at the command line: + +``` +sudo apt-get update +sudo apt-get upgrade +``` + +And now you can skip ahead to the next section. + +### Installing Kodi + +Installing Kodi on Retropie and other versions of Raspbian is fairly simple. Other Linux operating systems should be able to run it, perhaps with a bit of coaxing. + +You will need to be connected to the internet to install it. + +If you’re using something, such as Risc OS – you probably can’t install kodi. You will need to either swap in another SD card, or use a boot loader to boot into a media centre OS for your TV viewing. + +#### Installing Kodi on Retropie + +It’s really easy to install Kodi using the Retropie menu system. + +Here’s how: + + 1. Navigate to the Retropie main screen – that’s that horizontal menu where you can scroll left and right through all your different consoles + 2. Select “Retropie” + 3. Select “Retropie setup” + 4. Select “Manage Packages” + 5. Select “Manage Optional Packages” + 6. Scroll down and select “Kodi” + 7. Select “Install from Binary” + + + +This will take a minute or two to install. Once it’s installed, you can exit out of the Retropie Setup screen. When you next restart Retropie, you will see Kodi under the “Ports” section of the Retropie main screen. + +#### Installing Kodi on Raspbian + +If you’re running Raspbian without Retropie. But that’s okay, because it’s pretty easy to do it from the command line + +Just type: + +``` +sudo apt-get update +sudo apt-get install kodi +``` + +At this point you have a vanilla installation of Kodi. You can run it by typing: + +``` +kodi +``` + +It’s possible to delve a lot further into setting up Kodi from the command line. Check out [this guide][3] if you’re interested. + +If not, what you’ve just installed will work just fine. + +#### Installing Kodi on Other Versions of Linux + +If you’re using a different flavour of Linux, such as Pidora or Arch Linux ARM, then the above might or might not work – I’m not really sure, because I don’t really use these operating systems. + +If you get stuck, it might be worth a look at the [how-to guide][4] on the Kodi wiki. + +#### Dual Booting a Media Centre OS + +If your operating system of choice isn’t suitable for Kodi – or is just too confusing and difficult to figure out – it might be easiest to use a boot loader for multiple operating systems on the one SD card. + +You can set this up using an OS installer like [PINN][5]. + +Using PINN, you can install a media centre OS like [OSMC][6] to use Kodi – it will be installed with the operating system – and then your preferred OS for your other uses. + +It’s even possible to [move your existing OS over][7]. + +### Adding Australian TV Channels to Kodi + +With Kodi installed and running, you’ve got a pretty good media player for the files on your network and hard drive. + +But we need to install an add-on if we want to use it to chuck on the telly. This only takes a minute or so. + +#### Installing Matt Huisman’s Kodi Repository + +Ready? Let’s get started. + + 1. Open Kodi + 2. Click the cog icon at the top left to enter the settings + 3. Click “System Settings” + 4. Select “Add-ons” + 5. Make sure that “Unknown Sources” is enabled + 6. Right click anywhere on the screen to navigate back to the settings menu + 7. Click “File Manager” + 8. Click “Add Source” + 9. Double-click “Add Source” + 10. Select “ ” + 11. Type in exactly ** -a -G photos -sudo usermod guest -a -G photos - -``` - -You may have to log out and log back in to see the changes, but, when you do, running `groups` will show _photos_ as one of the groups you belong to. - -A couple of things to point out about the `usermod` command shown above. First: Be careful not to use the `-g` option instead of `-G`. The `-g` option changes your primary group and could lock you out of your stuff if you use it by accident. `-G`, on the other hand, _adds_ you to the groups listed and doesn't mess with the primary group. If you want to add your user to more groups than one, list them one after another, separated by commas, no spaces, after `-G`: -``` -sudo usermod -a -G photos,pizza,spaceforce - -``` - -Second: Be careful not to forget the `-a` parameter. The `-a` parameter stands for _append_ and attaches the list of groups you pass to `-G` to the ones you already belong to. This means that, if you don't include `-a`, the list of groups you already belong to, will be overwritten, again locking you out from stuff you need. - -Neither of these are catastrophic problems, but it will mean you will have to add your user back manually to all the groups you belonged to, which can be a pain, especially if you have lost access to the _sudo_ and _wheel_ group. - -### Permits, Please! - -There is still one more thing to do before you can copy images to the _/photos_ directory. Notice how, when you did `ls -l /` above, permissions for that folder came back as _drwxr-xr-x_. - -If you read [the article I recommended at the beginning of this post][3], you'll know that the first _d_ indicates that the entry in the file system is a directory, and then you have three sets of three characters ( _rwx_ , _r-x_ , _r-x_ ) that indicate the permissions for the user owner ( _rwx_ ) of the directory, then the group owner ( _r-x_ ), and finally the rest of the users ( _r-x_ ). This means that the only person who has write permissions so far, that is, the only person who can copy or create files in the _/photos_ directory, is the _root_ user. - -But [that article I mentioned also tells you how to change the permissions for a directory or file][3]: -``` -sudo chmod g+w /photos - -``` - -Running `ls -l /` after that will give you _/photos_ permissions as _drwxrwxr-x_ which is what you want: group members can now write into the directory. - -Now you can try and copy an image or, indeed, any other file to the directory and it should go through without a problem: -``` -cp image.jpg /photos - -``` - -The _guest_ user will also be able to read and write from the directory. They will also be able to read and write to it, and even move or delete files created by other users within the shared directory. - -### Conclusion - -The permissions and privileges system in Linux has been honed over decades. inherited as it is from the old Unix systems of yore. As such, it works very well and is well thought out. Becoming familiar with it is essential for any Linux sysadmin. In fact, you can't do much admining at all unless you understand it. But, it's not that hard. - -Next time, we'll be dive into files and see the different ways of creating, manipulating, and destroying them in creative ways. Always fun, that last one. - -See you then! - -Learn more about Linux through the free ["Introduction to Linux" ][4]course from The Linux Foundation and edX. - --------------------------------------------------------------------------------- - -via: https://www.linux.com/blog/learn/intro-to-linux/2018/7/users-groups-and-other-linux-beasts-part-2 - -作者：[Paul Brown][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://www.linux.com/users/bro66 -[1]:https://www.linux.com/blog/learn/2018/5/manipulating-directories-linux -[2]:https://www.linux.com/learn/intro-to-linux/2018/7/users-groups-and-other-linux-beasts -[3]:https://www.linux.com/learn/understanding-linux-file-permissions -[4]:https://training.linuxfoundation.org/linux-courses/system-administration-training/introduction-to-linux diff --git a/sources/tech/20180725 Build an interactive CLI with Node.js.md b/sources/tech/20180725 Build an interactive CLI with Node.js.md deleted file mode 100644 index f240e51efd..0000000000 --- a/sources/tech/20180725 Build an interactive CLI with Node.js.md +++ /dev/null @@ -1,533 +0,0 @@ -translating by Flowsnow - -Build an interactive CLI with Node.js -====== - - - -Node.js can be very useful when it comes to building command-line interfaces (CLIs). In this post, I'll teach you how to use [Node.js][1] to build a CLI that asks some questions and creates a file based on the answers. - -### Get started - -Let's start by creating a brand new [npm][2] package. (Npm is the JavaScript package manager.) -``` -mkdir my-script - -cd my-script - -npm init - -``` - -Npm will ask some questions. After that, we need to install some packages. -``` -npm install --save chalk figlet inquirer shelljs - -``` - -Here's what these packages do: - - * **Chalk:** Terminal string styling done right - * **Figlet:** A program for making large letters out of ordinary text - * **Inquirer:** A collection of common interactive command-line user interfaces - * **ShellJS:** Portable Unix shell commands for Node.js - - - -### Make an index.js file - -Now we'll create an `index.js` file with the following content: -``` -#!/usr/bin/env node - - - -const inquirer = require("inquirer"); - -const chalk = require("chalk"); - -const figlet = require("figlet"); - -const shell = require("shelljs"); - -``` - -### Plan the CLI - -It's always good to plan what a CLI needs to do before writing any code. This CLI will do just one thing: **create a file**. - -The CLI will ask two questions—what is the filename and what is the extension?—then create the file, and show a success message with the created file path. -``` -// index.js - - - -const run = async () => { - - // show script introduction - - // ask questions - - // create the file - - // show success message - -}; - - - -run(); - -``` - -The first function is the script introduction. Let's use `chalk` and `figlet` to get the job done. -``` -const init = () => { - - console.log( - - chalk.green( - - figlet.textSync("Node JS CLI", { - - font: "Ghost", - - horizontalLayout: "default", - - verticalLayout: "default" - - }) - - ) - - ); - -} - - - -const run = async () => { - - // show script introduction - - init(); - - - - // ask questions - - // create the file - - // show success message - -}; - - - -run(); - -``` - -Second, we'll write a function that asks the questions. -``` -const askQuestions = () => { - - const questions = [ - - { - - name: "FILENAME", - - type: "input", - - message: "What is the name of the file without extension?" - - }, - - { - - type: "list", - - name: "EXTENSION", - - message: "What is the file extension?", - - choices: [".rb", ".js", ".php", ".css"], - - filter: function(val) { - - return val.split(".")[1]; - - } - - } - - ]; - - return inquirer.prompt(questions); - -}; - - - -// ... - - - -const run = async () => { - - // show script introduction - - init(); - - - - // ask questions - - const answers = await askQuestions(); - - const { FILENAME, EXTENSION } = answers; - - - - // create the file - - // show success message - -}; - -``` - -Notice the constants FILENAME and EXTENSIONS that came from `inquirer`. - -The next step will create the file. -``` -const createFile = (filename, extension) => { - - const filePath = `${process.cwd()}/${filename}.${extension}` - - shell.touch(filePath); - - return filePath; - -}; - - - -// ... - - - -const run = async () => { - - // show script introduction - - init(); - - - - // ask questions - - const answers = await askQuestions(); - - const { FILENAME, EXTENSION } = answers; - - - - // create the file - - const filePath = createFile(FILENAME, EXTENSION); - - - - // show success message - -}; - -``` - -And last but not least, we'll show the success message along with the file path. -``` -const success = (filepath) => { - - console.log( - - chalk.white.bgGreen.bold(`Done! File created at ${filepath}`) - - ); - -}; - - - -// ... - - - -const run = async () => { - - // show script introduction - - init(); - - - - // ask questions - - const answers = await askQuestions(); - - const { FILENAME, EXTENSION } = answers; - - - - // create the file - - const filePath = createFile(FILENAME, EXTENSION); - - - - // show success message - - success(filePath); - -}; - -``` - -Let's test the script by running `node index.js`. Here's what we get: - -### The full code - -Here is the final code: -``` -#!/usr/bin/env node - - - -const inquirer = require("inquirer"); - -const chalk = require("chalk"); - -const figlet = require("figlet"); - -const shell = require("shelljs"); - - - -const init = () => { - - console.log( - - chalk.green( - - figlet.textSync("Node JS CLI", { - - font: "Ghost", - - horizontalLayout: "default", - - verticalLayout: "default" - - }) - - ) - - ); - -}; - - - -const askQuestions = () => { - - const questions = [ - - { - - name: "FILENAME", - - type: "input", - - message: "What is the name of the file without extension?" - - }, - - { - - type: "list", - - name: "EXTENSION", - - message: "What is the file extension?", - - choices: [".rb", ".js", ".php", ".css"], - - filter: function(val) { - - return val.split(".")[1]; - - } - - } - - ]; - - return inquirer.prompt(questions); - -}; - - - -const createFile = (filename, extension) => { - - const filePath = `${process.cwd()}/${filename}.${extension}` - - shell.touch(filePath); - - return filePath; - -}; - - - -const success = filepath => { - - console.log( - - chalk.white.bgGreen.bold(`Done! File created at ${filepath}`) - - ); - -}; - - - -const run = async () => { - - // show script introduction - - init(); - - - - // ask questions - - const answers = await askQuestions(); - - const { FILENAME, EXTENSION } = answers; - - - - // create the file - - const filePath = createFile(FILENAME, EXTENSION); - - - - // show success message - - success(filePath); - -}; - - - -run(); - -``` - -### Use the script anywhere - -To execute this script anywhere, add a `bin` section in your `package.json` file and run `npm link`. -``` -{ - - "name": "creator", - - "version": "1.0.0", - - "description": "", - - "main": "index.js", - - "scripts": { - - "test": "echo \"Error: no test specified\" && exit 1", - - "start": "node index.js" - - }, - - "author": "", - - "license": "ISC", - - "dependencies": { - - "chalk": "^2.4.1", - - "figlet": "^1.2.0", - - "inquirer": "^6.0.0", - - "shelljs": "^0.8.2" - - }, - - "bin": { - - "creator": "./index.js" - - } - -} - -``` - -Running `npm link` makes this script available anywhere. - -That's what happens when you run this command: -``` -/usr/bin/creator -> /usr/lib/node_modules/creator/index.js - -/usr/lib/node_modules/creator -> /home/hugo/code/creator - -``` - -It links the `index.js` file as an executable. This is only possible because of the first line of the CLI script: `#!/usr/bin/env node`. - -Now we can run this script by calling: -``` -$ creator - -``` - -### Wrapping up - -As you can see, Node.js makes it very easy to build nice command-line tools! If you want to go even further, check this other packages: - - * [meow][3] – a simple command-line helper - * [yargs][4] – a command-line opt-string parser - * [pkg][5] – package your Node.js project into an executable - - - -Tell us about your experience building a CLI in the comments. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/7/node-js-interactive-cli - -作者：[Hugo Dias][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://opensource.com/users/hugodias -[1]:https://nodejs.org/en/ -[2]:https://www.npmjs.com/ -[3]:https://github.com/sindresorhus/meow -[4]:https://github.com/yargs/yargs -[5]:https://github.com/zeit/pkg diff --git a/sources/tech/20180727 How to analyze your system with perf and Python.md b/sources/tech/20180727 How to analyze your system with perf and Python.md index 4573ed1ee0..c1be98cc0e 100644 --- a/sources/tech/20180727 How to analyze your system with perf and Python.md +++ b/sources/tech/20180727 How to analyze your system with perf and Python.md @@ -1,7 +1,3 @@ -**translating by [erlinux](https://github.com/erlinux)** -**PROJECT MANAGEMENT TOOL called [gn2.sh](https://github.com/lctt/lctt-cli)** - - How to analyze your system with perf and Python ====== diff --git a/sources/tech/20180806 GPaste Is A Great Clipboard Manager For Gnome Shell.md b/sources/tech/20180806 GPaste Is A Great Clipboard Manager For Gnome Shell.md deleted file mode 100644 index c3b2d2b77e..0000000000 --- a/sources/tech/20180806 GPaste Is A Great Clipboard Manager For Gnome Shell.md +++ /dev/null @@ -1,96 +0,0 @@ -GPaste Is A Great Clipboard Manager For Gnome Shell -====== -**[GPaste][1] is a clipboard management system that consists of a library, daemon, and interfaces for the command line and Gnome (using a native Gnome Shell extension).** - -A clipboard manager allows keeping track of what you're copying and pasting, providing access to previously copied items. GPaste, with its native Gnome Shell extension, makes the perfect addition for those looking for a Gnome clipboard manager. - -[![GPaste Gnome Shell extension Ubuntu 18.04][2]][3] -GPaste Gnome Shell extension -**Using GPaste in Gnome, you get a configurable, searchable clipboard history, available with a click on the top panel. GPaste remembers not only the text you copy, but also file paths and images** (the latter needs to be enabled from its settings as it's disabled by default). - -What's more, GPaste can detect growing lines, meaning it can detect when a new text copy is an extension of another and replaces it if it's true, useful for keeping your clipboard clean. - -From the extension menu you can pause GPaste from tracking the clipboard, and remove items from the clipboard history or the whole history. You'll also find a button that launches the GPaste user interface window. - -**If you prefer to use the keyboard, you can use a key shortcut to open the GPaste history from the top bar** (`Ctrl + Alt + H`), **or open the full GPaste GUI** (`Ctrl + Alt + G`). - -The tool also incorporates keyboard shortcuts to (can be changed): - - * delete the active item from history: `Ctrl + Alt + V` - - * **mark the active item as being a password (which obfuscates the clipboard entry in GPaste):** `Ctrl + Alt + S` - - * sync the clipboard to the primary selection: `Ctrl + Alt + O` - - * sync the primary selection to the clipboard: `Ctrl + Alt + P` - - * upload the active item to a pastebin service: `Ctrl + Alt + U` - -[![][4]][5] -GPaste GUI - -The GPaste interface window provides access to the clipboard history (with options to clear, edit or upload items), which can be searched, an option to pause GPaste from tracking the clipboard, restart the GPaste daemon, backup current clipboard history, as well as to its settings. - -[![][6]][7] -GPaste GUI - -From the GPaste UI you can change settings like: - - * Enable or disable the Gnome Shell extension - * Sync the daemon state with the extension's one - * Primary selection affects history - * Synchronize clipboard with primary selection - * Image support - * Trim items - * Detect growing lines - * Save history - * History settings like max history size, memory usage, max text item length, and more - * Keyboard shortcuts - - - -### Download GPaste - -[Download GPaste](https://github.com/Keruspe/GPaste) - -The Gpaste project page does not link to any GPaste binaries, and only source installation instructions. Users running Linux distributions other than Debian or Ubuntu (for which you'll find GPaste installation instructions below) can search their distro repositories for GPaste. - -Do not confuse GPaste with the GPaste Integration extension posted on the Gnome Shell extension website. That is a Gnome Shell extension that uses GPaste daemon, which is no longer maintained. The native Gnome Shell extension built into GPaste is still maintained. - -#### Install GPaste in Ubuntu (18.04, 16.04) or Debian (Jessie and newer) - -**For Debian, GPaste is available for Jessie and newer, while for Ubuntu, GPaste is in the repositories for 16.04 and newer (so it's available in the Ubuntu 18.04 Bionic Beaver).** - -**You can install GPaste (the daemon and the Gnome Shell extension) in Debian or Ubuntu using this command:** -``` -sudo apt install gnome-shell-extensions-gpaste gpaste - -``` - -After the installation completes, restart Gnome Shell by pressing `Alt + F2` and typing `r` , then pressing the `Enter` key. The GPaste Gnome Shell extension should now be enabled and its icon should show up on the top Gnome Shell panel. If it's not, use Gnome Tweaks (Gnome Tweak Tool) to enable the extension. - -**The GPaste 3.28.0 package from[Debian][8] and [Ubuntu][9] has a bug that makes it crash if the image support option is enabled, so do not enable this feature for now.** This was marked as - - --------------------------------------------------------------------------------- - -via: https://www.linuxuprising.com/2018/08/gpaste-is-great-clipboard-manager-for.html - -作者：[Logix][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://plus.google.com/118280394805678839070 -[1]:https://github.com/Keruspe/GPaste -[2]:https://2.bp.blogspot.com/-2ndArDBcrwY/W2gyhMc1kEI/AAAAAAAABS0/ZAe_onuGCacMblF733QGBX3XqyZd--WuACLcBGAs/s400/gpaste-gnome-shell-extension-ubuntu1804.png (Gpaste Gnome Shell) -[3]:https://2.bp.blogspot.com/-2ndArDBcrwY/W2gyhMc1kEI/AAAAAAAABS0/ZAe_onuGCacMblF733QGBX3XqyZd--WuACLcBGAs/s1600/gpaste-gnome-shell-extension-ubuntu1804.png -[4]:https://2.bp.blogspot.com/-7FBRsZJvYek/W2gyvzmeRxI/AAAAAAAABS4/LhokMFSn8_kZndrNB-BTP4W3e9IUuz9BgCLcBGAs/s640/gpaste-gui_1.png -[5]:https://2.bp.blogspot.com/-7FBRsZJvYek/W2gyvzmeRxI/AAAAAAAABS4/LhokMFSn8_kZndrNB-BTP4W3e9IUuz9BgCLcBGAs/s1600/gpaste-gui_1.png -[6]:https://4.bp.blogspot.com/-047ShYc6RrQ/W2gyz5FCf_I/AAAAAAAABTA/-o6jaWzwNpsSjG0QRwRJ5Xurq_A6dQ0sQCLcBGAs/s640/gpaste-gui_2.png -[7]:https://4.bp.blogspot.com/-047ShYc6RrQ/W2gyz5FCf_I/AAAAAAAABTA/-o6jaWzwNpsSjG0QRwRJ5Xurq_A6dQ0sQCLcBGAs/s1600/gpaste-gui_2.png -[8]:https://packages.debian.org/buster/gpaste -[9]:https://launchpad.net/ubuntu/+source/gpaste -[10]:https://www.imagination-land.org/posts/2018-04-13-gpaste-3.28.2-released.html diff --git a/sources/tech/20180807 5 reasons the i3 window manager makes Linux better.md b/sources/tech/20180807 5 reasons the i3 window manager makes Linux better.md deleted file mode 100644 index 8ad6a4ac7d..0000000000 --- a/sources/tech/20180807 5 reasons the i3 window manager makes Linux better.md +++ /dev/null @@ -1,111 +0,0 @@ -5 reasons the i3 window manager makes Linux better -====== - - - -One of the nicest things about Linux (and open source software in general) is the freedom to choose among different alternatives to address our needs. - -I've been using Linux for a long time, but I was never entirely happy with the desktop environment options available. Until last year, [Xfce][1] was the closest to what I consider a good compromise between features and performance. Then I found [i3][2], an amazing piece of software that changed my life. - -I3 is a tiling window manager. The goal of a window manager is to control the appearance and placement of windows in a windowing system. Window managers are often used as part a full-featured desktop environment (such as GNOME or Xfce), but some can also be used as standalone applications. - -A tiling window manager automatically arranges the windows to occupy the whole screen in a non-overlapping way. Other popular tiling window managers include [wmii][3] and [xmonad][4]. - -![i3 tiled window manager screenshot][6] - -Screenshot of i3 with three tiled windows - -Following are the top five reasons I use the i3 window manager and recommend it for a better Linux desktop experience. - -### 1\. Minimalism - -I3 is fast. It is neither bloated nor fancy. It is designed to be simple and efficient. As a developer, I value these features, as I can use the extra capacity to power my favorite development tools or test stuff locally using containers or virtual machines. - -In addition, i3 is a window manager and, unlike full-featured desktop environments, it does not dictate the applications you should use. Do you want to use Thunar from Xfce as your file manager? GNOME's gedit to edit text? I3 does not care. Pick the tools that make the most sense for your workflow, and i3 will manage them all in the same way. - -### 2\. Screen real estate - -As a tiling window manager, i3 will automatically "tile" or position the windows in a non-overlapping way, similar to laying tiles on a wall. Since you don't need to worry about window positioning, i3 generally makes better use of your screen real estate. It also allows you to get to what you need faster. - -There are many useful cases for this. For example, system administrators can open several terminals to monitor or work on different remote systems simultaneously; and developers can use their favorite IDE or editor and a few terminals to test their programs. - -In addition, i3 is flexible. If you need more space for a particular window, enable full-screen mode or switch to a different layout, such as stacked or tabbed. - -### 3\. Keyboard-driven workflow - -I3 makes extensive use of keyboard shortcuts to control different aspects of your environment. These include opening the terminal and other programs, resizing and positioning windows, changing layouts, and even exiting i3. When you start using i3, you need to memorize a few of those shortcuts to get around and, with time, you'll use more of them. - -The main benefit is that you don't often need to switch contexts from the keyboard to the mouse. With practice, it means you'll improve the speed and efficiency of your workflow. - -For example, to open a new terminal, press ` + `. Since the windows are automatically positioned, you can start typing your commands right away. Combine that with a nice terminal-driven text editor (e.g., Vim) and a keyboard-focused browser for a fully keyboard-driven workflow. - -In i3, you can define shortcuts for everything. Here are some examples: - - * Open terminal - * Open browser - * Change layouts - * Resize windows - * Control music player - * Switch workspaces - - - -Now that I am used to this workflow, I can't see myself going back to a regular desktop environment. - -### 4\. Flexibility - -I3 strives to be minimal and use few system resources, but that does not mean it can't be pretty. I3 is flexible and can be customized in several ways to improve the visual experience. Because i3 is a window manager, it doesn't provide tools to enable customizations; you need external tools for that. Some examples: - - * Use `feh` to define a background picture for your desktop. - * Use a compositor manager such as `compton` to enable effects like window fading and transparency. - * Use `dmenu` or `rofi` to enable customizable menus that can be launched from a keyboard shortcut. - * Use `dunst` for desktop notifications. - - - -I3 is fully configurable, and you can control every aspect of it by updating the default configuration file. From changing all keyboard shortcuts, to redefining the name of the workspaces, to modifying the status bar, you can make i3 behave in any way that makes the most sense for your needs. - -![i3 with rofi menu and dunst desktop notifications][8] - -i3 with `rofi` menu and `dunst` desktop notifications - -Finally, for more advanced users, i3 provides a full interprocess communication ([IPC][9]) interface that allows you to use your favorite language to develop scripts or programs for even more customization options. - -### 5\. Workspaces - -In i3, a workspace is an easy way to group windows. You can group them in different ways according to your workflow. For example, you can put the browser on one workspace, the terminal on another, an email client on a third, etc. You can even change i3's configuration to always assign specific applications to their own workspaces. - -Switching workspaces is quick and easy. As usual in i3, do it with a keyboard shortcut. Press ` +num` to switch to workspace `num`. If you get into the habit of always assigning applications/groups of windows to the same workspace, you can quickly switch between them, which makes workspaces a very useful feature. - -In addition, you can use workspaces to control multi-monitor setups, where each monitor gets an initial workspace. If you switch to that workspace, you switch to that monitor—without moving your hand off the keyboard. - -Finally, there is another, special type of workspace in i3: the scratchpad. It is an invisible workspace that shows up in the middle of the other workspaces by pressing a shortcut. This is a convenient way to access windows or programs that you frequently use, such as an email client or your music player. - -### Give it a try - -If you value simplicity and efficiency and are not afraid of working with the keyboard, i3 is the window manager for you. Some say it is for advanced users, but that is not necessarily the case. You need to learn a few basic shortcuts to get around at the beginning, but they'll soon feel natural and you'll start using them without thinking. - -This article just scratches the surface of what i3 can do. For more details, consult [i3's documentation][10]. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/8/i3-tiling-window-manager - -作者：[Ricardo Gerardi][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://opensource.com/users/rgerardi -[1]:https://xfce.org/ -[2]:https://i3wm.org/ -[3]:https://code.google.com/archive/p/wmii/ -[4]:https://xmonad.org/ -[5]:/file/406476 -[6]:https://opensource.com/sites/default/files/uploads/i3_screenshot.png (i3 tiled window manager screenshot) -[7]:/file/405161 -[8]:https://opensource.com/sites/default/files/uploads/rofi_dunst.png (i3 with rofi menu and dunst desktop notifications) -[9]:https://i3wm.org/docs/ipc.html -[10]:https://i3wm.org/docs/userguide.html diff --git a/sources/tech/20180809 Perform robust unit tests with PyHamcrest.md b/sources/tech/20180809 Perform robust unit tests with PyHamcrest.md deleted file mode 100644 index 1c7d7e9226..0000000000 --- a/sources/tech/20180809 Perform robust unit tests with PyHamcrest.md +++ /dev/null @@ -1,176 +0,0 @@ -Perform robust unit tests with PyHamcrest -====== - - - -At the base of the [testing pyramid][1] are unit tests. Unit tests test one unit of code at a time—usually one function or method. - -Often, a single unit test is designed to test one particular flow through a function, or a specific branch choice. This enables easy mapping of a unit test that fails and the bug that made it fail. - -Ideally, unit tests use few or no external resources, isolating them and making them faster. - -_Good_ tests increase developer productivity by catching bugs early and making testing faster. _Bad_ tests decrease developer productivity. - -Unit test suites help maintain high-quality products by signaling problems early in the development process. An effective unit test catches bugs before the code has left the developer machine, or at least in a continuous integration environment on a dedicated branch. This marks the difference between good and bad unit tests:tests increase developer productivity by catching bugs early and making testing faster.tests decrease developer productivity. - -Productivity usually decreases when testing _incidental features_. The test fails when the code changes, even if it is still correct. This happens because the output is different, but in a way that is not part of the function's contract. - -A good unit test, therefore, is one that helps enforce the contract to which the function is committed. - -If a unit test breaks, the contract is violated and should be either explicitly amended (by changing the documentation and tests), or fixed (by fixing the code and leaving the tests as is). - -While limiting tests to enforce only the public contract is a complicated skill to learn, there are tools that can help. - -One of these tools is [Hamcrest][2], a framework for writing assertions. Originally invented for Java-based unit tests, today the Hamcrest framework supports several languages, including [Python][3]. - -Hamcrest is designed to make test assertions easier to write and more precise. -``` -def add(a, b): - - return a + b - - - -from hamcrest import assert_that, equal_to - - - -def test_add(): - - assert_that(add(2, 2), equal_to(4)) - -``` - -This is a simple assertion, for simple functionality. What if we wanted to assert something more complicated? -``` -def test_set_removal(): - - my_set = {1, 2, 3, 4} - - my_set.remove(3) - - assert_that(my_set, contains_inanyorder([1, 2, 4])) - - assert_that(my_set, is_not(has_item(3))) - -``` - -Note that we can succinctly assert that the result has `1`, `2`, and `4` in any order since sets do not guarantee order. - -We also easily negate assertions with `is_not`. This helps us write _precise assertions_ , which allow us to limit ourselves to enforcing public contracts of functions. - -Sometimes, however, none of the built-in functionality is _precisely_ what we need. In those cases, Hamcrest allows us to write our own matchers. - -Imagine the following function: -``` -def scale_one(a, b): - - scale = random.randint(0, 5) - - pick = random.choice([a,b]) - - return scale * pick - -``` - -We can confidently assert that the result divides into at least one of the inputs evenly. - -A matcher inherits from `hamcrest.core.base_matcher.BaseMatcher`, and overrides two methods: -``` -class DivisibleBy(hamcrest.core.base_matcher.BaseMatcher): - - - - def __init__(self, factor): - - self.factor = factor - - - - def _matches(self, item): - - return (item % self.factor) == 0 - - - - def describe_to(self, description): - - description.append_text('number divisible by') - - description.append_text(repr(self.factor)) - -``` - -Writing high-quality `describe_to` methods is important, since this is part of the message that will show up if the test fails. -``` -def divisible_by(num): - - return DivisibleBy(num) - -``` - -By convention, we wrap matchers in a function. Sometimes this gives us a chance to further process the inputs, but in this case, no further processing is needed. -``` -def test_scale(): - - result = scale_one(3, 7) - - assert_that(result, - - any_of(divisible_by(3), - - divisible_by(7))) - -``` - -Note that we combined our `divisible_by` matcher with the built-in `any_of` matcher to ensure that we test only what the contract commits to. - -While editing this article, I heard a rumor that the name "Hamcrest" was chosen as an anagram for "matches". Hrm... -``` ->>> assert_that("matches", contains_inanyorder(*"hamcrest") - -Traceback (most recent call last): - - File " ", line 1, in - - File "/home/moshez/src/devops-python/build/devops/lib/python3.6/site-packages/hamcrest/core/assert_that.py", line 43, in assert_that - - _assert_match(actual=arg1, matcher=arg2, reason=arg3) - - File "/home/moshez/src/devops-python/build/devops/lib/python3.6/site-packages/hamcrest/core/assert_that.py", line 57, in _assert_match - - raise AssertionError(description) - -AssertionError: - -Expected: a sequence over ['h', 'a', 'm', 'c', 'r', 'e', 's', 't'] in any order - - but: no item matches: 'r' in ['m', 'a', 't', 'c', 'h', 'e', 's'] - -``` - -Researching more, I found the source of the rumor: It is an anagram for "matchers". -``` ->>> assert_that("matchers", contains_inanyorder(*"hamcrest")) - ->>> - -``` - -If you are not yet writing unit tests for your Python code, now is a good time to start. If you are writing unit tests for your Python code, using Hamcrest will allow you to make your assertion _precise_ —neither more nor less than what you intend to test. This will lead to fewer false positives when modifying code and less time spent modifying tests for working code. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/8/robust-unit-tests-hamcrest - -作者：[Moshe Zadka][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://opensource.com/users/moshez -[1]:https://martinfowler.com/bliki/TestPyramid.html -[2]:http://hamcrest.org/ -[3]:https://www.python.org/ diff --git a/sources/tech/20180814 5 open source strategy and simulation games for Linux.md b/sources/tech/20180814 5 open source strategy and simulation games for Linux.md deleted file mode 100644 index 1f7e94c22f..0000000000 --- a/sources/tech/20180814 5 open source strategy and simulation games for Linux.md +++ /dev/null @@ -1,111 +0,0 @@ -5 open source strategy and simulation games for Linux -====== - - - -Gaming has traditionally been one of Linux's weak points. That has changed somewhat in recent years thanks to Steam, GOG, and other efforts to bring commercial games to multiple operating systems, but those games are often not open source. Sure, the games can be played on an open source operating system, but that is not good enough for an open source purist. - -So, can someone who only uses free and open source software find games that are polished enough to present a solid gaming experience without compromising their open source ideals? Absolutely. While open source games are unlikely ever to rival some of the AAA commercial games developed with massive budgets, there are plenty of open source games, in many genres, that are fun to play and can be installed from the repositories of most major Linux distributions. Even if a particular game is not packaged for a particular distribution, it is usually easy to download the game from the project's website to install and play it. - -This article looks at strategy and simulation games. I have already written about [arcade-style games][1], [board & card games][2], [puzzle games][3], [racing & flying games][4], and [role-playing games][5]. - -### Freeciv - - - -[Freeciv][6] is an open source version of the [Civilization series][7] of computer games. Gameplay is most similar to the earlier games in the Civilization series, and Freeciv even has options to use Civilization 1 and Civilization 2 rule sets. Freeciv involves building cities, exploring the world map, developing technologies, and competing with other civilizations trying to do the same. Victory conditions include defeating all the other civilizations, developing a space colony, or hitting deadline if neither of the first two conditions are met. The game can be played against AI opponents or other human players. Different tile-sets are available to change the look of the game's map. - -To install Freeciv, run the following command: - - * On Fedora: `dnf install freeciv` - * On Debian/Ubuntu: `apt install freeciv` - - - -### MegaGlest - - - -[MegaGlest][8] is an open source real-time strategy game in the style of Blizzard Entertainment's [Warcraft][9] and [StarCraft][10] games. Players control one of several different factions, building structures and recruiting units to explore the map and battle their opponents. At the beginning of the match, a player can build only the most basic buildings and recruit the weakest units. To build and recruit better things, players must work their way up their factions technology tree by building structures and recruiting units that unlock more advanced options. Combat units will attack when enemy units come into range, but for optimal strategy, it is best to manage the battle directly by controlling the units. Simultaneously managing the construction of new structures, recruiting new units, and managing battles can be a challenge, but that is the point of a real-time strategy game. MegaGlest provides a nice variety of factions, so there are plenty of reasons to try new and different strategies. - -To install MegaGlest, run the following command: - - * On Fedora: `dnf install megaglest` - * On Debian/Ubuntu: `apt install megaglest` - - - -### OpenTTD - - - -[OpenTTD][11] (see also [our review][12]) is an open source implementation of [Transport Tycoon Deluxe][13]. The object of the game is to create a transportation network and earn money, which allows the player to build an even bigger transportation network. The network can include boats, buses, trains, trucks, and planes. By default, gameplay takes place between 1950 and 2050, with players aiming to get the highest performance rating possible before time runs out. The performance rating is based on things like the amount of cargo delivered, the number of vehicles they have, and how much money they earned. - -To install OpenTTD, run the following command: - - * On Fedora: `dnf install openttd` - * On Debian/Ubuntu: `apt install openttd` - - - -### The Battle for Wesnoth - - - -[The Battle for Wesnoth][14] is one of the most polished open source games available. This turn-based strategy game has a fantasy setting. Play takes place on a hexagonal grid, where individual units battle each other for control. Each type of unit has unique strengths and weaknesses, which requires players to plan their attacks accordingly. There are many different campaigns available for The Battle for Wesnoth, each with different objectives and storylines. The Battle for Wesnoth also comes with a map editor for players interested in creating their own maps or campaigns. - -To install The Battle for Wesnoth, run the following command: - - * On Fedora: `dnf install wesnoth` - * On Debian/Ubuntu: `apt install wesnoth` - - - -### UFO: Alien Invasion - - - -[UFO: Alien Invasion][15] is an open source tactical strategy game inspired by the [X-COM series][20]. There are two distinct gameplay modes: geoscape and tactical. In geoscape mode, the player takes control of the big picture and deals with managing their bases, researching new technologies, and controlling overall strategy. In tactical mode, the player controls a squad of soldiers and directly confronts the alien invaders in a turn-based battle. Both modes provide different gameplay styles, but both require complex strategy and tactics. - -To install UFO: Alien Invasion, run the following command: - - * On Debian/Ubuntu: `apt install ufoai` - - - -Unfortunately, UFO: Alien Invasion is not packaged for Fedora. - -Did I miss one of your favorite open source strategy or simulation games? Share it in the comments below. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/8/strategy-simulation-games-linux - -作者：[Joshua Allen Holm][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://opensource.com/users/holmja -[1]:https://opensource.com/article/18/1/arcade-games-linux -[2]:https://opensource.com/article/18/3/card-board-games-linux -[3]:https://opensource.com/article/18/6/puzzle-games-linux -[4]:https://opensource.com/article/18/7/racing-flying-games-linux -[5]:https://opensource.com/article/18/8/role-playing-games-linux -[6]:http://www.freeciv.org/ -[7]:https://en.wikipedia.org/wiki/Civilization_(series) -[8]:https://megaglest.org/ -[9]:https://en.wikipedia.org/wiki/Warcraft -[10]:https://en.wikipedia.org/wiki/StarCraft -[11]:https://www.openttd.org/ -[12]:https://opensource.com/life/15/7/linux-game-review-openttd -[13]:https://en.wikipedia.org/wiki/Transport_Tycoon#Transport_Tycoon_Deluxe -[14]:https://www.wesnoth.org/ -[15]:https://ufoai.org/ -[16]:https://opensource.com/downloads/cheat-sheets?intcmp=7016000000127cYAAQ -[17]:https://opensource.com/alternatives?intcmp=7016000000127cYAAQ -[18]:https://opensource.com/tags/linux?intcmp=7016000000127cYAAQ -[19]:https://developers.redhat.com/cheat-sheets/advanced-linux-commands/?intcmp=7016000000127cYAAQ -[20]:https://en.wikipedia.org/wiki/X-COM diff --git a/sources/tech/20180814 HTTP request routing and validation with gorilla-mux.md b/sources/tech/20180814 HTTP request routing and validation with gorilla-mux.md deleted file mode 100644 index 410f692ad9..0000000000 --- a/sources/tech/20180814 HTTP request routing and validation with gorilla-mux.md +++ /dev/null @@ -1,674 +0,0 @@ -HTTP request routing and validation with gorilla/mux -====== - - - -The Go networking library includes the `http.ServeMux` structure type, which supports HTTP request multiplexing (routing): A web server routes an HTTP request for a hosted resource, with a URI such as /sales4today, to a code handler; the handler performs the appropriate logic before sending an HTTP response, typically an HTML page. Here’s a sketch of the architecture: -``` - +------------+ +--------+ +---------+ -HTTP request---->| web server |---->| router |---->| handler | - +------------+ +--------+ +---------+ -``` - -In a call to the `ListenAndServe` method to start an HTTP server -``` -http.ListenAndServe(":8888", nil) // args: port & router -``` - -a second argument of `nil` means that the `DefaultServeMux` is used for request routing. - -The `gorilla/mux` package has a `mux.Router` type as an alternative to either the `DefaultServeMux` or a customized request multiplexer. In the `ListenAndServe` call, a `mux.Router` instance would replace `nil` as the second argument. What makes the `mux.Router` so appealing is best shown through a code example: - -### 1\. A sample crud web app - -The crud web application (see below) supports the four CRUD (Create Read Update Delete) operations, which match four HTTP request methods: POST, GET, PUT, and DELETE, respectively. In the crud app, the hosted resource is a list of cliche pairs, each a cliche and a conflicting cliche such as this pair: -``` -Out of sight, out of mind. Absence makes the heart grow fonder. - -``` - -New cliche pairs can be added, and existing ones can be edited or deleted. - -**The crud web app** -``` -package main - -import ( - "gorilla/mux" - "net/http" - "fmt" - "strconv" -) - -const GETALL string = "GETALL" -const GETONE string = "GETONE" -const POST string = "POST" -const PUT string = "PUT" -const DELETE string = "DELETE" - -type clichePair struct { - Id int - Cliche string - Counter string -} - -// Message sent to goroutine that accesses the requested resource. -type crudRequest struct { - verb string - cp *clichePair - id int - cliche string - counter string - confirm chan string -} - -var clichesList = []*clichePair{} -var masterId = 1 -var crudRequests chan *crudRequest - -// GET / -// GET /cliches -func ClichesAll(res http.ResponseWriter, req *http.Request) { - cr := &crudRequest{verb: GETALL, confirm: make(chan string)} - completeRequest(cr, res, "read all") -} - -// GET /cliches/id -func ClichesOne(res http.ResponseWriter, req *http.Request) { - id := getIdFromRequest(req) - cr := &crudRequest{verb: GETONE, id: id, confirm: make(chan string)} - completeRequest(cr, res, "read one") -} - -// POST /cliches - -func ClichesCreate(res http.ResponseWriter, req *http.Request) { - - cliche, counter := getDataFromRequest(req) - - cp := new(clichePair) - - cp.Cliche = cliche - - cp.Counter = counter - - cr := &crudRequest{verb: POST, cp: cp, confirm: make(chan string)} - - completeRequest(cr, res, "create") - -} - - - -// PUT /cliches/id - -func ClichesEdit(res http.ResponseWriter, req *http.Request) { - - id := getIdFromRequest(req) - - cliche, counter := getDataFromRequest(req) - - cr := &crudRequest{verb: PUT, id: id, cliche: cliche, counter: counter, confirm: make(chan string)} - - completeRequest(cr, res, "edit") - -} - - - -// DELETE /cliches/id - -func ClichesDelete(res http.ResponseWriter, req *http.Request) { - - id := getIdFromRequest(req) - - cr := &crudRequest{verb: DELETE, id: id, confirm: make(chan string)} - - completeRequest(cr, res, "delete") - -} - - - -func completeRequest(cr *crudRequest, res http.ResponseWriter, logMsg string) { - - crudRequests<-cr - - msg := <-cr.confirm - - res.Write([]byte(msg)) - - logIt(logMsg) - -} - - - -func main() { - - populateClichesList() - - - - // From now on, this gorountine alone accesses the clichesList. - - crudRequests = make(chan *crudRequest, 8) - - go func() { // resource manager - - for { - - select { - - case req := <-crudRequests: - - if req.verb == GETALL { - - req.confirm<-readAll() - - } else if req.verb == GETONE { - - req.confirm<-readOne(req.id) - - } else if req.verb == POST { - - req.confirm<-addPair(req.cp) - - } else if req.verb == PUT { - - req.confirm<-editPair(req.id, req.cliche, req.counter) - - } else if req.verb == DELETE { - - req.confirm<-deletePair(req.id) - - } - - } - - }() - - startServer() - -} - - - -func startServer() { - - router := mux.NewRouter() - - - - // Dispatch map for CRUD operations. - - router.HandleFunc("/", ClichesAll).Methods("GET") - - router.HandleFunc("/cliches", ClichesAll).Methods("GET") - - router.HandleFunc("/cliches/{id:[0-9]+}", ClichesOne).Methods("GET") - - - - router.HandleFunc("/cliches", ClichesCreate).Methods("POST") - - router.HandleFunc("/cliches/{id:[0-9]+}", ClichesEdit).Methods("PUT") - - router.HandleFunc("/cliches/{id:[0-9]+}", ClichesDelete).Methods("DELETE") - - - - http.Handle("/", router) // enable the router - - - - // Start the server. - - port := ":8888" - - fmt.Println("\nListening on port " + port) - - http.ListenAndServe(port, router); // mux.Router now in play - -} - - - -// Return entire list to requester. - -func readAll() string { - - msg := "\n" - - for _, cliche := range clichesList { - - next := strconv.Itoa(cliche.Id) + ": " + cliche.Cliche + " " + cliche.Counter + "\n" - - msg += next - - } - - return msg - -} - - - -// Return specified clichePair to requester. - -func readOne(id int) string { - - msg := "\n" + "Bad Id: " + strconv.Itoa(id) + "\n" - - - - index := findCliche(id) - - if index >= 0 { - - cliche := clichesList[index] - - msg = "\n" + strconv.Itoa(id) + ": " + cliche.Cliche + " " + cliche.Counter + "\n" - - } - - return msg - -} - - - -// Create a new clichePair and add to list - -func addPair(cp *clichePair) string { - - cp.Id = masterId - - masterId++ - - clichesList = append(clichesList, cp) - - return "\nCreated: " + cp.Cliche + " " + cp.Counter + "\n" - -} - - - -// Edit an existing clichePair - -func editPair(id int, cliche string, counter string) string { - - msg := "\n" + "Bad Id: " + strconv.Itoa(id) + "\n" - - index := findCliche(id) - - if index >= 0 { - - clichesList[index].Cliche = cliche - - clichesList[index].Counter = counter - - msg = "\nCliche edited: " + cliche + " " + counter + "\n" - - } - - return msg - -} - - - -// Delete a clichePair - -func deletePair(id int) string { - - idStr := strconv.Itoa(id) - - msg := "\n" + "Bad Id: " + idStr + "\n" - - index := findCliche(id) - - if index >= 0 { - - clichesList = append(clichesList[:index], clichesList[index + 1:]...) - - msg = "\nCliche " + idStr + " deleted\n" - - } - - return msg - -} - - - -//*** utility functions - -func findCliche(id int) int { - - for i := 0; i < len(clichesList); i++ { - - if id == clichesList[i].Id { - - return i; - - } - - } - - return -1 // not found - -} - - - -func getIdFromRequest(req *http.Request) int { - - vars := mux.Vars(req) - - id, _ := strconv.Atoi(vars["id"]) - - return id - -} - - - -func getDataFromRequest(req *http.Request) (string, string) { - - // Extract the user-provided data for the new clichePair - - req.ParseForm() - - form := req.Form - - cliche := form["cliche"][0] // 1st and only member of a list - - counter := form["counter"][0] // ditto - - return cliche, counter - -} - - - -func logIt(msg string) { - - fmt.Println(msg) - -} - - - -func populateClichesList() { - - var cliches = []string { - - "Out of sight, out of mind.", - - "A penny saved is a penny earned.", - - "He who hesitates is lost.", - - } - - var counterCliches = []string { - - "Absence makes the heart grow fonder.", - - "Penny-wise and dollar-foolish.", - - "Look before you leap.", - - } - - - - for i := 0; i < len(cliches); i++ { - - cp := new(clichePair) - - cp.Id = masterId - - masterId++ - - cp.Cliche = cliches[i] - - cp.Counter = counterCliches[i] - - clichesList = append(clichesList, cp) - - } - -} - -``` - -To focus on request routing and validation, the crud app does not use HTML pages as responses to requests. Instead, requests result in plaintext response messages: A list of the cliche pairs is the response to a GET request, confirmation that a new cliche pair has been added to the list is a response to a POST request, and so on. This simplification makes it easy to test the app, in particular, the `gorilla/mux` components, with a command-line utility such as [curl][1]. - -The `gorilla/mux` package can be installed from [GitHub][2]. The crud app runs indefinitely; hence, it should be terminated with a Control-C or equivalent. The code for the crud app, together with a README and sample curl tests, is available on [my website][3]. - -### 2\. Request routing - -The `mux.Router` extends REST-style routing, which gives equal weight to the HTTP method (e.g., GET) and the URI or path at the end of a URL (e.g., /cliches). The URI serves as the noun for the HTTP verb (method). For example, in an HTTP request a startline such as -``` -GET /cliches - -``` - -means get all of the cliche pairs, whereas a startline such as -``` -POST /cliches - -``` - -means create a cliche pair from data in the HTTP body. - -In the crud web app, there are five functions that act as request handlers for five variations of an HTTP request: -``` -ClichesAll(...) # GET: get all of the cliche pairs - -ClichesOne(...) # GET: get a specified cliche pair - -ClichesCreate(...) # POST: create a new cliche pair - -ClichesEdit(...) # PUT: edit an existing cliche pair - -ClichesDelete(...) # DELETE: delete a specified cliche pair - -``` - -Each function takes two arguments: an `http.ResponseWriter` for sending a response back to the requester, and a pointer to an `http.Request`, which encapsulates information from the underlying HTTP request. The `gorilla/mux` package makes it easy to register these request handlers with the web server, and to perform regex-based validation. - -The `startServer` function in the crud app registers the request handlers. Consider this pair of registrations, with `router` as a `mux.Router` instance: -``` -router.HandleFunc("/", ClichesAll).Methods("GET") - -router.HandleFunc("/cliches", ClichesAll).Methods("GET") - -``` - -These statements mean that a GET request for either the single slash / or /cliches should be routed to the `ClichesAll` function, which then handles the request. For example, the curl request (with % as the command-line prompt) -``` -% curl --request GET localhost:8888/ - -``` - -produces this response: -``` -1: Out of sight, out of mind. Absence makes the heart grow fonder. - -2: A penny saved is a penny earned. Penny-wise and dollar-foolish. - -3: He who hesitates is lost. Look before you leap. - -``` - -The three cliche pairs are the initial data in the crud app. - -In this pair of registration statements -``` -router.HandleFunc("/cliches", ClichesAll).Methods("GET") - -router.HandleFunc("/cliches", ClichesCreate).Methods("POST") - -``` - -the URI is the same (/cliches) but the verbs differ: GET in the first case, and POST in the second. This registration exemplifies REST-style routing because the difference in the verbs alone suffices to dispatch the requests to two different handlers. - -More than one HTTP method is allowed in a registration, although this strains the spirit of REST-style routing: -``` -router.HandleFunc("/cliches", DoItAll).Methods("POST", "GET") - -``` - -HTTP requests can be routed on features besides the verb and the URI. For example, the registration -``` -router.HandleFunc("/cliches", ClichesCreate).Schemes("https").Methods("POST") - -``` - -requires HTTPS access for a POST request to create a new cliche pair. In similar fashion, a registration might require a request to have a specified HTTP header element (e.g., an authentication credential). - -### 3\. Request validation - -The `gorilla/mux` package takes an easy, intuitive approach to request validation through regular expressions. Consider this request handler for a get one operation: -``` -router.HandleFunc("/cliches/{id:[0-9]+}", ClichesOne).Methods("GET") - -``` - -This registration rules out HTTP requests such as -``` -% curl --request GET localhost:8888/cliches/foo - -``` - -because foo is not a decimal numeral. The request results in the familiar 404 (Not Found) status code. Including the regex pattern in this handler registration ensures that the `ClichesOne` function is called to handle a request only if the request URI ends with a decimal integer value: -``` -% curl --request GET localhost:8888/cliches/3 # ok - -``` - -As a second example, consider the request -``` -% curl --request PUT --data "..." localhost:8888/cliches - -``` - -This request results in a status code of 405 (Bad Method) because the /cliches URI is registered, in the crud app, only for GET and POST requests. A PUT request, like a GET one request, must include a numeric id at the end of the URI: -``` -router.HandleFunc("/cliches/{id:[0-9]+}", ClichesEdit).Methods("PUT") - -``` - -### 4\. Concurrency issues - -The `gorilla/mux` router executes each call to a registered request handler as a separate goroutine, which means that concurrency is baked into the package. For example, if there are ten simultaneous requests such as -``` -% curl --request POST --data "..." localhost:8888/cliches - -``` - -then the `mux.Router` launches ten goroutines to execute the `ClichesCreate` handler. - -Of the five request operations GET all, GET one, POST, PUT, and DELETE, the last three alter the requested resource, the shared `clichesList` that houses the cliche pairs. Accordingly, the crudapp needs to guarantee safe concurrency by coordinating access to the `clichesList`. In different but equivalent terms, the crud app must prevent a race condition on the `clichesList`. In a production environment, a database system might be used to store a resource such as the `clichesList`, and safe concurrency then could be managed through database transactions. - -The crud app takes the recommended Go approach to safe concurrency: - - * Only a single goroutine, the resource manager started in the crud app `startServer` function, has access to the `clichesList` once the web server starts listening for requests. - * The request handlers such as `ClichesCreate` and `ClichesAll` send a (pointer to) a `crudRequest` instance to a Go channel (thread-safe by default), and the resource manager alone reads from this channel. The resource manager then performs the requested operation on the `clichesList`. - - - -The safe-concurrency architecture can be sketched as follows: -``` - crudRequest read/write - -request handlers------------->resource manager------------>clichesList - -``` - -With this architecture, no explicit locking of the `clichesList` is needed because only one goroutine, the resource manager, accesses the `clichesList` once CRUD requests start coming in. - -To keep the crud app as concurrent as possible, it’s essential to have an efficient division of labor between the request handlers, on the one side, and the single resource manager, on the other side. Here, for review, is the `ClichesCreate` request handler: -``` -func ClichesCreate(res http.ResponseWriter, req *http.Request) { - - cliche, counter := getDataFromRequest(req) - - cp := new(clichePair) - - cp.Cliche = cliche - - cp.Counter = counter - - cr := &crudRequest{verb: POST, cp: cp, confirm: make(chan string)} - - completeRequest(cr, res, "create") - -}ClichesCreateres httpResponseWriterreqclichecountergetDataFromRequestreqcpclichePaircpClicheclichecpCountercountercr&crudRequestverbPOSTcpcpconfirmcompleteRequestcrres - -``` - -`ClichesCreate` calls the utility function `getDataFromRequest`, which extracts the new cliche and counter-cliche from the POST request. The `ClichesCreate` function then creates a new `ClichePair`, sets two fields, and creates a `crudRequest` to be sent to the single resource manager. This request includes a confirmation channel, which the resource manager uses to return information back to the request handler. All of the setup work can be done without involving the resource manager because the `clichesList` is not being accessed yet. - -The request handlercalls the utility function, which extracts the new cliche and counter-cliche from the POST request. Thefunction then creates a new, sets two fields, and creates ato be sent to the single resource manager. This request includes a confirmation channel, which the resource manager uses to return information back to the request handler. All of the setup work can be done without involving the resource manager because theis not being accessed yet. - -The `completeRequest` utility function called at the end of the `ClichesCreate` function and the other request handlers -``` -completeRequest(cr, res, "create") // shown above - -``` - -brings the resource manager into play by putting a `crudRequest` into the `crudRequests` channel: -``` -func completeRequest(cr *crudRequest, res http.ResponseWriter, logMsg string) { - - crudRequests<-cr // send request to resource manager - - msg := <-cr.confirm // await confirmation string - - res.Write([]byte(msg)) // send confirmation back to requester - - logIt(logMsg) // print to the standard output - -} - -``` - -For a POST request, the resource manager calls the utility function `addPair`, which changes the `clichesList` resource: -``` -func addPair(cp *clichePair) string { - - cp.Id = masterId // assign a unique ID - - masterId++ // update the ID counter - - clichesList = append(clichesList, cp) // update the list - - return "\nCreated: " + cp.Cliche + " " + cp.Counter + "\n" - -} - -``` - -The resource manager calls similar utility functions for the other CRUD operations. It’s worth repeating that the resource manager is the only goroutine to read or write the `clichesList` once the web server starts accepting requests. - -For web applications of any type, the `gorilla/mux` package provides request routing, request validation, and related services in a straightforward, intuitive API. The crud web app highlights the package’s main features. Give the package a test drive, and you’ll likely be a buyer. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/8/http-request-routing-validation-gorillamux - -作者：[Marty Kalin][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://opensource.com/users/mkalindepauledu -[1]:https://curl.haxx.se/ -[2]:https://github.com/gorilla/mux -[3]:http://condor.depaul.edu/mkalin diff --git a/sources/tech/20180828 An Introduction to Quantum Computing with Open Source Cirq Framework.md b/sources/tech/20180828 An Introduction to Quantum Computing with Open Source Cirq Framework.md deleted file mode 100644 index 8cec20916d..0000000000 --- a/sources/tech/20180828 An Introduction to Quantum Computing with Open Source Cirq Framework.md +++ /dev/null @@ -1,228 +0,0 @@ -An Introduction to Quantum Computing with Open Source Cirq Framework -====== -As the title suggests what we are about to begin discussing, this article is an effort to understand how far we have come in Quantum Computing and where we are headed in the field in order to accelerate scientific and technological research, through an Open Source perspective with Cirq. - -First, we will introduce you to the world of Quantum Computing. We will try our best to explain the basic idea behind the same before we look into how Cirq would be playing a significant role in the future of Quantum Computing. Cirq, as you might have heard of recently, has been breaking news in the field and in this Open Science article, we will try to find out why. - - - -``` - -We went ahead and installed the Cirq library with Pip3 for Python3: -``` -pip3 install cirq - -``` - -#### Enabling Plot and PDF generation (optional) - -Optional system dependencies not install-able with pip can be installed with: -``` -sudo apt-get install python3-tk texlive-latex-base latexmk - -``` - - * python3-tk is Python’s own graphic library which enables plotting functionality. - * texlive-latex-base and latexmk enable PDF writing functionality. - - - -Later, we successfully tested Cirq with the following command and code: -``` -python3 -c 'import cirq; print(cirq.google.Foxtail)' - -``` - -We got the resulting output as: - -![][18] - -#### Configuring Pycharm IDE for Cirq - -We also configured a Python IDE [PyCharm on Ubuntu][19] to test the same results: - -Since we installed Cirq for Python3 on our Linux system, we set the path to the project interpreter in the IDE settings to be: -``` -/usr/bin/python3 - -``` - -![][20] - -In the output above, you can note that the path to the project interpreter that we just set, is shown along with the path to the test program file (test.py). An exit code of 0 shows that the program has finished executing successfully without errors. - -So, that’s a ready-to-use IDE environment where you can import the Cirq library to start programming with Python and simulate Quantum circuits. - -#### Get started with Cirq - -A good place to start are the [examples][21] that have been made available on Cirq’s Github page. - -The developers have included this [tutorial][22] on GitHub to get started with learning Cirq. If you are serious about learning Quantum Computing, they recommend an excellent book called [“Quantum Computation and Quantum Information” by Nielsen and Chuang][23]. - -#### OpenFermion-Cirq - -[OpenFermion][24] is an open source library for obtaining and manipulating representations of fermionic systems (including Quantum Chemistry) for simulation on Quantum Computers. Fermionic systems are related to the generation of [fermions][25], which according to [particle physics][26], follow [Fermi-Dirac statistics][27]. - -OpenFermion has been hailed as [a great practice tool][28] for chemists and researchers involved with [Quantum Chemistry][29]. The main focus of Quantum Chemistry is the application of [Quantum Mechanics][30] in physical models and experiments of chemical systems. Quantum Chemistry is also referred to as [Molecular Quantum Mechanics][31]. - -The advent of Cirq has now made it possible for OpenFermion to extend its functionality by providing routines and tools for using Cirq to compile and compose circuits for Quantum simulation algorithms. - -#### Google Bristlecone - -On March 5, 2018, Google presented [Bristlecone][32], their new Quantum processor, at the annual [American Physical Society meeting][33] in Los Angeles. The [gate-based superconducting system][34] provides a test platform for research into [system error rates][35] and [scalability][36] of Google’s [qubit technology][37], along-with applications in Quantum [simulation][38], [optimization][39], and [machine learning.][40] - -In the near future, Google wants to make its 72 qubit Bristlecone Quantum processor [cloud accessible][41]. Bristlecone will gradually become quite capable to perform a task that a Classical Supercomputer would not be able to complete in a reasonable amount of time. - -Cirq would make it easier for researchers to directly write programs for Bristlecone on the cloud, serving as a very convenient interface for real-time Quantum programming and testing. - -Cirq will allow us to: - - * Fine tune control over Quantum circuits, - * Specify [gate][42] behavior using native gates, - * Place gates appropriately on the device & - * Schedule the timing of these gates. - - - -### The Open Science Perspective on Cirq - -As we all know Cirq is Open Source on GitHub, its addition to the Open Source Scientific Communities, especially those which are focused on Quantum Research, can now efficiently collaborate to solve the current challenges in Quantum Computing today by developing new ways to reduce error rates and improve accuracy in the existing Quantum models. - -Had Cirq not followed an Open Source model, things would have definitely been a lot more challenging. A great initiative would have been missed out and we would not have been one step closer in the field of Quantum Computing. - -### Summary - -To summarize in the end, we first introduced you to the concept of Quantum Computing by comparing it to existing Classical Computing techniques followed by a very important video on recent developmental updates in Quantum Computing since last year. We then briefly discussed Noisy Intermediate Scale Quantum, which is what Cirq is specifically built for. - -We saw how we can install and test Cirq on an Ubuntu system. We also tested the installation for usability on an IDE environment with some resources to get started to learn the concept. - -Finally, we also saw two examples of how Cirq would be an essential advantage in the development of research in Quantum Computing, namely OpenFermion and Bristlecone. We concluded the discussion by highlighting some thoughts on Cirq with an Open Science Perspective. - -We hope we were able to introduce you to Quantum Computing with Cirq in an easy to understand manner. If you have any feedback related to the same, please let us know in the comments section. Thank you for reading and we look forward to see you in our next Open Science article. - --------------------------------------------------------------------------------- - -via: https://itsfoss.com/qunatum-computing-cirq-framework/ - -作者：[Avimanyu Bandyopadhyay][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://itsfoss.com/author/avimanyu/ -[1]:https://en.wikipedia.org/wiki/Subatomic_particle -[2]:https://en.wikipedia.org/wiki/Quantum -[3]:https://www.clerro.com/guide/491/quantum-superposition-and-entanglement-explained -[4]:https://physics.stackexchange.com/questions/148131/can-quantum-entanglement-and-quantum-superposition-be-considered-the-same-phenom -[5]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/08/bit-vs-qubit.jpg -[6]:http://www.rfwireless-world.com/Terminology/Difference-between-Bit-and-Qubit.html -[7]:https://en.wikipedia.org/wiki/Proof_by_exhaustion -[8]:https://www.explainthatstuff.com/how-supercomputers-work.html -[9]:https://arxiv.org/abs/1801.00862 -[10]:https://www.xconomy.com/san-francisco/2018/07/19/google-partners-with-zapata-on-open-source-quantum-computing-effort/ -[11]:https://www.zapatacomputing.com/about/ -[12]:https://github.com/quantumlib/Cirq -[13]:https://itsfoss.com/python-setup-linux/ -[14]:https://virtualenv.pypa.io -[15]:https://cirq.readthedocs.io/en/latest/install.html#installing-on-linux -[16]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/08/cirq-framework-linux.jpeg -[17]:https://pypi.org/project/pip/ -[18]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/08/cirq-test-output.jpg -[19]:https://itsfoss.com/install-pycharm-ubuntu/ -[20]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/08/cirq-tested-on-pycharm.jpg -[21]:https://github.com/quantumlib/Cirq/tree/master/examples -[22]:https://github.com/quantumlib/Cirq/blob/master/docs/tutorial.md -[23]:http://mmrc.amss.cas.cn/tlb/201702/W020170224608149940643.pdf -[24]:http://openfermion.org -[25]:https://en.wikipedia.org/wiki/Fermion -[26]:https://en.wikipedia.org/wiki/Particle_physics -[27]:https://en.wikipedia.org/wiki/Fermi-Dirac_statistics -[28]:https://phys.org/news/2018-03-openfermion-tool-quantum-coding.html -[29]:https://en.wikipedia.org/wiki/Quantum_chemistry -[30]:https://en.wikipedia.org/wiki/Quantum_mechanics -[31]:https://ocw.mit.edu/courses/chemical-engineering/10-675j-computational-quantum-mechanics-of-molecular-and-extended-systems-fall-2004/lecture-notes/ -[32]:https://techcrunch.com/2018/03/05/googles-new-bristlecone-processor-brings-it-one-step-closer-to-quantum-supremacy/ -[33]:http://meetings.aps.org/Meeting/MAR18/Content/3475 -[34]:https://en.wikipedia.org/wiki/Superconducting_quantum_computing -[35]:https://en.wikipedia.org/wiki/Quantum_error_correction -[36]:https://en.wikipedia.org/wiki/Scalability -[37]:https://research.googleblog.com/2015/03/a-step-closer-to-quantum-computation.html -[38]:https://research.googleblog.com/2017/10/announcing-openfermion-open-source.html -[39]:https://research.googleblog.com/2016/06/quantum-annealing-with-digital-twist.html -[40]:https://arxiv.org/abs/1802.06002 -[41]:https://www.computerworld.com.au/article/644051/google-launches-quantum-framework-cirq-plans-bristlecone-cloud-move/ -[42]:https://en.wikipedia.org/wiki/Logic_gate diff --git a/sources/tech/20180831 Publishing Markdown to HTML with MDwiki.md b/sources/tech/20180831 Publishing Markdown to HTML with MDwiki.md deleted file mode 100644 index c25239b7ba..0000000000 --- a/sources/tech/20180831 Publishing Markdown to HTML with MDwiki.md +++ /dev/null @@ -1,73 +0,0 @@ -Publishing Markdown to HTML with MDwiki -====== - - - -There are plenty of reasons to like Markdown, a simple language with an easy-to-learn syntax that can be used with any text editor. Using tools like [Pandoc][1], you can convert Markdown text to [a variety of popular formats][2], including HTML. You can also automate that conversion process in a web server. An HTML5 and JavaScript application called [MDwiki][3], created by Timo Dörr, can take a stack of Markdown files and turn them into a website when requested from a browser. The MDwiki site includes a how-to guide and other information to help you get started: - -![MDwiki site getting started][5] - -What an Mdwiki site looks like. - -Inside the web server, a basic MDwiki site looks like this: - -![MDwiki site inside web server][7] - -What the webserver folder for that site looks like. - -I renamed the MDwiki HTML file `START.HTML` for this project. There is also one Markdown file that deals with navigation and a JSON file to hold a few configuration settings. Everything else is site content. - -While the overall website design is pretty much fixed by MDwiki, the content, styling, and number of pages are not. You can view a selection of different sites generated by MDwiki at [the MDwiki site][8]. It is fair to say that MDwiki sites lack the visual appeal that a web designer could achieve—but they are functional, and users should balance their simple appearance against the speed and ease of creating and editing them. - -Markdown comes in various flavors that extend a stable core functionality for different specific purposes. MDwiki uses GitHub flavor [Markdown][9], which adds features such as formatted code blocks and syntax highlighting for popular programming languages, making it well-suited for producing program documentation and tutorials. - -MDwiki also supports what it calls "gimmicks," which add extra functionality such as embedding YouTube video content and displaying mathematical formulas. These are worth exploring if you need them for specific projects. I find MDwiki an ideal tool for creating technical documentation and educational resources. I have also discovered some tricks and hacks that might not be immediately apparent. - -MDwiki works with any modern web browser when deployed in a web server; however, you do not need a web server if you access MDwiki with Mozilla Firefox. Most MDwiki users will opt to deploy completed projects on a web server to avoid excluding potential users, but development and testing can be done with just a text editor and Firefox. Completed MDwiki projects that are loaded into a Moodle Virtual Learning Environment (VLE) can be read by any modern browser, which could be useful in educational contexts. (This is probably also true for other VLE software, but you should test that.) - -MDwiki's default color scheme is not ideal for all projects, but you can replace it with another theme downloaded from [Bootswatch.com][10]. To do this, simply open the MDwiki HTML file in an editor, take out the `extlib/css/bootstrap-3.0.0.min.css` code, and insert the downloaded Bootswatch theme. There is also an MDwiki gimmick that lets users choose a Bootswatch theme to replace the default after MDwiki loads in their browser. I often work with users who have visual impairments, and they tend to prefer high-contrast themes, with white text on a dark background. - -![MDwiki screen with Bootswatch Superhero theme][12] - -MDwiki screen using the Bootswatch Superhero theme - -MDwiki, Markdown files, and static images are fine for many purposes. However, you might sometimes want to include, say, a JavaScript slideshow or a feedback form. Markdown files can include HTML code, but mixing Markdown with HTML can get confusing. One solution is to create the feature you want in a separate HTML file and display it inside a Markdown file with an iframe tag. I took this idea from the [Twine Cookbook][13], a support site for the Twine interactive fiction engine. The Twine Cookbook doesn’t actually use MDwiki, but combining Markdown and iframe tags opens up a wide range of creative possibilities. - -Here is an example: - -This HTML will display an HTML page created by the Twine interactive fiction engine inside a Markdown file. -``` - -``` - -The result in an MDwiki-generated site looks like this: - - - -In short, MDwiki is an excellent small application that achieves its purpose extremely well. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/8/markdown-html-publishing - -作者：[Peter Cheer][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://opensource.com/users/petercheer -[1]: https://pandoc.org/ -[2]: https://opensource.com/downloads/pandoc-cheat-sheet -[3]: http://dynalon.github.io/mdwiki/#!index.md -[4]: https://opensource.com/file/407306 -[5]: https://opensource.com/sites/default/files/uploads/1_-_mdwiki_screenshot.png (MDwiki site getting started) -[6]: https://opensource.com/file/407311 -[7]: https://opensource.com/sites/default/files/uploads/2_-_mdwiki_inside_web_server.png (MDwiki site inside web server) -[8]: http://dynalon.github.io/mdwiki/#!examples.md -[9]: https://guides.github.com/features/mastering-markdown/ -[10]: https://bootswatch.com/ -[11]: https://opensource.com/file/407316 -[12]: https://opensource.com/sites/default/files/uploads/3_-_mdwiki_bootswatch_superhero.png (MDwiki screen with Bootswatch Superhero theme) -[13]: https://github.com/iftechfoundation/twine-cookbook diff --git a/sources/tech/20180911 Know Your Storage- Block, File - Object.md b/sources/tech/20180911 Know Your Storage- Block, File - Object.md deleted file mode 100644 index 24f179d9d5..0000000000 --- a/sources/tech/20180911 Know Your Storage- Block, File - Object.md +++ /dev/null @@ -1,62 +0,0 @@ -Know Your Storage: Block, File & Object -====== - - - -Dealing with the tremendous amount of data generated today presents a big challenge for companies who create or consume such data. It’s a challenge for tech companies that are dealing with related storage issues. - -“Data is growing exponentially each year, and we find that the majority of data growth is due to increased consumption and industries adopting transformational projects to expand value. Certainly, the Internet of Things (IoT) has contributed greatly to data growth, but the key challenge for software-defined storage is how to address the use cases associated with data growth,” said Michael St. Jean, principal product marketing manager, Red Hat Storage. - -Every challenge is an opportunity. “The deluge of data being generated by old and new sources today is certainly presenting us with opportunities to meet our customers escalating needs in the areas of scale, performance, resiliency, and governance,” said Tad Brockway, General Manager for Azure Storage, Media and Edge. - -### Trinity of modern software-defined storage - -There are three different kinds of storage solutions -- block, file, and object -- each serving a different purpose while working with the others. - -Block storage is the oldest form of data storage, where data is stored in fixed-length blocks or chunks of data. Block storage is used in enterprise storage environments and usually is accessed using Fibre Channel or iSCSI interface. “Block storage requires an application to map where the data is stored on the storage device,” according to SUSE’s Larry Morris, Sr. Product Manager, Software Defined Storage. - -Block storage is virtualized in storage area network and software defined storage systems, which are abstracted logical devices that reside on a shared hardware infrastructure and are created and presented to the host operating system of a server, virtual server, or hypervisor via protocols like SCSI, SATA, SAS, FCP, FCoE, or iSCSI. - -“Block storage splits a single storage volume (like a virtual or cloud storage node, or a good old fashioned hard disk) into individual instances known as blocks,” said St. Jean. - -Each block exists independently and can be formatted with its own data transfer protocol and operating system — giving users complete configuration autonomy. Because block storage systems aren’t burdened with the same investigative file-finding duties as the file storage systems, block storage is a faster storage system. Pairing that speed with configuration flexibility makes block storage ideal for raw server storage or rich media databases. - -Block storage can be used to host operating systems, applications, databases, entire virtual machines and containers. Traditionally, block storage can only be accessed by individual machine, or machines in a cluster, to which it has been presented. - -### File-based storage - -File-based storage uses a filesystem to map where the data is stored on the storage device. It’s a dominant technology used on direct- and networked-attached storage system, and it takes care of two things: organizing data and representing it to users. “With file storage, data is arranged on the server side in the exact same format as the clients see it. This allows the user to request a file by some unique identifier — like a name, location, or URL — which is communicated to the storage system using specific data transfer protocols,” said St. Jean. - -The result is a type of hierarchical file structure that can be navigated from top to bottom. File storage is layered on top of block storage, allowing users to see and access data as files and folders, but restricting access to the blocks that stand up those files and folders. - -“File storage is typically represented by shared filesystems like NFS and CIFS/SMB that can be accessed by many servers over an IP network. Access can be controlled at a file, directory, and export level via user and group permissions. File storage can be used to store files needed by multiple users and machines, application binaries, databases, virtual machines, and can be used by containers,” explained Brockway. - -### Object storage - -Object storage is the newest form of data storage, and it provides a repository for unstructured data which separates the content from the indexing and allows the concatenation of multiple files into an object. An object is a piece of data paired with any associated metadata that provides context about the bytes contained within the object (things like how old or big the data is). Those two things together — the data and metadata — make an object. - -One advantage of object storage is the unique identifier associated with each piece of data. Accessing the data involves using the unique identifier and does not require the application or user to know where the data is actually stored. Object data is accessed through APIs. - -“The data stored in objects is uncompressed and unencrypted, and the objects themselves are arranged in object stores (a central repository filled with many other objects) or containers (a package that contains all of the files an application needs to run). Objects, object stores, and containers are very flat in nature — compared to the hierarchical structure of file storage systems — which allow them to be accessed very quickly at huge scale,” explained St. Jean. - -Object stores can scale to many petabytes to accommodate the largest datasets and are a great choice for images, audio, video, logs, backups, and data used by analytics services. - -### Conclusion - -Now you know about the various types of storage and how they are used. Stay tuned to learn more about software-defined storage as we examine the topic in the future. - -Join us at [Open Source Summit + Embedded Linux Conference Europe][1] in Edinburgh, UK on October 22-24, 2018, for 100+ sessions on Linux, Cloud, Containers, AI, Community, and more. - --------------------------------------------------------------------------------- - -via: https://www.linux.com/blog/2018/9/know-your-storage-block-file-object - -作者：[Swapnil Bhartiya][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://www.linux.com/users/arnieswap -[1]: https://events.linuxfoundation.org/events/elc-openiot-europe-2018/ diff --git a/sources/tech/20180912 How to turn on an LED with Fedora IoT.md b/sources/tech/20180912 How to turn on an LED with Fedora IoT.md deleted file mode 100644 index 007cfc27ab..0000000000 --- a/sources/tech/20180912 How to turn on an LED with Fedora IoT.md +++ /dev/null @@ -1,201 +0,0 @@ -How to turn on an LED with Fedora IoT -====== - - - -Do you enjoy running Fedora, containers, and have a Raspberry Pi? What about using all three together to play with LEDs? This article introduces Fedora IoT and shows you how to install a preview image on a Raspberry Pi. You’ll also learn how to interact with GPIO in order to light up an LED. - -### What is Fedora IoT? - -Fedora IoT is one of the current Fedora Project objectives, with a plan to become a full Fedora Edition. The result will be a system that runs on ARM (aarch64 only at the moment) devices such as the Raspberry Pi, as well as on the x86_64 architecture. - -![][1] - -Fedora IoT is based on OSTree, like [Fedora Silverblue][2] and the former [Atomic Host][3]. - -### Download and install Fedora IoT - -The official Fedora IoT images are coming with the Fedora 29 release. However, in the meantime you can download a [Fedora 28-based image][4] for this experiment. - -You have two options to install the system: either flash the SD card using a dd command, or use a fedora-arm-installer tool. The Fedora Wiki offers more information about [setting up a physical device][5] for IoT. Also, remember that you might need to resize the third partition. - -Once you insert the SD card into the device, you’ll need to complete the installation by creating a user. This step requires either a serial connection, or a HDMI display with a keyboard to interact with the device. - -When the system is installed and ready, the next step is to configure a network connection. Log in to the system with the user you have just created choose one of the following options: - - * If you need to configure your network manually, run a command similar to the following. Remember to use the right addresses for your network: -``` - $ nmcli connection add con-name cable ipv4.addresses \ - 192.168.0.10/24 ipv4.gateway 192.168.0.1 \ - connection.autoconnect true ipv4.dns "8.8.8.8,1.1.1.1" \ - type ethernet ifname eth0 ipv4.method manual - -``` - - * If there’s a DHCP service on your network, run a command like this: - -``` - $ nmcli con add type ethernet con-name cable ifname eth0 -``` - - - - -### **The GPIO interface in Fedora** - -Many tutorials about GPIO on Linux focus on a legacy GPIO sysfis interface. This interface is deprecated, and the upstream Linux kernel community plan to remove it completely, due to security and other issues. - -The Fedora kernel is already compiled without this legacy interface, so there’s no /sys/class/gpio on the system. This tutorial uses a new character device /dev/gpiochipN provided by the upstream kernel. This is the current way of interacting with GPIO. - -To interact with this new device, you need to use a library and a set of command line interface tools. The common command line tools such as echo or cat won’t work with this device. - -You can install the CLI tools by installing the libgpiod-utils package. A corresponding Python library is provided by the python3-libgpiod package. - -### **Creating a container with Podman** - -[Podman][6] is a container runtime with a command line interface similar to Docker. The big advantage of Podman is it doesn’t run any daemon in the background. That’s especially useful for devices with limited resources. Podman also allows you to start containerized services with systemd unit files. Plus, it has many additional features. - -We’ll create a container in these two steps: - - 1. Create a layered image containing the required packages. - 2. Create a new container starting from our image. - - - -First, create a file Dockerfile with the content below. This tells podman to build an image based on the latest Fedora image available in the registry. Then it updates the system inside and installs some packages: - -``` -FROM fedora:latest -RUN dnf -y update -RUN dnf -y install libgpiod-utils python3-libgpiod - -``` - -You have created a build recipe of a container image based on the latest Fedora with updates, plus packages to interact with GPIO. - -Now, run the following command to build your base image: - -``` -$ sudo podman build --tag fedora:gpiobase -f ./Dockerfile - -``` - -You have just created your custom image with all the bits in place. You can play with this base container images as many times as you want without installing the packages every time you run it. - -### Working with Podman - -To verify the image is present, run the following command: - -``` -$ sudo podman images -REPOSITORY TAG IMAGE ID CREATED SIZE -localhost/fedora gpiobase 67a2b2b93b4b 10 minutes ago 488MB -docker.io/library/fedora latest c18042d7fac6 2 days ago 300MB - -``` - -Now, start the container and do some actual experiments. Containers are normally isolated and don’t have an access to the host system, including the GPIO interface. Therefore, you need to mount it inside while starting the container. To do this, use the –device option in the following command: - -``` -$ sudo podman run -it --name gpioexperiment --device=/dev/gpiochip0 localhost/fedora:gpiobase /bin/bash - -``` - -You are now inside the running container. Before you move on, here are some more container commands. For now, exit the container by typing exit or pressing **Ctrl+D**. - -To list the the existing containers, including those not currently running, such as the one you just created, run: - -``` -$ sudo podman container ls -a -CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES -64e661d5d4e8 localhost/fedora:gpiobase /bin/bash 37 seconds ago Exited (0) Less than a second ago gpioexperiment - -``` - -To create a new container, run this command: - -``` -$ sudo podman run -it --name newexperiment --device=/dev/gpiochip0 localhost/fedora:gpiobase /bin/bash - -``` - -Delete it with the following command: - -``` -$ sudo podman rm newexperiment - -``` - -### **Turn on an LED** - -Now you can use the container you already created. If you exited from the container, start it again with this command: - -``` -$ sudo podman start -ia gpioexperiment - -``` - -As already discussed, you can use the CLI tools provided by the libgpiod-utils package in Fedora. To list the available GPIO chips, run: - -``` -$ gpiodetect -gpiochip0 [pinctrl-bcm2835] (54 lines) - -``` - -To get the list of the lines exposed by a specific chip, run: - -``` -$ gpioinfo gpiochip0 - -``` - -Notice there’s no correlation between the number of physical pins and the number of lines printed by the previous command. What’s important is the BCM number, as shown on [pinout.xyz][7]. It is not advised to play with the lines that don’t have a corresponding BCM number. - -Now, connect an LED to the physical pin 40, that is BCM 21. Remember: the shorter leg of the LED (the negative leg, called the cathode) must be connected to a GND pin of the Raspberry Pi with a 330 ohm resistor, and the long leg (the anode) to the physical pin 40. - -To turn the LED on, run the following command. It will stay on until you press **Ctrl+C** : - -``` -$ gpioset --mode=wait gpiochip0 21=1 - -``` - -To light it up for a certain period of time, add the -b (run in the background) and -s NUM (how many seconds) parameters, as shown below. For example, to light the LED for 5 seconds, run: - -``` -$ gpioset -b -s 5 --mode=time gpiochip0 21=1 - -``` - -Another useful command is gpioget. It gets the status of a pin (high or low), and can be useful to detect buttons and switches. - -![Closeup of LED connection with GPIO][8] - -### **Conclusion** - -You can also play with LEDs using Python — [there are some examples here][9]. And you can also use the i2c devices inside the container as well. In addition, Podman is not strictly related to this Fedora edition. You can install it on any existing Fedora Edition, or try it on the two new OSTree-based systems in Fedora: [Fedora Silverblue][2] and [Fedora CoreOS][10]. - - --------------------------------------------------------------------------------- - -via: https://fedoramagazine.org/turnon-led-fedora-iot/ - -作者：[Alessio Ciregia][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: http://alciregi.id.fedoraproject.org/ -[1]: https://fedoramagazine.org/wp-content/uploads/2018/08/oled-1024x768.png -[2]: https://teamsilverblue.org/ -[3]: https://www.projectatomic.io/ -[4]: https://kojipkgs.fedoraproject.org/compose/iot/latest-Fedora-IoT-28/compose/IoT/ -[5]: https://fedoraproject.org/wiki/InternetOfThings/GettingStarted#Setting_up_a_Physical_Device -[6]: https://github.com/containers/libpod -[7]: https://pinout.xyz/ -[8]: https://fedoramagazine.org/wp-content/uploads/2018/08/breadboard-1024x768.png -[9]: https://github.com/brgl/libgpiod/tree/master/bindings/python/examples -[10]: https://coreos.fedoraproject.org/ diff --git a/sources/tech/20180913 Lab 1- PC Bootstrap and GCC Calling Conventions.md b/sources/tech/20180913 Lab 1- PC Bootstrap and GCC Calling Conventions.md deleted file mode 100644 index 365b5eb5f8..0000000000 --- a/sources/tech/20180913 Lab 1- PC Bootstrap and GCC Calling Conventions.md +++ /dev/null @@ -1,616 +0,0 @@ -Lab 1: PC Bootstrap and GCC Calling Conventions -====== -### Lab 1: Booting a PC - -#### Introduction - -This lab is split into three parts. The first part concentrates on getting familiarized with x86 assembly language, the QEMU x86 emulator, and the PC's power-on bootstrap procedure. The second part examines the boot loader for our 6.828 kernel, which resides in the `boot` directory of the `lab` tree. Finally, the third part delves into the initial template for our 6.828 kernel itself, named JOS, which resides in the `kernel` directory. - -##### Software Setup - -The files you will need for this and subsequent lab assignments in this course are distributed using the [Git][1] version control system. To learn more about Git, take a look at the [Git user's manual][2], or, if you are already familiar with other version control systems, you may find this [CS-oriented overview of Git][3] useful. - -The URL for the course Git repository is +0 -K> - -``` - -Each line gives the file name and line within that file of the stack frame's `eip`, followed by the name of the function and the offset of the `eip` from the first instruction of the function (e.g., `monitor+106` means the return `eip` is 106 bytes past the beginning of `monitor`). - -Be sure to print the file and function names on a separate line, to avoid confusing the grading script. - -Tip: printf format strings provide an easy, albeit obscure, way to print non-null-terminated strings like those in STABS tables. `printf("%.*s", length, string)` prints at most `length` characters of `string`. Take a look at the printf man page to find out why this works. - -You may find that some functions are missing from the backtrace. For example, you will probably see a call to `monitor()` but not to `runcmd()`. This is because the compiler in-lines some function calls. Other optimizations may cause you to see unexpected line numbers. If you get rid of the `-O2` from `GNUMakefile`, the backtraces may make more sense (but your kernel will run more slowly). - -**This completes the lab.** In the `lab` directory, commit your changes with git commit and type make handin to submit your code. - --------------------------------------------------------------------------------- - -via: https://pdos.csail.mit.edu/6.828/2018/labs/lab1/ - -作者：[csail.mit][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: -[b]: https://github.com/lujun9972 -[1]: http://www.git-scm.com/ -[2]: http://www.kernel.org/pub/software/scm/git/docs/user-manual.html -[3]: http://eagain.net/articles/git-for-computer-scientists/ -[4]: https://pdos.csail.mit.edu/6.828/2018/tools.html -[5]: https://6828.scripts.mit.edu/2018/handin.py/ -[6]: https://pdos.csail.mit.edu/6.828/2018/readings/pcasm-book.pdf -[7]: http://www.delorie.com/djgpp/doc/brennan/brennan_att_inline_djgpp.html -[8]: https://pdos.csail.mit.edu/6.828/2018/reference.html -[9]: https://pdos.csail.mit.edu/6.828/2018/readings/i386/toc.htm -[10]: http://www.intel.com/content/www/us/en/processors/architectures-software-developer-manuals.html -[11]: http://developer.amd.com/resources/developer-guides-manuals/ -[12]: http://www.qemu.org/ -[13]: http://www.gnu.org/software/gdb/ -[14]: http://web.archive.org/web/20040404164813/members.iweb.net.au/~pstorr/pcbook/book2/book2.htm -[15]: https://pdos.csail.mit.edu/6.828/2018/readings/boot-cdrom.pdf -[16]: https://pdos.csail.mit.edu/6.828/2018/labguide.html -[17]: http://www.amazon.com/C-Programming-Language-2nd/dp/0131103628/sr=8-1/qid=1157812738/ref=pd_bbs_1/104-1502762-1803102?ie=UTF8&s=books -[18]: http://library.mit.edu/F/AI9Y4SJ2L5ELEE2TAQUAAR44XV5RTTQHE47P9MKP5GQDLR9A8X-10422?func=item-global&doc_library=MIT01&doc_number=000355242&year=&volume=&sub_library= -[19]: https://pdos.csail.mit.edu/6.828/2018/labs/lab1/pointers.c -[20]: https://pdos.csail.mit.edu/6.828/2018/readings/pointers.pdf -[21]: https://pdos.csail.mit.edu/6.828/2018/readings/elf.pdf -[22]: http://en.wikipedia.org/wiki/Executable_and_Linkable_Format -[23]: https://sourceware.org/gdb/current/onlinedocs/gdb/Memory.html -[24]: http://web.cs.mun.ca/~michael/c/ascii-table.html -[25]: http://www.webopedia.com/TERM/b/big_endian.html -[26]: http://www.networksorcery.com/enp/ien/ien137.txt -[27]: http://rrbrandt.dee.ufcg.edu.br/en/docs/ansi/ diff --git a/sources/tech/20180927 Lab 2- Memory Management.md b/sources/tech/20180927 Lab 2- Memory Management.md deleted file mode 100644 index 386bf6ceaf..0000000000 --- a/sources/tech/20180927 Lab 2- Memory Management.md +++ /dev/null @@ -1,272 +0,0 @@ -Lab 2: Memory Management -====== -### Lab 2: Memory Management - -#### Introduction - -In this lab, you will write the memory management code for your operating system. Memory management has two components. - -The first component is a physical memory allocator for the kernel, so that the kernel can allocate memory and later free it. Your allocator will operate in units of 4096 bytes, called _pages_. Your task will be to maintain data structures that record which physical pages are free and which are allocated, and how many processes are sharing each allocated page. You will also write the routines to allocate and free pages of memory. - -The second component of memory management is _virtual memory_ , which maps the virtual addresses used by kernel and user software to addresses in physical memory. The x86 hardware's memory management unit (MMU) performs the mapping when instructions use memory, consulting a set of page tables. You will modify JOS to set up the MMU's page tables according to a specification we provide. - -##### Getting started - -In this and future labs you will progressively build up your kernel. We will also provide you with some additional source. To fetch that source, use Git to commit changes you've made since handing in lab 1 (if any), fetch the latest version of the course repository, and then create a local branch called `lab2` based on our lab2 branch, `origin/lab2`: - -``` - athena% cd ~/6.828/lab - athena% add git - athena% git pull - Already up-to-date. - athena% git checkout -b lab2 origin/lab2 - Branch lab2 set up to track remote branch refs/remotes/origin/lab2. - Switched to a new branch "lab2" - athena% -``` - -The git checkout -b command shown above actually does two things: it first creates a local branch `lab2` that is based on the `origin/lab2` branch provided by the course staff, and second, it changes the contents of your `lab` directory to reflect the files stored on the `lab2` branch. Git allows switching between existing branches using git checkout _branch-name_ , though you should commit any outstanding changes on one branch before switching to a different one. - -You will now need to merge the changes you made in your `lab1` branch into the `lab2` branch, as follows: - -``` - athena% git merge lab1 - Merge made by recursive. - kern/kdebug.c | 11 +++++++++-- - kern/monitor.c | 19 +++++++++++++++++++ - lib/printfmt.c | 7 +++---- - 3 files changed, 31 insertions(+), 6 deletions(-) - athena% -``` - -In some cases, Git may not be able to figure out how to merge your changes with the new lab assignment (e.g. if you modified some of the code that is changed in the second lab assignment). In that case, the git merge command will tell you which files are _conflicted_ , and you should first resolve the conflict (by editing the relevant files) and then commit the resulting files with git commit -a. - -Lab 2 contains the following new source files, which you should browse through: - - * `inc/memlayout.h` - * `kern/pmap.c` - * `kern/pmap.h` - * `kern/kclock.h` - * `kern/kclock.c` - - - -`memlayout.h` describes the layout of the virtual address space that you must implement by modifying `pmap.c`. `memlayout.h` and `pmap.h` define the `PageInfo` structure that you'll use to keep track of which pages of physical memory are free. `kclock.c` and `kclock.h` manipulate the PC's battery-backed clock and CMOS RAM hardware, in which the BIOS records the amount of physical memory the PC contains, among other things. The code in `pmap.c` needs to read this device hardware in order to figure out how much physical memory there is, but that part of the code is done for you: you do not need to know the details of how the CMOS hardware works. - -Pay particular attention to `memlayout.h` and `pmap.h`, since this lab requires you to use and understand many of the definitions they contain. You may want to review `inc/mmu.h`, too, as it also contains a number of definitions that will be useful for this lab. - -Before beginning the lab, don't forget to add -f 6.828 to get the 6.828 version of QEMU. - -##### Lab Requirements - -In this lab and subsequent labs, do all of the regular exercises described in the lab and _at least one_ challenge problem. (Some challenge problems are more challenging than others, of course!) Additionally, write up brief answers to the questions posed in the lab and a short (e.g., one or two paragraph) description of what you did to solve your chosen challenge problem. If you implement more than one challenge problem, you only need to describe one of them in the write-up, though of course you are welcome to do more. Place the write-up in a file called `answers-lab2.txt` in the top level of your `lab` directory before handing in your work. - -##### Hand-In Procedure - -When you are ready to hand in your lab code and write-up, add your `answers-lab2.txt` to the Git repository, commit your changes, and then run make handin. - -``` - athena% git add answers-lab2.txt - athena% git commit -am "my answer to lab2" - [lab2 a823de9] my answer to lab2 - 4 files changed, 87 insertions(+), 10 deletions(-) - athena% make handin -``` - -As before, we will be grading your solutions with a grading program. You can run make grade in the `lab` directory to test your kernel with the grading program. You may change any of the kernel source and header files you need to in order to complete the lab, but needless to say you must not change or otherwise subvert the grading code. - -#### Part 1: Physical Page Management - -The operating system must keep track of which parts of physical RAM are free and which are currently in use. JOS manages the PC's physical memory with _page granularity_ so that it can use the MMU to map and protect each piece of allocated memory. - -You'll now write the physical page allocator. It keeps track of which pages are free with a linked list of `struct PageInfo` objects (which, unlike xv6, are not embedded in the free pages themselves), each corresponding to a physical page. You need to write the physical page allocator before you can write the rest of the virtual memory implementation, because your page table management code will need to allocate physical memory in which to store page tables. - -Exercise 1. In the file `kern/pmap.c`, you must implement code for the following functions (probably in the order given). - -`boot_alloc()` -`mem_init()` (only up to the call to `check_page_free_list(1)`) -`page_init()` -`page_alloc()` -`page_free()` - -`check_page_free_list()` and `check_page_alloc()` test your physical page allocator. You should boot JOS and see whether `check_page_alloc()` reports success. Fix your code so that it passes. You may find it helpful to add your own `assert()`s to verify that your assumptions are correct. - -This lab, and all the 6.828 labs, will require you to do a bit of detective work to figure out exactly what you need to do. This assignment does not describe all the details of the code you'll have to add to JOS. Look for comments in the parts of the JOS source that you have to modify; those comments often contain specifications and hints. You will also need to look at related parts of JOS, at the Intel manuals, and perhaps at your 6.004 or 6.033 notes. - -#### Part 2: Virtual Memory - -Before doing anything else, familiarize yourself with the x86's protected-mode memory management architecture: namely _segmentation_ and _page translation_. - -Exercise 2. Look at chapters 5 and 6 of the [Intel 80386 Reference Manual][1], if you haven't done so already. Read the sections about page translation and page-based protection closely (5.2 and 6.4). We recommend that you also skim the sections about segmentation; while JOS uses the paging hardware for virtual memory and protection, segment translation and segment-based protection cannot be disabled on the x86, so you will need a basic understanding of it. - -##### Virtual, Linear, and Physical Addresses - -In x86 terminology, a _virtual address_ consists of a segment selector and an offset within the segment. A _linear address_ is what you get after segment translation but before page translation. A _physical address_ is what you finally get after both segment and page translation and what ultimately goes out on the hardware bus to your RAM. - -``` - Selector +--------------+ +-----------+ - ---------->| | | | - | Segmentation | | Paging | -Software | |-------->| |----------> RAM - Offset | Mechanism | | Mechanism | - ---------->| | | | - +--------------+ +-----------+ - Virtual Linear Physical - -``` - -A C pointer is the "offset" component of the virtual address. In `boot/boot.S`, we installed a Global Descriptor Table (GDT) that effectively disabled segment translation by setting all segment base addresses to 0 and limits to `0xffffffff`. Hence the "selector" has no effect and the linear address always equals the offset of the virtual address. In lab 3, we'll have to interact a little more with segmentation to set up privilege levels, but as for memory translation, we can ignore segmentation throughout the JOS labs and focus solely on page translation. - -Recall that in part 3 of lab 1, we installed a simple page table so that the kernel could run at its link address of 0xf0100000, even though it is actually loaded in physical memory just above the ROM BIOS at 0x00100000. This page table mapped only 4MB of memory. In the virtual address space layout you are going to set up for JOS in this lab, we'll expand this to map the first 256MB of physical memory starting at virtual address 0xf0000000 and to map a number of other regions of the virtual address space. - -Exercise 3. While GDB can only access QEMU's memory by virtual address, it's often useful to be able to inspect physical memory while setting up virtual memory. Review the QEMU [monitor commands][2] from the lab tools guide, especially the `xp` command, which lets you inspect physical memory. To access the QEMU monitor, press Ctrl-a c in the terminal (the same binding returns to the serial console). - -Use the xp command in the QEMU monitor and the x command in GDB to inspect memory at corresponding physical and virtual addresses and make sure you see the same data. - -Our patched version of QEMU provides an info pg command that may also prove useful: it shows a compact but detailed representation of the current page tables, including all mapped memory ranges, permissions, and flags. Stock QEMU also provides an info mem command that shows an overview of which ranges of virtual addresses are mapped and with what permissions. - -From code executing on the CPU, once we're in protected mode (which we entered first thing in `boot/boot.S`), there's no way to directly use a linear or physical address. _All_ memory references are interpreted as virtual addresses and translated by the MMU, which means all pointers in C are virtual addresses. - -The JOS kernel often needs to manipulate addresses as opaque values or as integers, without dereferencing them, for example in the physical memory allocator. Sometimes these are virtual addresses, and sometimes they are physical addresses. To help document the code, the JOS source distinguishes the two cases: the type `uintptr_t` represents opaque virtual addresses, and `physaddr_t` represents physical addresses. Both these types are really just synonyms for 32-bit integers (`uint32_t`), so the compiler won't stop you from assigning one type to another! Since they are integer types (not pointers), the compiler _will_ complain if you try to dereference them. - -The JOS kernel can dereference a `uintptr_t` by first casting it to a pointer type. In contrast, the kernel can't sensibly dereference a physical address, since the MMU translates all memory references. If you cast a `physaddr_t` to a pointer and dereference it, you may be able to load and store to the resulting address (the hardware will interpret it as a virtual address), but you probably won't get the memory location you intended. - -To summarize: - -C typeAddress type `T*` Virtual `uintptr_t` Virtual `physaddr_t` Physical - -Question - - 1. Assuming that the following JOS kernel code is correct, what type should variable `x` have, `uintptr_t` or `physaddr_t`? - -``` - mystery_t x; - char* value = return_a_pointer(); - *value = 10; - x = (mystery_t) value; - -``` - - - - -The JOS kernel sometimes needs to read or modify memory for which it knows only the physical address. For example, adding a mapping to a page table may require allocating physical memory to store a page directory and then initializing that memory. However, the kernel cannot bypass virtual address translation and thus cannot directly load and store to physical addresses. One reason JOS remaps all of physical memory starting from physical address 0 at virtual address 0xf0000000 is to help the kernel read and write memory for which it knows just the physical address. In order to translate a physical address into a virtual address that the kernel can actually read and write, the kernel must add 0xf0000000 to the physical address to find its corresponding virtual address in the remapped region. You should use `KADDR(pa)` to do that addition. - -The JOS kernel also sometimes needs to be able to find a physical address given the virtual address of the memory in which a kernel data structure is stored. Kernel global variables and memory allocated by `boot_alloc()` are in the region where the kernel was loaded, starting at 0xf0000000, the very region where we mapped all of physical memory. Thus, to turn a virtual address in this region into a physical address, the kernel can simply subtract 0xf0000000. You should use `PADDR(va)` to do that subtraction. - -##### Reference counting - -In future labs you will often have the same physical page mapped at multiple virtual addresses simultaneously (or in the address spaces of multiple environments). You will keep a count of the number of references to each physical page in the `pp_ref` field of the `struct PageInfo` corresponding to the physical page. When this count goes to zero for a physical page, that page can be freed because it is no longer used. In general, this count should be equal to the number of times the physical page appears below `UTOP` in all page tables (the mappings above `UTOP` are mostly set up at boot time by the kernel and should never be freed, so there's no need to reference count them). We'll also use it to keep track of the number of pointers we keep to the page directory pages and, in turn, of the number of references the page directories have to page table pages. - -Be careful when using `page_alloc`. The page it returns will always have a reference count of 0, so `pp_ref` should be incremented as soon as you've done something with the returned page (like inserting it into a page table). Sometimes this is handled by other functions (for example, `page_insert`) and sometimes the function calling `page_alloc` must do it directly. - -##### Page Table Management - -Now you'll write a set of routines to manage page tables: to insert and remove linear-to-physical mappings, and to create page table pages when needed. - -Exercise 4. In the file `kern/pmap.c`, you must implement code for the following functions. - -``` - - pgdir_walk() - boot_map_region() - page_lookup() - page_remove() - page_insert() - - -``` - -`check_page()`, called from `mem_init()`, tests your page table management routines. You should make sure it reports success before proceeding. - -#### Part 3: Kernel Address Space - -JOS divides the processor's 32-bit linear address space into two parts. User environments (processes), which we will begin loading and running in lab 3, will have control over the layout and contents of the lower part, while the kernel always maintains complete control over the upper part. The dividing line is defined somewhat arbitrarily by the symbol `ULIM` in `inc/memlayout.h`, reserving approximately 256MB of virtual address space for the kernel. This explains why we needed to give the kernel such a high link address in lab 1: otherwise there would not be enough room in the kernel's virtual address space to map in a user environment below it at the same time. - -You'll find it helpful to refer to the JOS memory layout diagram in `inc/memlayout.h` both for this part and for later labs. - -##### Permissions and Fault Isolation - -Since kernel and user memory are both present in each environment's address space, we will have to use permission bits in our x86 page tables to allow user code access only to the user part of the address space. Otherwise bugs in user code might overwrite kernel data, causing a crash or more subtle malfunction; user code might also be able to steal other environments' private data. Note that the writable permission bit (`PTE_W`) affects both user and kernel code! - -The user environment will have no permission to any of the memory above `ULIM`, while the kernel will be able to read and write this memory. For the address range `[UTOP,ULIM)`, both the kernel and the user environment have the same permission: they can read but not write this address range. This range of address is used to expose certain kernel data structures read-only to the user environment. Lastly, the address space below `UTOP` is for the user environment to use; the user environment will set permissions for accessing this memory. - -##### Initializing the Kernel Address Space - -Now you'll set up the address space above `UTOP`: the kernel part of the address space. `inc/memlayout.h` shows the layout you should use. You'll use the functions you just wrote to set up the appropriate linear to physical mappings. - -Exercise 5. Fill in the missing code in `mem_init()` after the call to `check_page()`. - -Your code should now pass the `check_kern_pgdir()` and `check_page_installed_pgdir()` checks. - -Question - - 2. What entries (rows) in the page directory have been filled in at this point? What addresses do they map and where do they point? In other words, fill out this table as much as possible: - | Entry | Base Virtual Address | Points to (logically): | - |-------|----------------------|---------------------------------------| - | 1023 | ? | Page table for top 4MB of phys memory | - | 1022 | ? | ? | - | . | ? | ? | - | . | ? | ? | - | . | ? | ? | - | 2 | 0x00800000 | ? | - | 1 | 0x00400000 | ? | - | 0 | 0x00000000 | [see next question] | - 3. We have placed the kernel and user environment in the same address space. Why will user programs not be able to read or write the kernel's memory? What specific mechanisms protect the kernel memory? - 4. What is the maximum amount of physical memory that this operating system can support? Why? - 5. How much space overhead is there for managing memory, if we actually had the maximum amount of physical memory? How is this overhead broken down? - 6. Revisit the page table setup in `kern/entry.S` and `kern/entrypgdir.c`. Immediately after we turn on paging, EIP is still a low number (a little over 1MB). At what point do we transition to running at an EIP above KERNBASE? What makes it possible for us to continue executing at a low EIP between when we enable paging and when we begin running at an EIP above KERNBASE? Why is this transition necessary? - - -``` -Challenge! We consumed many physical pages to hold the page tables for the KERNBASE mapping. Do a more space-efficient job using the PTE_PS ("Page Size") bit in the page directory entries. This bit was _not_ supported in the original 80386, but is supported on more recent x86 processors. You will therefore have to refer to [Volume 3 of the current Intel manuals][3]. Make sure you design the kernel to use this optimization only on processors that support it! -``` - -``` -Challenge! Extend the JOS kernel monitor with commands to: - - * Display in a useful and easy-to-read format all of the physical page mappings (or lack thereof) that apply to a particular range of virtual/linear addresses in the currently active address space. For example, you might enter `'showmappings 0x3000 0x5000'` to display the physical page mappings and corresponding permission bits that apply to the pages at virtual addresses 0x3000, 0x4000, and 0x5000. - * Explicitly set, clear, or change the permissions of any mapping in the current address space. - * Dump the contents of a range of memory given either a virtual or physical address range. Be sure the dump code behaves correctly when the range extends across page boundaries! - * Do anything else that you think might be useful later for debugging the kernel. (There's a good chance it will be!) -``` - - -##### Address Space Layout Alternatives - -The address space layout we use in JOS is not the only one possible. An operating system might map the kernel at low linear addresses while leaving the _upper_ part of the linear address space for user processes. x86 kernels generally do not take this approach, however, because one of the x86's backward-compatibility modes, known as _virtual 8086 mode_ , is "hard-wired" in the processor to use the bottom part of the linear address space, and thus cannot be used at all if the kernel is mapped there. - -It is even possible, though much more difficult, to design the kernel so as not to have to reserve _any_ fixed portion of the processor's linear or virtual address space for itself, but instead effectively to allow user-level processes unrestricted use of the _entire_ 4GB of virtual address space - while still fully protecting the kernel from these processes and protecting different processes from each other! - -``` -Challenge! Each user-level environment maps the kernel. Change JOS so that the kernel has its own page table and so that a user-level environment runs with a minimal number of kernel pages mapped. That is, each user-level environment maps just enough pages mapped so that the user-level environment can enter and leave the kernel correctly. You also have to come up with a plan for the kernel to read/write arguments to system calls. -``` - -``` -Challenge! Write up an outline of how a kernel could be designed to allow user environments unrestricted use of the full 4GB virtual and linear address space. Hint: do the previous challenge exercise first, which reduces the kernel to a few mappings in a user environment. Hint: the technique is sometimes known as " _follow the bouncing kernel_. " In your design, be sure to address exactly what has to happen when the processor transitions between kernel and user modes, and how the kernel would accomplish such transitions. Also describe how the kernel would access physical memory and I/O devices in this scheme, and how the kernel would access a user environment's virtual address space during system calls and the like. Finally, think about and describe the advantages and disadvantages of such a scheme in terms of flexibility, performance, kernel complexity, and other factors you can think of. -``` - -``` -Challenge! Since our JOS kernel's memory management system only allocates and frees memory on page granularity, we do not have anything comparable to a general-purpose `malloc`/`free` facility that we can use within the kernel. This could be a problem if we want to support certain types of I/O devices that require _physically contiguous_ buffers larger than 4KB in size, or if we want user-level environments, and not just the kernel, to be able to allocate and map 4MB _superpages_ for maximum processor efficiency. (See the earlier challenge problem about PTE_PS.) - -Generalize the kernel's memory allocation system to support pages of a variety of power-of-two allocation unit sizes from 4KB up to some reasonable maximum of your choice. Be sure you have some way to divide larger allocation units into smaller ones on demand, and to coalesce multiple small allocation units back into larger units when possible. Think about the issues that might arise in such a system. -``` - -**This completes the lab.** Make sure you pass all of the make grade tests and don't forget to write up your answers to the questions and a description of your challenge exercise solution in `answers-lab2.txt`. Commit your changes (including adding `answers-lab2.txt`) and type make handin in the `lab` directory to hand in your lab. - --------------------------------------------------------------------------------- - -via: https://pdos.csail.mit.edu/6.828/2018/labs/lab2/ - -作者：[csail.mit][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://pdos.csail.mit.edu -[b]: https://github.com/lujun9972 -[1]: https://pdos.csail.mit.edu/6.828/2018/readings/i386/toc.htm -[2]: https://pdos.csail.mit.edu/6.828/2018/labguide.html#qemu -[3]: https://pdos.csail.mit.edu/6.828/2018/readings/ia32/IA32-3A.pdf diff --git a/sources/tech/20180928 Quiet log noise with Python and machine learning.md b/sources/tech/20180928 Quiet log noise with Python and machine learning.md index 79894775ed..f1fe2f1b7f 100644 --- a/sources/tech/20180928 Quiet log noise with Python and machine learning.md +++ b/sources/tech/20180928 Quiet log noise with Python and machine learning.md @@ -1,5 +1,3 @@ -translating by Flowsnow - Quiet log noise with Python and machine learning ====== diff --git a/sources/tech/20181001 Turn your book into a website and an ePub using Pandoc.md b/sources/tech/20181001 Turn your book into a website and an ePub using Pandoc.md deleted file mode 100644 index efd2448e4d..0000000000 --- a/sources/tech/20181001 Turn your book into a website and an ePub using Pandoc.md +++ /dev/null @@ -1,265 +0,0 @@ -Translating by jlztan - -Turn your book into a website and an ePub using Pandoc -====== -Write once, publish twice using Markdown and Pandoc. - - - -Pandoc is a command-line tool for converting files from one markup language to another. In my [introduction to Pandoc][1], I explained how to convert text written in Markdown into a website, a slideshow, and a PDF. - -In this follow-up article, I'll dive deeper into [Pandoc][2], showing how to produce a website and an ePub book from the same Markdown source file. I'll use my upcoming e-book, [GRASP Principles for the Object-Oriented Mind][3], which I created using this process, as an example. - -First I will explain the file structure used for the book, then how to use Pandoc to generate a website and deploy it in GitHub. Finally, I demonstrate how to generate its companion ePub book. - -You can find the code in my [Programming Fight Club][4] GitHub repository. - -### Setting up the writing structure - -I do all of my writing in Markdown syntax. You can also use HTML, but the more HTML you introduce the highest risk that problems arise when Pandoc converts Markdown to an ePub document. My books follow the one-chapter-per-file pattern. Declare chapters using the Markdown heading H1 ( **#** ). You can put more than one chapter in each file, but putting them in separate files makes it easier to find content and do updates later. - -The meta-information follows a similar pattern: each output format has its own meta-information file. Meta-information files define information about your documents, such as text to add to your HTML or the license of your ePub. I store all of my Markdown documents in a folder named parts (this is important for the Makefile that generates the website and ePub). As an example, let's take the table of contents, the preface, and the about chapters (divided into the files toc.md, preface.md, and about.md) and, for clarity, we will leave out the remaining chapters. - -My about file might begin like: - -``` -# About this book {-} - -## Who should read this book {-} - -Before creating a complex software system one needs to create a solid foundation. -General Responsibility Assignment Software Principles (GRASP) are guidelines to assign -responsibilities to software classes in object-oriented programming. -``` - -Once the chapters are finished, the next step is to add meta-information to setup the format for the website and the ePub. - -### Generating the website - -#### Create the HTML meta-information file - -The meta-information file (web-metadata.yaml) for my website is a simple YAML file that contains information about the author, title, rights, content for the **< head>** tag, and content for the beginning and end of the HTML file. - -I recommend (at minimum) including the following fields in the web-metadata.yaml file: - -``` ---- -title: GRASP principles for the Object-oriented mind -author: Kiko Fernandez-Reyes -rights: 2017 Kiko Fernandez-Reyes, CC-BY-NC-SA 4.0 International -header-includes: -- | - \```{=html} - - - \``` -include-before: -- | - \```{=html} - If you like this book, please consider - spreading the word or - - buying me a coffee - -
- \``` -include-after: -- | - ```{=html} --- \``` ---- -``` - -Some variables to note: - - * The **header-includes** variable contains HTML that will be embedded inside the **< head>** tag. - * The line after calling a variable must be **\- |**. The next line must begin with triple backquotes that are aligned with the **|** or Pandoc will reject it. **{=html}** tells Pandoc that this is raw text and should not be processed as Markdown. (For this to work, you need to check that the **raw_attribute** extension in Pandoc is enabled. To check, type **pandoc --list-extensions | grep raw** and make sure the returned list contains an item named **+raw_html** ; the plus sign indicates it is enabled.) - * The variable **include-before** adds some HTML at the beginning of your website, and I ask readers to consider spreading the word or buying me a coffee. - * The **include-after** variable appends raw HTML at the end of the website and shows my book's license. - - - -These are only some of the fields available; take a look at the template variables in HTML (my article [introduction to Pandoc][1] covered this for LaTeX but the process is the same for HTML) to learn about others. - -#### Split the website into chapters - -The website can be generated as a whole, resulting in a long page with all the content, or split into chapters, which I think is easier to read. I'll explain how to divide the website into chapters so the reader doesn't get intimidated by a long website. - -To make the website easy to deploy on GitHub Pages, we need to create a root folder called docs (which is the root folder that GitHub Pages uses by default to render a website). Then we need to create folders for each chapter under docs, place the HTML chapters in their own folders, and the file content in a file named index.html. - -For example, the about.md file is converted to a file named index.html that is placed in a folder named about (about/index.html). This way, when users type **http://
-- --/about/**, the index.html file from the folder about will be displayed in their browser. - -The following Makefile does all of this: - -``` -# Your book files -DEPENDENCIES= toc preface about - -# Placement of your HTML files -DOCS=docs - -all: web - -web: setup $(DEPENDENCIES) - @cp $(DOCS)/toc/index.html $(DOCS) - - -# Creation and copy of stylesheet and images into -# the assets folder. This is important to deploy the -# website to Github Pages. -setup: - @mkdir -p $(DOCS) - @cp -r assets $(DOCS) - - -# Creation of folder and index.html file on a -# per-chapter basis - -$(DEPENDENCIES): - @mkdir -p $(DOCS)/$@ - @pandoc -s --toc web-metadata.yaml parts/$@.md \ - -c /assets/pandoc.css -o $(DOCS)/$@/index.html - -clean: - @rm -rf $(DOCS) - -.PHONY: all clean web setup -``` - -The option **-c /assets/pandoc.css** declares which CSS stylesheet to use; it will be fetched from **/assets/pandoc.css**. In other words, inside the **< head>** HTML tag, Pandoc adds the following line: - -``` - -``` - -To generate the website, type: - -``` -make -``` - -The root folder should contain now the following structure and files: - -``` -.---parts -| |--- toc.md -| |--- preface.md -| |--- about.md -| -|---docs - |--- assets/ - |--- index.html - |--- toc - | |--- index.html - | - |--- preface - | |--- index.html - | - |--- about - |--- index.html - -``` - -#### Deploy the website - -To deploy the website on GitHub, follow these steps: - - 1. Create a new repository - 2. Push your content to the repository - 3. Go to the GitHub Pages section in the repository's Settings and select the option for GitHub to use the content from the Master branch - - - -You can get more details on the [GitHub Pages][5] site. - -Check out [my book's website][6], generated using this process, to see the result. - -### Generating the ePub book - -#### Create the ePub meta-information file - -The ePub meta-information file, epub-meta.yaml, is similar to the HTML meta-information file. The main difference is that ePub offers other template variables, such as **publisher** and **cover-image**. Your ePub book's stylesheet will probably differ from your website's; mine uses one named epub.css. - -``` ---- -title: 'GRASP principles for the Object-oriented Mind' -publisher: 'Programming Language Fight Club' -author: Kiko Fernandez-Reyes -rights: 2017 Kiko Fernandez-Reyes, CC-BY-NC-SA 4.0 International -cover-image: assets/cover.png -stylesheet: assets/epub.css -... -``` - -Add the following content to the previous Makefile: - -``` -epub: - @pandoc -s --toc epub-meta.yaml \ - $(addprefix parts/, $(DEPENDENCIES:=.md)) -o $(DOCS)/assets/book.epub -``` - -The command for the ePub target takes all the dependencies from the HTML version (your chapter names), appends to them the Markdown extension, and prepends them with the path to the folder chapters' so Pandoc knows how to process them. For example, if **$(DEPENDENCIES)** was only **preface about** , then the Makefile would call: - -``` -@pandoc -s --toc epub-meta.yaml \ -parts/preface.md parts/about.md -o $(DOCS)/assets/book.epub -``` - -Pandoc would take these two chapters, combine them, generate an ePub, and place the book under the Assets folder. - -Here's an [example][7] of an ePub created using this process. - -### Summarizing the process - -The process to create a website and an ePub from a Markdown file isn't difficult, but there are a lot of details. The following outline may make it easier for you to follow. - - * HTML book: - * Write chapters in Markdown - * Add metadata - * Create a Makefile to glue pieces together - * Set up GitHub Pages - * Deploy - * ePub book: - * Reuse chapters from previous work - * Add new metadata file - * Create a Makefile to glue pieces together - * Set up GitHub Pages - * Deploy - - - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/10/book-to-website-epub-using-pandoc - -作者：[Kiko Fernandez-Reyes][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://opensource.com/users/kikofernandez -[1]: https://opensource.com/article/18/9/intro-pandoc -[2]: https://pandoc.org/ -[3]: https://www.programmingfightclub.com/ -[4]: https://github.com/kikofernandez/programmingfightclub -[5]: https://pages.github.com/ -[6]: https://www.programmingfightclub.com/grasp-principles/ -[7]: https://github.com/kikofernandez/programmingfightclub/raw/master/docs/web_assets/demo.epub diff --git a/sources/tech/20181002 Greg Kroah-Hartman Explains How the Kernel Community Is Securing Linux.md b/sources/tech/20181002 Greg Kroah-Hartman Explains How the Kernel Community Is Securing Linux.md deleted file mode 100644 index 768d124aa9..0000000000 --- a/sources/tech/20181002 Greg Kroah-Hartman Explains How the Kernel Community Is Securing Linux.md +++ /dev/null @@ -1,75 +0,0 @@ -Translating by qhwdw - - -Greg Kroah-Hartman Explains How the Kernel Community Is Securing Linux -============================================================ - - - -Kernel maintainer Greg Kroah-Hartman talks about how the kernel community is hardening Linux against vulnerabilities.[Creative Commons Zero][2] - -As Linux adoption expands, it’s increasingly important for the kernel community to improve the security of the world’s most widely used technology. Security is vital not only for enterprise customers, it’s also important for consumers, as 80 percent of mobile devices are powered by Linux. In this article, Linux kernel maintainer Greg Kroah-Hartman provides a glimpse into how the kernel community deals with vulnerabilities. - -### There will be bugs - - - - -Greg Kroah-Hartman[The Linux Foundation][1] - -As Linus Torvalds once said, most security holes are bugs, and bugs are part of the software development process. As long as the software is being written, there will be bugs. - -“A bug is a bug. We don’t know if a bug is a security bug or not. There is a famous bug that I fixed and then three years later Red Hat realized it was a security hole,” said Kroah-Hartman. - -There is not much the kernel community can do to eliminate bugs, but it can do more testing to find them. The kernel community now has its own security team that’s made up of kernel developers who know the core of the kernel. - -“When we get a report, we involve the domain owner to fix the issue. In some cases it’s the same people, so we made them part of the security team to speed things up,” Kroah Hartman said. But he also stressed that all parts of the kernel have to be aware of these security issues because kernel is a trusted environment and they have to protect it. - -“Once we fix things, we can put them in our stack analysis rules so that they are never reintroduced,” he said. - -Besides fixing bugs, the community also continues to add hardening to the kernel. “We have realized that we need to have mitigations. We need hardening,” said Kroah-Hartman. - -Huge efforts have been made by Kees Cook and others to take the hardening features that have been traditionally outside of the kernel and merge or adapt them for the kernel. With every kernel released, Cook provides a summary of all the new hardening features. But hardening the kernel is not enough, vendors have to enable the new features and take advantage of them. That’s not happening. - -Kroah-Hartman [releases a stable kernel every week][5], and companies pick one to support for a longer period so that device manufacturers can take advantage of it. However, Kroah-Hartman has observed that, aside from the Google Pixel, most Android phones don’t include the additional hardening features, meaning all those phones are vulnerable. “People need to enable this stuff,” he said. - -“I went out and bought all the top of the line phones based on kernel 4.4 to see which one actually updated. I found only one company that updated their kernel,” he said. “I'm working through the whole supply chain trying to solve that problem because it's a tough problem. There are many different groups involved -- the SoC manufacturers, the carriers, and so on. The point is that they have to push the kernel that we create out to people.” - -The good news is that unlike with consumer electronics, the big vendors like Red Hat and SUSE keep the kernel updated even in the enterprise environment. Modern systems with containers, pods, and virtualization make this even easier. It’s effortless to update and reboot with no downtime. It is, in fact, easier to keep things secure than it used to be. - -### Meltdown and Spectre - -No security discussion is complete without the mention of Meltdown and Spectre. The kernel community is still working on fixes as new flaws are discovered. However, Intel has changed its approach in light of these events. - -“They are reworking on how they approach security bugs and how they work with the community because they know they did it wrong,” Kroah-Hartman said. “The kernel has fixes for almost all of the big Spectre issues, but there is going to be a long tail of minor things.” - -The good news is that these Intel vulnerabilities proved that things are getting better for the kernel community. “We are doing more testing. With the latest round of security patches, we worked on our own for four months before releasing them to the world because we were embargoed. But once they hit the real world, it made us realize how much we rely on the infrastructure we have built over the years to do this kind of testing, which ensures that we don’t have bugs before they hit other people,” he said. “So things are certainly getting better.” - -The increasing focus on security is also creating more job opportunities for talented people. Since security is an area that gets eyeballs, those who want to build a career in kernel space, security is a good place to get started with. - -“If there are people who want a job to do this type of work, we have plenty of companies who would love to hire them. I know some people who have started off fixing bugs and then got hired,” Kroah-Hartman said. - -You can hear more in the video below: - -[视频](https://youtu.be/jkGVabyMh1I) - - _Check out the schedule of talks for Open Source Summit Europe and sign up to receive updates:_ - --------------------------------------------------------------------------------- - -via: https://www.linux.com/blog/2018/10/greg-kroah-hartman-explains-how-kernel-community-securing-linux-0 - -作者：[SWAPNIL BHARTIYA][a] -选题：[oska874][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://www.linux.com/users/arnieswap -[b]:https://github.com/oska874 -[1]:https://www.linux.com/licenses/category/linux-foundation -[2]:https://www.linux.com/licenses/category/creative-commons-zero -[3]:https://www.linux.com/files/images/greg-k-hpng -[4]:https://www.linux.com/files/images/kernel-securityjpg-0 -[5]:https://www.kernel.org/category/releases.html diff --git a/sources/tech/20181003 Manage NTP with Chrony.md b/sources/tech/20181003 Manage NTP with Chrony.md new file mode 100644 index 0000000000..aaec88da26 --- /dev/null +++ b/sources/tech/20181003 Manage NTP with Chrony.md @@ -0,0 +1,291 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Manage NTP with Chrony) +[#]: via: (https://opensource.com/article/18/12/manage-ntp-chrony) +[#]: author: (David Both https://opensource.com/users/dboth) + +Manage NTP with Chrony +====== +Chronyd is a better choice for most networks than ntpd for keeping computers synchronized with the Network Time Protocol. + + +> "Does anybody really know what time it is? Does anybody really care?" +> – [Chicago][1], 1969 + +Perhaps that rock group didn't care what time it was, but our computers do need to know the exact time. Timekeeping is very important to computer networks. In banking, stock markets, and other financial businesses, transactions must be maintained in the proper order, and exact time sequences are critical for that. For sysadmins and DevOps professionals, it's easier to follow the trail of email through a series of servers or to determine the exact sequence of events using log files on geographically dispersed hosts when exact times are kept on the computers in question. + +I used to work at an organization that received over 20 million emails per day and had four servers just to accept and do a basic filter on the incoming flood of email. From there, emails were sent to one of four other servers to perform more complex anti-spam assessments, then they were delivered to one of several additional servers where the emails were placed in the correct inboxes. At each layer, the emails would be sent to one of the next-level servers, selected only by the randomness of round-robin DNS. Sometimes we had to trace a new message through the system until we could determine where it "got lost," according to the pointy-haired bosses. We had to do this with frightening regularity. + +Most of that email turned out to be spam. Some people actually complained that their [joke, cat pic, recipe, inspirational saying, or other-strange-email]-of-the-day was missing and asked us to find it. We did reject those opportunities. + +Our email and other transactional searches were aided by log entries with timestamps that—today—can resolve down to the nanosecond in even the slowest of modern Linux computers. In very high-volume transaction environments, even a few microseconds of difference in the system clocks can mean sorting thousands of transactions to find the correct one(s). + +### The NTP server hierarchy + +Computers worldwide use the [Network Time Protocol][2] (NTP) to synchronize their times with internet standard reference clocks via a hierarchy of NTP servers. The primary servers are at stratum 1, and they are connected directly to various national time services at stratum 0 via satellite, radio, or even modems over phone lines. The time service at stratum 0 may be an atomic clock, a radio receiver tuned to the signals broadcast by an atomic clock, or a GPS receiver using the highly accurate clock signals broadcast by GPS satellites. + +To prevent time requests from time servers lower in the hierarchy (i.e., with a higher stratum number) from overwhelming the primary reference servers, there are several thousand public NTP stratum 2 servers that are open and available for anyone to use. Many organizations with large numbers of hosts that need an NTP server will set up their own time servers so that only one local host accesses the stratum 2 time servers, then they configure the remaining network hosts to use the local time server which, in my case, is a stratum 3 server. + +### NTP choices + +The original NTP daemon, **ntpd** , has been joined by a newer one, **chronyd**. Both keep the local host's time synchronized with the time server. Both services are available, and I have seen nothing to indicate that this will change anytime soon. + +Chrony has features that make it the better choice for most environments for the following reasons: + + * Chrony can synchronize to the time server much faster than NTP. This is good for laptops or desktops that don't run constantly. + + * It can compensate for fluctuating clock frequencies, such as when a host hibernates or enters sleep mode, or when the clock speed varies due to frequency stepping that slows clock speeds when loads are low. + + * It handles intermittent network connections and bandwidth saturation. + + * It adjusts for network delays and latency. + + * After the initial time sync, Chrony never steps the clock. This ensures stable and consistent time intervals for system services and applications. + + * Chrony can work even without a network connection. In this case, the local host or server can be updated manually. + + + + +The NTP and Chrony RPM packages are available from standard Fedora repositories. You can install both and switch between them, but modern Fedora, CentOS, and RHEL releases have moved from NTP to Chrony as their default time-keeping implementation. I have found that Chrony works well, provides a better interface for the sysadmin, presents much more information, and increases control. + +Just to make it clear, NTP is a protocol that is implemented with either NTP or Chrony. If you'd like to know more, read this [comparison between NTP and Chrony][3] as implementations of the NTP protocol. + +This article explains how to configure Chrony clients and servers on a Fedora host, but the configuration for CentOS and RHEL current releases works the same. + +### Chrony structure + +The Chrony daemon, **chronyd** , runs in the background and monitors the time and status of the time server specified in the **chrony.conf** file. If the local time needs to be adjusted, **chronyd** does it smoothly without the programmatic trauma that would occur if the clock were instantly reset to a new time. + +Chrony's **chronyc** tool allows someone to monitor the current status of Chrony and make changes if necessary. The **chronyc** utility can be used as a command that accepts subcommands, or it can be used as an interactive text-mode program. This article will explain both uses. + +### Client configuration + +The NTP client configuration is simple and requires little or no intervention. The NTP server can be defined during the Linux installation or provided by the DHCP server at boot time. The default **/etc/chrony.conf** file (shown below in its entirety) requires no intervention to work properly as a client. For Fedora, Chrony uses the Fedora NTP pool, and CentOS and RHEL have their own NTP server pools. Like many Red Hat-based distributions, the configuration file is well commented. + +``` +# Use public servers from the pool.ntp.org project. +# Please consider joining the pool (http://www.pool.ntp.org/join.html). +pool 2.fedora.pool.ntp.org iburst + +# Record the rate at which the system clock gains/losses time. +driftfile /var/lib/chrony/drift + +# Allow the system clock to be stepped in the first three updates +# if its offset is larger than 1 second. +makestep 1.0 3 + +# Enable kernel synchronization of the real-time clock (RTC). + + +# Enable hardware timestamping on all interfaces that support it. +#hwtimestamp * + +# Increase the minimum number of selectable sources required to adjust +# the system clock. +#minsources 2 + +# Allow NTP client access from local network. +#allow 192.168.0.0/16 + +# Serve time even if not synchronized to a time source. +#local stratum 10 + +# Specify file containing keys for NTP authentication. +keyfile /etc/chrony.keys + +# Get TAI-UTC offset and leap seconds from the system tz database. +leapsectz right/UTC + +# Specify directory for log files. +logdir /var/log/chrony + +# Select which information is logged. +#log measurements statistics tracking +``` + +Let's look at the current status of NTP on a virtual machine I use for testing. The **chronyc** command, when used with the **tracking** subcommand, provides statistics that report how far off the local system is from the reference server. + +``` +[root@studentvm1 ~]# chronyc tracking +Reference ID : 23ABED4D (ec2-35-171-237-77.compute-1.amazonaws.com) +Stratum : 3 +Ref time (UTC) : Fri Nov 16 16:21:30 2018 +System time : 0.000645622 seconds slow of NTP time +Last offset : -0.000308577 seconds +RMS offset : 0.000786140 seconds +Frequency : 0.147 ppm slow +Residual freq : -0.073 ppm +Skew : 0.062 ppm +Root delay : 0.041452706 seconds +Root dispersion : 0.022665167 seconds +Update interval : 1044.2 seconds +Leap status : Normal +[root@studentvm1 ~]# +``` + +The Reference ID in the first line of the result is the server the host is synchronized to—in this case, a stratum 3 reference server that was last contacted by the host at 16:21:30 2018. The other lines are described in the [chronyc(1) man page][4]. + +The **sources** subcommand is also useful because it provides information about the time source configured in **chrony.conf**. + +``` +[root@studentvm1 ~]# chronyc sources +210 Number of sources = 5 +MS Name/IP address Stratum Poll Reach LastRx Last sample +=============================================================================== +^+ 192.168.0.51 3 6 377 0 -2613us[-2613us] +/- 63ms +^+ dev.smatwebdesign.com 3 10 377 28m -2961us[-3534us] +/- 113ms +^+ propjet.latt.net 2 10 377 465 -1097us[-1085us] +/- 77ms +^* ec2-35-171-237-77.comput> 2 10 377 83 +2388us[+2395us] +/- 95ms +^+ PBX.cytranet.net 3 10 377 507 -1602us[-1589us] +/- 96ms +[root@studentvm1 ~]# +``` + +The first source in the list is the time server I set up for my personal network. The others were provided by the pool. Even though my NTP server doesn't appear in the Chrony configuration file above, my DHCP server provides its IP address for the NTP server. The "S" column—Source State—indicates with an asterisk ( ***** ) the server our host is synced to. This is consistent with the data from the **tracking** subcommand. + +The **-v** option provides a nice description of the fields in this output. + +``` +[root@studentvm1 ~]# chronyc sources -v +210 Number of sources = 5 + + .-- Source mode '^' = server, '=' = peer, '#' = local clock. + / .- Source state '*' = current synced, '+' = combined , '-' = not combined, +| / '?' = unreachable, 'x' = time may be in error, '~' = time too variable. +|| .- xxxx [ yyyy ] +/- zzzz +|| Reachability register (octal) -. | xxxx = adjusted offset, +|| Log2(Polling interval) --. | | yyyy = measured offset, +|| \ | | zzzz = estimated error. +|| | | \ +MS Name/IP address Stratum Poll Reach LastRx Last sample +=============================================================================== +^+ 192.168.0.51 3 7 377 28 -2156us[-2156us] +/- 63ms +^+ triton.ellipse.net 2 10 377 24 +5716us[+5716us] +/- 62ms +^+ lithium.constant.com 2 10 377 351 -820us[ -820us] +/- 64ms +^* t2.time.bf1.yahoo.com 2 10 377 453 -992us[ -965us] +/- 46ms +^- ntp.idealab.com 2 10 377 799 +3653us[+3674us] +/- 87ms +[root@studentvm1 ~]# +``` + +If I wanted my server to be the preferred reference time source for this host, I would add the line below to the **/etc/chrony.conf** file. + +``` +server 192.168.0.51 iburst prefer +``` + +I usually place this line just above the first pool server statement near the top of the file. There is no special reason for this, except I like to keep the server statements together. It would work just as well at the bottom of the file, and I have done that on several hosts. This configuration file is not sequence-sensitive. + +The **prefer** option marks this as the preferred reference source. As such, this host will always be synchronized with this reference source (as long as it is available). We can also use the fully qualified hostname for a remote reference server or the hostname only (without the domain name) for a local reference time source as long as the search statement is set in the **/etc/resolv.conf** file. I prefer the IP address to ensure that the time source is accessible even if DNS is not working. In most environments, the server name is probably the better option, because NTP will continue to work even if the server's IP address changes. + +If you don't have a specific reference source you want to synchronize to, it is fine to use the defaults. + +### Configuring an NTP server with Chrony + +The nice thing about the Chrony configuration file is that this single file configures the host as both a client and a server. To add a server function to our host—it will always be a client, obtaining its time from a reference server—we just need to make a couple of changes to the Chrony configuration, then configure the host's firewall to accept NTP requests. + +Open the **/etc/ ** **chrony****.conf** file in your favorite text editor and uncomment the **local stratum 10** line. This enables the Chrony NTP server to continue to act as if it were connected to a remote reference server if the internet connection fails; this enables the host to continue to be an NTP server to other hosts on the local network. + +Let's restart **chronyd** and track how the service is working for a few minutes. Before we enable our host as an NTP server, we want to test a bit. + +``` +[root@studentvm1 ~]# systemctl restart chronyd ; watch chronyc tracking +``` + +The results should look like this. The **watch** command runs the **chronyc tracking** command every two seconds so we can watch changes occur over time. + +``` +Every 2.0s: chronyc tracking studentvm1: Fri Nov 16 20:59:31 2018 + +Reference ID : C0A80033 (192.168.0.51) +Stratum : 4 +Ref time (UTC) : Sat Nov 17 01:58:51 2018 +System time : 0.001598277 seconds fast of NTP time +Last offset : +0.001791533 seconds +RMS offset : 0.001791533 seconds +Frequency : 0.546 ppm slow +Residual freq : -0.175 ppm +Skew : 0.168 ppm +Root delay : 0.094823152 seconds +Root dispersion : 0.021242738 seconds +Update interval : 65.0 seconds +Leap status : Normal +``` + +Notice that my NTP server, the **studentvm1** host, synchronizes to the host at 192.168.0.51, which is my internal network NTP server, at stratum 4. Synchronizing directly to the Fedora pool machines would result in synchronization at stratum 3. Notice also that the amount of error decreases over time. Eventually, it should stabilize with a tiny variation around a fairly small range of error. The size of the error depends upon the stratum and other network factors. After a few minutes, use Ctrl+C to break out of the watch loop. + +To turn our host into an NTP server, we need to allow it to listen on the local network. Uncomment the following line to allow hosts on the local network to access our NTP server. + +``` +# Allow NTP client access from local network. +allow 192.168.0.0/16 +``` + +Note that the server can listen for requests on any local network it's attached to. The IP address in the "allow" line is just intended for illustrative purposes. Be sure to change the IP network and subnet mask in that line to match your local network's. + +Restart **chronyd**. + +``` +[root@studentvm1 ~]# systemctl restart chronyd +``` + +To allow other hosts on your network to access this server, configure the firewall to allow inbound UDP packets on port 123. Check your firewall's documentation to find out how to do that. + +### Testing + +Your host is now an NTP server. You can test it with another host or a VM that has access to the network on which the NTP server is listening. Configure the client to use the new NTP server as the preferred server in the **/etc/chrony.conf** file, then monitor that client using the **chronyc** tools we used above. + +### Chronyc as an interactive tool + +As I mentioned earlier, **chronyc** can be used as an interactive command tool. Simply run the command without a subcommand and you get a **chronyc** command prompt. + +``` +[root@studentvm1 ~]# chronyc +chrony version 3.4 +Copyright (C) 1997-2003, 2007, 2009-2018 Richard P. Curnow and others +chrony comes with ABSOLUTELY NO WARRANTY. This is free software, and +you are welcome to redistribute it under certain conditions. See the +GNU General Public License version 2 for details. + +chronyc> +``` + +You can enter just the subcommands at this prompt. Try using the **tracking** , **ntpdata** , and **sources** commands. The **chronyc** command line allows command recall and editing for **chronyc** subcommands. You can use the **help** subcommand to get a list of possible commands and their syntax. + +### Conclusion + +Chrony is a powerful tool for synchronizing the times of client hosts, whether they are all on the local network or scattered around the globe. It's easy to configure because, despite the large number of options available, only a few configurations are required for most circumstances. + +After my client computers have synchronized with the NTP server, I like to set the system hardware clock from the system (OS) time by using the following command: + +``` +/sbin/hwclock --systohc +``` + +This command can be added as a cron job or a script in **cron.daily** to keep the hardware clock synced with the system time. + +Chrony and NTP (the service) both use the same configuration, and the files' contents are interchangeable. The man pages for [chronyd][5], [chronyc][4], and [chrony.conf][6] contain an amazing amount of information that can help you get started or learn about esoteric configuration options. + +Do you run your own NTP server? Let us know in the comments and be sure to tell us which implementation you are using, NTP or Chrony. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/12/manage-ntp-chrony + +作者：[David Both][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/dboth +[b]: https://github.com/lujun9972 +[1]: https://en.wikipedia.org/wiki/Does_Anybody_Really_Know_What_Time_It_Is%3F +[2]: https://en.wikipedia.org/wiki/Network_Time_Protocol +[3]: https://chrony.tuxfamily.org/comparison.html +[4]: https://linux.die.net/man/1/chronyc +[5]: https://linux.die.net/man/8/chronyd +[6]: https://linux.die.net/man/5/chrony.conf diff --git a/sources/tech/20181004 4 Must-Have Tools for Monitoring Linux.md b/sources/tech/20181004 4 Must-Have Tools for Monitoring Linux.md index 987809aa0d..beb3bab797 100644 --- a/sources/tech/20181004 4 Must-Have Tools for Monitoring Linux.md +++ b/sources/tech/20181004 4 Must-Have Tools for Monitoring Linux.md @@ -1,5 +1,3 @@ -### translating by way-ww - 4 Must-Have Tools for Monitoring Linux ====== diff --git a/sources/tech/20181004 Archiving web sites.md b/sources/tech/20181004 Archiving web sites.md deleted file mode 100644 index 5b7f41b689..0000000000 --- a/sources/tech/20181004 Archiving web sites.md +++ /dev/null @@ -1,121 +0,0 @@ -fuowang 翻译中 - -Archiving web sites -====== - -I recently took a deep dive into web site archival for friends who were worried about losing control over the hosting of their work online in the face of poor system administration or hostile removal. This makes web site archival an essential instrument in the toolbox of any system administrator. As it turns out, some sites are much harder to archive than others. This article goes through the process of archiving traditional web sites and shows how it falls short when confronted with the latest fashions in the single-page applications that are bloating the modern web. - -### Converting simple sites - -The days of handcrafted HTML web sites are long gone. Now web sites are dynamic and built on the fly using the latest JavaScript, PHP, or Python framework. As a result, the sites are more fragile: a database crash, spurious upgrade, or unpatched vulnerability might lose data. In my previous life as web developer, I had to come to terms with the idea that customers expect web sites to basically work forever. This expectation matches poorly with "move fast and break things" attitude of web development. Working with the [Drupal][2] content-management system (CMS) was particularly challenging in that regard as major upgrades deliberately break compatibility with third-party modules, which implies a costly upgrade process that clients could seldom afford. The solution was to archive those sites: take a living, dynamic web site and turn it into plain HTML files that any web server can serve forever. This process is useful for your own dynamic sites but also for third-party sites that are outside of your control and you might want to safeguard. - -For simple or static sites, the venerable [Wget][3] program works well. The incantation to mirror a full web site, however, is byzantine: - -``` - $ nice wget --mirror --execute robots=off --no-verbose --convert-links \ - --backup-converted --page-requisites --adjust-extension \ - --base=./ --directory-prefix=./ --span-hosts \ - --domains=www.example.com,example.com http://www.example.com/ - -``` - -The above downloads the content of the web page, but also crawls everything within the specified domains. Before you run this against your favorite site, consider the impact such a crawl might have on the site. The above command line deliberately ignores [`robots.txt`][] rules, as is now [common practice for archivists][4], and hammer the website as fast as it can. Most crawlers have options to pause between hits and limit bandwidth usage to avoid overwhelming the target site. - -The above command will also fetch "page requisites" like style sheets (CSS), images, and scripts. The downloaded page contents are modified so that links point to the local copy as well. Any web server can host the resulting file set, which results in a static copy of the original web site. - -That is, when things go well. Anyone who has ever worked with a computer knows that things seldom go according to plan; all sorts of things can make the procedure derail in interesting ways. For example, it was trendy for a while to have calendar blocks in web sites. A CMS would generate those on the fly and make crawlers go into an infinite loop trying to retrieve all of the pages. Crafty archivers can resort to regular expressions (e.g. Wget has a `--reject-regex` option) to ignore problematic resources. Another option, if the administration interface for the web site is accessible, is to disable calendars, login forms, comment forms, and other dynamic areas. Once the site becomes static, those will stop working anyway, so it makes sense to remove such clutter from the original site as well. - -### JavaScript doom - -Unfortunately, some web sites are built with much more than pure HTML. In single-page sites, for example, the web browser builds the content itself by executing a small JavaScript program. A simple user agent like Wget will struggle to reconstruct a meaningful static copy of those sites as it does not support JavaScript at all. In theory, web sites should be using [progressive enhancement][5] to have content and functionality available without JavaScript but those directives are rarely followed, as anyone using plugins like [NoScript][6] or [uMatrix][7] will confirm. - -Traditional archival methods sometimes fail in the dumbest way. When trying to build an offsite backup of a local newspaper ([pamplemousse.ca][8]), I found that WordPress adds query strings (e.g. `?ver=1.12.4`) at the end of JavaScript includes. This confuses content-type detection in the web servers that serve the archive, which rely on the file extension to send the right `Content-Type` header. When such an archive is loaded in a web browser, it fails to load scripts, which breaks dynamic websites. - -As the web moves toward using the browser as a virtual machine to run arbitrary code, archival methods relying on pure HTML parsing need to adapt. The solution for such problems is to record (and replay) the HTTP headers delivered by the server during the crawl and indeed professional archivists use just such an approach. - -### Creating and displaying WARC files - -At the [Internet Archive][9], Brewster Kahle and Mike Burner designed the [ARC][10] (for "ARChive") file format in 1996 to provide a way to aggregate the millions of small files produced by their archival efforts. The format was eventually standardized as the WARC ("Web ARChive") [specification][11] that was released as an ISO standard in 2009 and revised in 2017. The standardization effort was led by the [International Internet Preservation Consortium][12] (IIPC), which is an "international organization of libraries and other organizations established to coordinate efforts to preserve internet content for the future", according to Wikipedia; it includes members such as the US Library of Congress and the Internet Archive. The latter uses the WARC format internally in its Java-based [Heritrix crawler][13]. - -A WARC file aggregates multiple resources like HTTP headers, file contents, and other metadata in a single compressed archive. Conveniently, Wget actually supports the file format with the `--warc` parameter. Unfortunately, web browsers cannot render WARC files directly, so a viewer or some conversion is necessary to access the archive. The simplest such viewer I have found is [pywb][14], a Python package that runs a simple webserver to offer a Wayback-Machine-like interface to browse the contents of WARC files. The following set of commands will render a WARC file on `http://localhost:8080/`: - -``` - $ pip install pywb - $ wb-manager init example - $ wb-manager add example crawl.warc.gz - $ wayback - -``` - -This tool was, incidentally, built by the folks behind the [Webrecorder][15] service, which can use a web browser to save dynamic page contents. - -Unfortunately, pywb has trouble loading WARC files generated by Wget because it [followed][16] an [inconsistency in the 1.0 specification][17], which was [fixed in the 1.1 specification][18]. Until Wget or pywb fix those problems, WARC files produced by Wget are not reliable enough for my uses, so I have looked at other alternatives. A crawler that got my attention is simply called [crawl][19]. Here is how it is invoked: - -``` - $ crawl https://example.com/ - -``` - -(It does say "very simple" in the README.) The program does support some command-line options, but most of its defaults are sane: it will fetch page requirements from other domains (unless the `-exclude-related` flag is used), but does not recurse out of the domain. By default, it fires up ten parallel connections to the remote site, a setting that can be changed with the `-c` flag. But, best of all, the resulting WARC files load perfectly in pywb. - -### Future work and alternatives - -There are plenty more [resources][20] for using WARC files. In particular, there's a Wget drop-in replacement called [Wpull][21] that is specifically designed for archiving web sites. It has experimental support for [PhantomJS][22] and [youtube-dl][23] integration that should allow downloading more complex JavaScript sites and streaming multimedia, respectively. The software is the basis for an elaborate archival tool called [ArchiveBot][24], which is used by the "loose collective of rogue archivists, programmers, writers and loudmouths" at [ArchiveTeam][25] in its struggle to "save the history before it's lost forever". It seems that PhantomJS integration does not work as well as the team wants, so ArchiveTeam also uses a rag-tag bunch of other tools to mirror more complex sites. For example, [snscrape][26] will crawl a social media profile to generate a list of pages to send into ArchiveBot. Another tool the team employs is [crocoite][27], which uses the Chrome browser in headless mode to archive JavaScript-heavy sites. - -This article would also not be complete without a nod to the [HTTrack][28] project, the "website copier". Working similarly to Wget, HTTrack creates local copies of remote web sites but unfortunately does not support WARC output. Its interactive aspects might be of more interest to novice users unfamiliar with the command line. - -In the same vein, during my research I found a full rewrite of Wget called [Wget2][29] that has support for multi-threaded operation, which might make it faster than its predecessor. It is [missing some features][30] from Wget, however, most notably reject patterns, WARC output, and FTP support but adds RSS, DNS caching, and improved TLS support. - -Finally, my personal dream for these kinds of tools would be to have them integrated with my existing bookmark system. I currently keep interesting links in [Wallabag][31], a self-hosted "read it later" service designed as a free-software alternative to [Pocket][32] (now owned by Mozilla). But Wallabag, by design, creates only a "readable" version of the article instead of a full copy. In some cases, the "readable version" is actually [unreadable][33] and Wallabag sometimes [fails to parse the article][34]. Instead, other tools like [bookmark-archiver][35] or [reminiscence][36] save a screenshot of the page along with full HTML but, unfortunately, no WARC file that would allow an even more faithful replay. - -The sad truth of my experiences with mirrors and archival is that data dies. Fortunately, amateur archivists have tools at their disposal to keep interesting content alive online. For those who do not want to go through that trouble, the Internet Archive seems to be here to stay and Archive Team is obviously [working on a backup of the Internet Archive itself][37]. - --------------------------------------------------------------------------------- - -via: https://anarc.at/blog/2018-10-04-archiving-web-sites/ - -作者：[Anarcat][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://anarc.at -[1]: https://anarc.at/blog -[2]: https://drupal.org -[3]: https://www.gnu.org/software/wget/ -[4]: https://blog.archive.org/2017/04/17/robots-txt-meant-for-search-engines-dont-work-well-for-web-archives/ -[5]: https://en.wikipedia.org/wiki/Progressive_enhancement -[6]: https://noscript.net/ -[7]: https://github.com/gorhill/uMatrix -[8]: https://pamplemousse.ca/ -[9]: https://archive.org -[10]: http://www.archive.org/web/researcher/ArcFileFormat.php -[11]: https://iipc.github.io/warc-specifications/ -[12]: https://en.wikipedia.org/wiki/International_Internet_Preservation_Consortium -[13]: https://github.com/internetarchive/heritrix3/wiki -[14]: https://github.com/webrecorder/pywb -[15]: https://webrecorder.io/ -[16]: https://github.com/webrecorder/pywb/issues/294 -[17]: https://github.com/iipc/warc-specifications/issues/23 -[18]: https://github.com/iipc/warc-specifications/pull/24 -[19]: https://git.autistici.org/ale/crawl/ -[20]: https://archiveteam.org/index.php?title=The_WARC_Ecosystem -[21]: https://github.com/chfoo/wpull -[22]: http://phantomjs.org/ -[23]: http://rg3.github.io/youtube-dl/ -[24]: https://www.archiveteam.org/index.php?title=ArchiveBot -[25]: https://archiveteam.org/ -[26]: https://github.com/JustAnotherArchivist/snscrape -[27]: https://github.com/PromyLOPh/crocoite -[28]: http://www.httrack.com/ -[29]: https://gitlab.com/gnuwget/wget2 -[30]: https://gitlab.com/gnuwget/wget2/wikis/home -[31]: https://wallabag.org/ -[32]: https://getpocket.com/ -[33]: https://github.com/wallabag/wallabag/issues/2825 -[34]: https://github.com/wallabag/wallabag/issues/2914 -[35]: https://pirate.github.io/bookmark-archiver/ -[36]: https://github.com/kanishka-linux/reminiscence -[37]: http://iabak.archiveteam.org diff --git a/sources/tech/20181005 Dbxfs - Mount Dropbox Folder Locally As Virtual File System In Linux.md b/sources/tech/20181005 Dbxfs - Mount Dropbox Folder Locally As Virtual File System In Linux.md deleted file mode 100644 index 691600a4cc..0000000000 --- a/sources/tech/20181005 Dbxfs - Mount Dropbox Folder Locally As Virtual File System In Linux.md +++ /dev/null @@ -1,133 +0,0 @@ -Dbxfs – Mount Dropbox Folder Locally As Virtual File System In Linux -====== - - - -A while ago, we summarized all the possible ways to **[mount Google drive locally][1]** as a virtual file system and access the files stored in the google drive from your Linux operating system. Today, we are going to learn to mount Dropbox folder in your local file system using **dbxfs** utility. The dbxfs is used to mount your Dropbox folder locally as a virtual filesystem in Unix-like operating systems. While it is easy to [**install Dropbox client**][2] in Linux, this approach slightly differs from the official method. It is a command line dropbox client and requires no disk space for access. The dbxfs application is free, open source and written for Python 3.5+. - -### Installing dbxfs - -The dbxfs officially supports Linux and Mac OS. However, it should work on any POSIX system that provides a **FUSE-compatible library** or has the ability to mount **SMB** shares. Since it is written for Python 3.5, it can installed using **pip3** package manager. Refer the following guide if you haven’t installed PIP yet. - -And, install FUSE library as well. - -On Debian-based systems, run the following command to install FUSE: - -``` -$ sudo apt install libfuse2 - -``` - -On Fedora: - -``` -$ sudo dnf install fuse - -``` - -Once you installed all required dependencies, run the following command to install dbxfs utility: - -``` -$ pip3 install dbxfs - -``` - -### Mount Dropbox folder locally - -Create a mount point to mount your dropbox folder in your local file system. - -``` -$ mkdir ~/mydropbox - -``` - -Then, mount the dropbox folder locally using dbxfs utility as shown below: - -``` -$ dbxfs ~/mydropbox - -``` - -You will be asked to generate an access token: - - - -To generate an access token, just navigate to the URL given in the above output from your web browser and click **Allow** to authenticate Dropbox access. You need to log in to your dropbox account to complete authorization process. - -A new authorization code will be generated in the next screen. Copy the code and head back to your Terminal and paste it into cli-dbxfs prompt to finish the process. - -You will be then asked to save the credentials for future access. Type **Y** or **N** whether you want to save or decline. And then, you need to enter a passphrase twice for the new access token. - -Finally, click **Y** to accept **“/home/username/mydropbox”** as the default mount point. If you want to set different path, type **N** and enter the location of your choice. - -[![Generate access token 2][3]][4] - -All done! From now on, you can see your Dropbox folder is locally mounted in your filesystem. - - - -### Change Access Token Storage Path - -By default, the dbxfs application will store your Dropbox access token in the system keyring or an encrypted file. However, you might want to store it in a **gpg** encrypted file or something else. If so, get an access token by creating a personal app on the [Dropbox developers app console][5]. - - - -Once the app is created, click **Generate** button in the next button. This access token can be used to access your Dropbox account via the API. Don’t share your access token with anyone. - - - -Once you created an access token, encrypt it using any encryption tools of your choice, such as [**Cryptomater**][6], [**Cryptkeeper**][7], [**CryptGo**][8], [**Cryptr**][9], [**Tomb**][10], [**Toplip**][11] and [**GnuPG**][12] etc., and store it in your preferred location. - -Next edit the dbxfs configuration file and add the following line in it: - -``` -"access_token_command": ["gpg", "--decrypt", "/path/to/access/token/file.gpg"] - -``` - -You can find the dbxfs configuration file by running the following command: - -``` -$ dbxfs --print-default-config-file - -``` - -For more details, refer dbxfs help section: - -``` -$ dbxfs -h - -``` - -As you can see, mounting Dropfox folder locally in your file system using Dbxfs utility is no big deal. As far tested, dbxfs just works fine as expected. Give it a try if you’re interested to see how it works and let us know about your experience in the comment section below. - -And, that’s all for now. Hope this was useful. More good stuff to come. Stay tuned! - -Cheers! - - - --------------------------------------------------------------------------------- - -via: https://www.ostechnix.com/dbxfs-mount-dropbox-folder-locally-as-virtual-file-system-in-linux/ - -作者：[SK][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://www.ostechnix.com/author/sk/ -[1]: https://www.ostechnix.com/how-to-mount-google-drive-locally-as-virtual-file-system-in-linux/ -[2]: https://www.ostechnix.com/install-dropbox-in-ubuntu-18-04-lts-desktop/ -[3]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 -[4]: http://www.ostechnix.com/wp-content/uploads/2018/10/Generate-access-token-2.png -[5]: https://dropbox.com/developers/apps -[6]: https://www.ostechnix.com/cryptomator-open-source-client-side-encryption-tool-cloud/ -[7]: https://www.ostechnix.com/how-to-encrypt-your-personal-foldersdirectories-in-linux-mint-ubuntu-distros/ -[8]: https://www.ostechnix.com/cryptogo-easy-way-encrypt-password-protect-files/ -[9]: https://www.ostechnix.com/cryptr-simple-cli-utility-encrypt-decrypt-files/ -[10]: https://www.ostechnix.com/tomb-file-encryption-tool-protect-secret-files-linux/ -[11]: https://www.ostechnix.com/toplip-strong-file-encryption-decryption-cli-utility/ -[12]: https://www.ostechnix.com/an-easy-way-to-encrypt-and-decrypt-files-from-commandline-in-linux/ diff --git a/sources/tech/20181005 Terminalizer - A Tool To Record Your Terminal And Generate Animated Gif Images.md b/sources/tech/20181005 Terminalizer - A Tool To Record Your Terminal And Generate Animated Gif Images.md deleted file mode 100644 index 7b77a9cf73..0000000000 --- a/sources/tech/20181005 Terminalizer - A Tool To Record Your Terminal And Generate Animated Gif Images.md +++ /dev/null @@ -1,173 +0,0 @@ -thecyanbird translating - -Terminalizer – A Tool To Record Your Terminal And Generate Animated Gif Images -====== -This is know topic for most of us and i don’t want to give you the detailed information about this flow. Also, we had written many article under this topics. - -Script command is the one of the standard command to record Linux terminal sessions. Today we are going to discuss about same kind of tool called Terminalizer. - -This tool will help us to record the users terminal activity, also will help us to identify other useful information from the output. - -### What Is Terminalizer - -Terminalizer allow users to record their terminal activity and allow them to generate animated gif images. It’s highly customizable CLI tool that user can share a link for an online player, web player for a recording file. - -**Suggested Read :** -**(#)** [Script – A Simple Command To Record Your Terminal Session Activity][1] -**(#)** [Automatically Record/Capture All Users Terminal Sessions Activity In Linux][2] -**(#)** [Teleconsole – A Tool To Share Your Terminal Session Instantly To Anyone In Seconds][3] -**(#)** [tmate – Instantly Share Your Terminal Session To Anyone In Seconds][4] -**(#)** [Peek – Create a Animated GIF Recorder in Linux][5] -**(#)** [Kgif – A Simple Shell Script to Create a Gif File from Active Window][6] -**(#)** [Gifine – Quickly Create An Animated GIF Video In Ubuntu/Debian][7] - -There is no distribution official package to install this utility and we can easily install it by using Node.js. - -### How To Install Noje.js in Linux - -Node.js can be installed in multiple ways. Here, we are going to teach you the standard method. - -For Ubuntu/LinuxMint use [APT-GET Command][8] or [APT Command][9] to install Node.js - -``` -$ curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash - -$ sudo apt-get install -y nodejs - -``` - -For Debian use [APT-GET Command][8] or [APT Command][9] to install Node.js - -``` -# curl -sL https://deb.nodesource.com/setup_8.x | bash - -# apt-get install -y nodejs - -``` - -For **`RHEL/CentOS`** , use [YUM Command][10] to install tmux. - -``` -$ sudo curl --silent --location https://rpm.nodesource.com/setup_8.x | sudo bash - -$ sudo yum install epel-release -$ sudo yum -y install nodejs - -``` - -For **`Fedora`** , use [DNF Command][11] to install tmux. - -``` -$ sudo dnf install nodejs - -``` - -For **`Arch Linux`** , use [Pacman Command][12] to install tmux. - -``` -$ sudo pacman -S nodejs npm - -``` - -For **`openSUSE`** , use [Zypper Command][13] to install tmux. - -``` -$ sudo zypper in nodejs6 - -``` - -### How to Install Terminalizer - -As you have already installed prerequisite package called Node.js, now it’s time to install Terminalizer on your system. Simple run the below npm command to install Terminalizer. - -``` -$ sudo npm install -g terminalizer - -``` - -### How to Use Terminalizer - -To record your session activity using Terminalizer, just run the following Terminalizer command. Once you started the recording then play around it and finally hit `CTRL+D` to exit and save the recording. - -``` -# terminalizer record 2g-session - -defaultConfigPath -The recording session is started -Press CTRL+D to exit and save the recording - -``` - -This will save your recording session as a YAML file, in this case my filename would be 2g-session-activity.yml. -![][15] - -Just type few commands to verify this and finally hit `CTRL+D` to exit the current capture. When you hit `CTRL+D` on the terminal and you will be getting the below output. - -``` -# logout -Successfully Recorded -The recording data is saved into the file: -/home/daygeek/2g-session.yml -You can edit the file and even change the configurations. - -``` - -![][16] - -### How to Play the Recorded File - -Use the below command format to paly your recorded YAML file. Make sure, you have to input your recorded file instead of us. - -``` -# terminalizer play 2g-session - -``` - -Render a recording file as an animated gif image. - -``` -# terminalizer render 2g-session - -``` - -`Note:` Below two commands are not implemented yet in the current version and will be available in the next version. - -If you would like to share your recording to others then upload a recording file and get a link for an online player and share it. - -``` -terminalizer share 2g-session - -``` - -Generate a web player for a recording file - -``` -# terminalizer generate 2g-session - -``` - --------------------------------------------------------------------------------- - -via: https://www.2daygeek.com/terminalizer-a-tool-to-record-your-terminal-and-generate-animated-gif-images/ - -作者：[Prakash Subramanian][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://www.2daygeek.com/author/prakash/ -[1]: https://www.2daygeek.com/script-command-record-save-your-terminal-session-activity-linux/ -[2]: https://www.2daygeek.com/automatically-record-all-users-terminal-sessions-activity-linux-script-command/ -[3]: https://www.2daygeek.com/teleconsole-share-terminal-session-instantly-to-anyone-in-seconds/ -[4]: https://www.2daygeek.com/tmate-instantly-share-your-terminal-session-to-anyone-in-seconds/ -[5]: https://www.2daygeek.com/peek-create-animated-gif-screen-recorder-capture-arch-linux-mint-fedora-ubuntu/ -[6]: https://www.2daygeek.com/kgif-create-animated-gif-file-active-window-screen-recorder-capture-arch-linux-mint-fedora-ubuntu-debian-opensuse-centos/ -[7]: https://www.2daygeek.com/gifine-create-animated-gif-vedio-recorder-linux-mint-debian-ubuntu/ -[8]: https://www.2daygeek.com/apt-get-apt-cache-command-examples-manage-packages-debian-ubuntu-systems/ -[9]: https://www.2daygeek.com/apt-command-examples-manage-packages-debian-ubuntu-systems/ -[10]: https://www.2daygeek.com/yum-command-examples-manage-packages-rhel-centos-systems/ -[11]: https://www.2daygeek.com/dnf-command-examples-manage-packages-fedora-system/ -[12]: https://www.2daygeek.com/pacman-command-examples-manage-packages-arch-linux-system/ -[13]: https://www.2daygeek.com/zypper-command-examples-manage-packages-opensuse-system/ -[14]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 -[15]: https://www.2daygeek.com/wp-content/uploads/2018/10/terminalizer-record-2g-session-1.gif -[16]: https://www.2daygeek.com/wp-content/uploads/2018/10/terminalizer-play-2g-session.gif diff --git a/sources/tech/20181006 LinuxBoot for Servers - Enter Open Source, Goodbye Proprietary UEFI.md b/sources/tech/20181006 LinuxBoot for Servers - Enter Open Source, Goodbye Proprietary UEFI.md deleted file mode 100644 index 29d8a9c895..0000000000 --- a/sources/tech/20181006 LinuxBoot for Servers - Enter Open Source, Goodbye Proprietary UEFI.md +++ /dev/null @@ -1,125 +0,0 @@ -Translating by qhwdw -LinuxBoot for Servers: Enter Open Source, Goodbye Proprietary UEFI -============================================================ - -[LinuxBoot][13] is an Open Source [alternative][14] to Proprietary [UEFI][15] firmware. It was released last year and is now being increasingly preferred by leading hardware manufacturers as default firmware. Last year, LinuxBoot was warmly [welcomed][16]into the Open Source family by The Linux Foundation. - -This project was an initiative by Ron Minnich, author of LinuxBIOS and lead of [coreboot][17] at Google, in January 2017. - -Google, Facebook, [Horizon Computing Solutions][18], and [Two Sigma][19] collaborated together to develop the [LinuxBoot project][20] (formerly called [NERF][21]) for server machines based on Linux. - -Its openness allows Server users to easily customize their own boot scripts, fix issues, build their own [runtimes][22] and [reflash their firmware][23] with their own keys. They do not need to wait for vendor updates. - -Following is a video of [Ubuntu Xenial][24] booting for the first time with NERF BIOS: - -[视频](https://youtu.be/HBkZAN3xkJg) - -Let’s talk about some other advantages by comparing it to UEFI in terms of Server hardware. - -### Advantages of LinuxBoot over UEFI - - - -Here are some of the major advantages of LinuxBoot over UEFI: - -### Significantly faster startup - -It can boot up Server boards in less than twenty seconds, versus multiple minutes on UEFI. - -### Significantly more flexible - -LinuxBoot can make use of any devices, filesystems and protocols that Linux supports. - -### Potentially more secure - -Linux device drivers and filesystems have significantly more scrutiny than through UEFI. - -We can argue that UEFI is partly open with [EDK II][25] and LinuxBoot is partly closed. But it has been [addressed][26] that even such EDK II code does not have the proper level of inspection and correctness as the [Linux Kernel][27] goes through, while there is a huge amount of other Closed Source components within UEFI development. - -On the other hand, LinuxBoot has a significantly smaller amount of binaries with only a few hundred KB, compared to the 32 MB of UEFI binaries. - -To be precise, LinuxBoot fits a whole lot better into the [Trusted Computing Base][28], unlike UEFI. - -[Suggested readBest Free and Open Source Alternatives to Adobe Products for Linux][29] - -LinuxBoot has a [kexec][30] based bootloader which does not support startup on Windows/non-Linux kernels, but that is insignificant since most clouds are Linux-based Servers. - -### LinuxBoot adoption - -In 2011, the [Open Compute Project][31] was started by [Facebook][32] who [open-sourced][33] designs of some of their Servers, built to make its data centers more efficient. LinuxBoot has been tested on a few Open Compute Hardware listed as under: - -* Winterfell - -* Leopard - -* Tioga Pass - -More [OCP][34] hardware are described [here][35] in brief. The OCP Foundation runs a dedicated project on firmware through [Open System Firmware][36]. - -Some other devices that support LinuxBoot are: - -* [QEMU][9] emulated [Q35][10] systems - -* [Intel S2600wf][11] - -* [Dell R630][12] - -Last month end, [Equus Compute Solutions][37] [announced][38] the release of its [WHITEBOX OPEN™][39] M2660 and M2760 Servers, as a part of their custom, cost-optimized Open-Hardware Servers and storage platforms. Both of them support LinuxBoot to customize the Server BIOS for flexibility, improved security, and create a blazingly fast booting experience. - -### What do you think of LinuxBoot? - -LinuxBoot is quite well documented [on GitHub][40]. Do you like the features that set it apart from UEFI? Would you prefer using LinuxBoot rather than UEFI for starting up Servers, owing to the former’s open-ended development and future? Let us know in the comments below. - --------------------------------------------------------------------------------- - -via: https://itsfoss.com/linuxboot-uefi/ - -作者：[ Avimanyu Bandyopadhyay][a] -选题：[oska874][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://itsfoss.com/author/avimanyu/ -[b]:https://github.com/oska874 -[1]:https://itsfoss.com/linuxboot-uefi/# -[2]:https://itsfoss.com/linuxboot-uefi/# -[3]:https://itsfoss.com/linuxboot-uefi/# -[4]:https://itsfoss.com/linuxboot-uefi/# -[5]:https://itsfoss.com/linuxboot-uefi/# -[6]:https://itsfoss.com/linuxboot-uefi/# -[7]:https://itsfoss.com/author/avimanyu/ -[8]:https://itsfoss.com/linuxboot-uefi/#comments -[9]:https://en.wikipedia.org/wiki/QEMU -[10]:https://wiki.qemu.org/Features/Q35 -[11]:https://trmm.net/S2600 -[12]:https://trmm.net/NERF#Installing_on_a_Dell_R630 -[13]:https://www.linuxboot.org/ -[14]:https://www.phoronix.com/scan.php?page=news_item&px=LinuxBoot-OSFC-2018-State -[15]:https://itsfoss.com/check-uefi-or-bios/ -[16]:https://www.linuxfoundation.org/blog/2018/01/system-startup-gets-a-boost-with-new-linuxboot-project/ -[17]:https://en.wikipedia.org/wiki/Coreboot -[18]:http://www.horizon-computing.com/ -[19]:https://www.twosigma.com/ -[20]:https://trmm.net/LinuxBoot_34c3 -[21]:https://trmm.net/NERF -[22]:https://trmm.net/LinuxBoot_34c3#Runtimes -[23]:http://www.tech-faq.com/flashing-firmware.html -[24]:https://itsfoss.com/features-ubuntu-1604/ -[25]:https://www.tianocore.org/ -[26]:https://media.ccc.de/v/34c3-9056-bringing_linux_back_to_server_boot_roms_with_nerf_and_heads -[27]:https://medium.com/@bhumikagoyal/linux-kernel-development-cycle-52b4c55be06e -[28]:https://en.wikipedia.org/wiki/Trusted_computing_base -[29]:https://itsfoss.com/adobe-alternatives-linux/ -[30]:https://en.wikipedia.org/wiki/Kexec -[31]:https://en.wikipedia.org/wiki/Open_Compute_Project -[32]:https://github.com/facebook -[33]:https://github.com/opencomputeproject -[34]:https://www.networkworld.com/article/3266293/lan-wan/what-is-the-open-compute-project.html -[35]:http://hyperscaleit.com/ocp-server-hardware/ -[36]:https://www.opencompute.org/projects/open-system-firmware -[37]:https://www.equuscs.com/ -[38]:http://www.dcvelocity.com/products/Software_-_Systems/20180924-equus-compute-solutions-introduces-whitebox-open-m2660-and-m2760-servers/ -[39]:https://www.equuscs.com/servers/whitebox-open/ -[40]:https://github.com/linuxboot/linuxboot diff --git a/sources/tech/20181008 Taking notes with Laverna, a web-based information organizer.md b/sources/tech/20181008 Taking notes with Laverna, a web-based information organizer.md index 71adf0112b..27616a9f6e 100644 --- a/sources/tech/20181008 Taking notes with Laverna, a web-based information organizer.md +++ b/sources/tech/20181008 Taking notes with Laverna, a web-based information organizer.md @@ -1,5 +1,3 @@ -translating by cyleft - Taking notes with Laverna, a web-based information organizer ====== diff --git a/sources/tech/20181011 Exploring the Linux kernel- The secrets of Kconfig-kbuild.md b/sources/tech/20181011 Exploring the Linux kernel- The secrets of Kconfig-kbuild.md index f2885b177c..2fd085eda0 100644 --- a/sources/tech/20181011 Exploring the Linux kernel- The secrets of Kconfig-kbuild.md +++ b/sources/tech/20181011 Exploring the Linux kernel- The secrets of Kconfig-kbuild.md @@ -1,4 +1,5 @@ -translating by leemeans +Translating by Jamskr + Exploring the Linux kernel: The secrets of Kconfig/kbuild ====== Dive into understanding how the Linux config/build system works. diff --git a/sources/tech/20181022 Improve login security with challenge-response authentication.md b/sources/tech/20181022 Improve login security with challenge-response authentication.md deleted file mode 100644 index 66ed2534b0..0000000000 --- a/sources/tech/20181022 Improve login security with challenge-response authentication.md +++ /dev/null @@ -1,183 +0,0 @@ -Improve login security with challenge-response authentication -====== - - - -### Introduction - -Today, Fedora offers multiple ways to improve the secure authentication of our user accounts. Of course it has the familiar user name and password to login. It also offers additional authentication options such as biometric, fingerprint, smart card, one-time password, and even challenge-response authentication. - -Each authentication method has clear pros and cons. That, in itself, could be a topic for a rather lengthy article. Fedora Magazine has covered a few of these options previously: - - -+ [Using the YubiKey4 with Fedora][1] -+ [Fedora 28: Better smart card support in OpenSSH][2] - - -One of the most secure methods in modern Fedora releases is offline hardware challenge-response. It’s also one of the easiest to deploy. Here’s how. - -### Challenge-response authentication - -Technically, when you provide a password, you’re responding to a user name challenge. The offline challenge response covered here requires your user name first. Next, Fedora challenges you to provide an encrypted physical hardware token. The token responds to the challenge with another encrypted key it stores via the Pluggable Authentication Modules (PAM) framework. Finally, Fedora prompts you for the password. This prevents someone from just using a found hardware token, or just using a user name and password without the correct encrypted key. - -This means that in addition to your user name and password, you must have previously registered one or more encrypted hardware tokens with the OS. And you have to provide that physical hardware token to be able to authenticate with your user name. - -Some challenge-response methods, like one time passwords (OTP), take an encrypted code key on the hardware token, and pass that key across the network to a remote authentication server. The server then tells Fedora’s PAM framework if it’s is a valid token for that user name. This is great if the authentication server(s) are on the local network. The downside is if the network connection is down or you’re working remote without a network connection, you can’t use this remote authentication method. You could be locked out of the system until you can connect through the network to the server. - -Sometimes a workplace requires use of Yubikey One Time Passwords (OTP) configuration. However, on home or personal systems you may prefer a local challenge-response configuration. Everything is local, and the method requires no remote network calls. The following process works on Fedora 27, 28, and 29. - -### Preparation - -#### Hardware token keys - -First you need a secure hardware token key. Specifically, this process requires a Yubikey 4, Yubikey NEO, or a recently released Yubikey 5 series device which also supports FIDO2. You should purchase two of them to provide a backup in case one becomes lost or damaged. You can use these keys on numerous workstations. The simpler FIDO or FIDO U2F only versions don’t work for this process, but are great for online services that use FIDO. - -#### Backup, backup, and backup - -Next, make a backup of all your important data. You may want to test the configuration in a Fedora 27/28/29 cloned VM to make sure you understand the process before setting up your personal workstation. - -#### Updating and installing - -Now make sure Fedora is up to date. Then install the required Fedora Yubikey packages via these dnf commands: - -``` -$ sudo dnf upgrade -$ sudo dnf install ykclient* ykpers* pam_yubico* -$ cd -``` - -If you’re in a VM environment, such as Virtual Box, make sure the Yubikey device is inserted in a USB port, and enable USB access to the Yubikey in the VM control. - -### Configuring Yubikey - -Verify that your user account has access to the USB Yubikey: - -``` -$ ykinfo -v -version: 3.5.0 -``` - -If the YubiKey is not detected, the following error message appears: - -``` -Yubikey core error: no yubikey present -``` - -Next, initialize each of your new Yubikeys with the following ykpersonalize command. This sets up the Yubikey configuration slot 2 with a Challenge Response using the HMAC-SHA1 algorithm, even with less than 64 characters. If you have already setup your Yubikeys for challenge-response, you don’t need to run ykpersonalize again. - -``` -ykpersonalize -2 -ochal-resp -ochal-hmac -ohmac-lt64 -oserial-api-visible -``` - -Some users leave the YubiKey in their workstation while using it, and even use challenge-response for virtual machines. However, for more security you may prefer to manually trigger the Yubikey to respond to challenge. - -To add that manual challenge button trigger, add the -ochal-btn-trig flag. This flag causes the Yubikey to flash the yubikey LED on a request. It waits for you to press the button on the hardware key area within 15 seconds to produce the response key. - -``` -$ ykpersonalize -2 -ochal-resp -ochal-hmac -ohmac-lt64 -ochal-btn-trig -oserial-api-visible -``` - -Do this for each of your new hardware keys, only once per key. Once you have programmed your keys, store the Yubikey configuration to ~/.yubico with the following command: - -``` -$ ykpamcfg -2 -v -debug: util.c:222 (check_firmware_version): YubiKey Firmware version: 4.3.4 - -Sending 63 bytes HMAC challenge to slot 2 -Sending 63 bytes HMAC challenge to slot 2 -Stored initial challenge and expected response in '/home/chuckfinley/.yubico/challenge-9992567'. -``` - -If you are setting up multiple keys for backup purposes, configure all the keys the same, and store each key’s challenge-response using the ykpamcfg utility. If you run the command ykpersonalize on an existing registered key, you must store the configuration again. - -### Configuring /etc/pam.d/sudo - -Now to verify this configuration worked, **in the same terminal window** you’ll setup sudo to require the use of the Yubikey challenge-response. Insert the following line into the /etc/pam.d/sudo file: - -``` -auth required pam_yubico.so mode=challenge-response -``` - -Insert the above auth line into the file above the auth include system-auth line. Then save the file and exit the editor. In a default Fedora 29 setup, /etc/pam.d/sudo should now look like this: - -``` -#%PAM-1.0 -auth required pam_yubico.so mode=challenge-response -auth include system-auth -account include system-auth -password include system-auth -session optional pam_keyinit.so revoke -session required pam_limits.so -session include system-auth -``` - -**Keep this original terminal window open** , and test by opening another new terminal window. In the new terminal window type: - -``` -$ sudo echo testing -``` - -You should notice the LED blinking on the key. Tap the Yubikey button and you should see a prompt for your sudo password. After you enter your password, you should see “testing” echoed in the terminal screen. - -Now test to ensure a correct failure. Start another terminal window and remove the Yubikey from the USB port. Verify that sudo no longer works without the Yubikey with this command: - -``` -$ sudo echo testing fail -``` - -You should immediately be prompted for the sudo password. Even if you enter the password, it should fail. - -### Configuring Gnome Desktop Manager - -Once your testing is complete, now you can add challenge-response support for the graphical login. Re-insert your Yubikey into the USB port. Next you’ll add the following line to the /etc/pam.d/gdm-password file: - -``` -auth required pam_yubico.so mode=challenge-response -``` - -Open a terminal window, and issue the following command. You can use another editor if desired: - -``` -$ sudo vi /etc/pam.d/gdm-password -``` - -You should see the yubikey LED blinking. Press the yubikey button, then enter the password at the prompt. - -Modify the /etc/pam.d/gdm-password file to add the new auth line above the existing line auth substack password-auth. The top of the file should now look like this: - -``` -auth [success=done ignore=ignore default=bad] pam_selinux_permit.so -auth required pam_yubico.so mode=challenge-response -auth substack password-auth -auth optional pam_gnome_keyring.so -auth include postlogin - -account required pam_nologin.so -``` - -Save the changes and exit the editor. If you use vi, the key sequence is to hit the **Esc** key, then type wq! at the prompt to save and exit. - -### Conclusion - -Now log out of GNOME. With the Yubikey inserted into the USB port, click on your user name in the graphical login. The Yubikey LED begins to flash. Touch the button, and you will be prompted for your password. - -If you lose the Yubikey, you can still use the secondary backup Yubikey in addition to your set password. You can also add additional Yubikey configurations to your user account. - -If someone gains access to your password, they still can’t login without your physical hardware Yubikey. Congratulations! You’ve now dramatically increased the security of your workstation login. - --------------------------------------------------------------------------------- - -via: https://fedoramagazine.org/login-challenge-response-authentication/ - -作者：[nabooengineer][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://fedoramagazine.org/author/nabooengineer/ -[b]: https://github.com/lujun9972 -[1]: https://fedoramagazine.org/using-the-yubikey4-with-fedora/ -[2]: https://fedoramagazine.org/fedora-28-better-smart-card-support-openssh/ - diff --git a/sources/tech/20181025 How to write your favorite R functions in Python.md b/sources/tech/20181025 How to write your favorite R functions in Python.md deleted file mode 100644 index a06d3557b9..0000000000 --- a/sources/tech/20181025 How to write your favorite R functions in Python.md +++ /dev/null @@ -1,153 +0,0 @@ -How to write your favorite R functions in Python -====== -R or Python? This Python script mimics convenient R-style functions for doing statistics nice and easy. - - - -One of the great modern battles of data science and machine learning is "Python vs. R." There is no doubt that both have gained enormous ground in recent years to become top programming languages for data science, predictive analytics, and machine learning. In fact, according to a recent IEEE article, Python overtook C++ as the [top programming language][1] and R firmly secured its spot in the top 10. - -However, there are some fundamental differences between these two. [R was developed primarily][2] as a tool for statistical analysis and quick prototyping of a data analysis problem. Python, on the other hand, was developed as a general purpose, modern object-oriented language in the same vein as C++ or Java but with a simpler learning curve and more flexible demeanor. Consequently, R continues to be extremely popular among statisticians, quantitative biologists, physicists, and economists, whereas Python has slowly emerged as the top language for day-to-day scripting, automation, backend web development, analytics, and general machine learning frameworks and has an extensive support base and open source development community work. - -### Mimicking functional programming in a Python environment - -[R's nature as a functional programming language][3] provides users with an extremely simple and compact interface for quick calculations of probabilities and essential descriptive/inferential statistics for a data analysis problem. For example, wouldn't it be great to be able to solve the following problems with just a single, compact function call? - - * How to calculate the mean/median/mode of a data vector. - * How to calculate the cumulative probability of some event following a normal distribution. What if the distribution is Poisson? - * How to calculate the inter-quartile range of a series of data points. - * How to generate a few random numbers following a Student's t-distribution. - - - -The R programming environment can do all of these. - -On the other hand, Python's scripting ability allows analysts to use those statistics in a wide variety of analytics pipelines with limitless sophistication and creativity. - -To combine the advantages of both worlds, you just need a simple Python-based wrapper library that contains the most commonly used functions pertaining to probability distributions and descriptive statistics defined in R-style. This enables you to call those functions really fast without having to go to the proper Python statistical libraries and figure out the whole list of methods and arguments. - -### Python wrapper script for most convenient R-functions - -[I wrote a Python script][4] to define the most convenient and widely used R-functions in simple, statistical analysis—in Python. After importing this script, you will be able to use those R-functions naturally, just like in an R programming environment. - -The goal of this script is to provide simple Python subroutines mimicking R-style statistical functions for quickly calculating density/point estimates, cumulative distributions, and quantiles and generating random variates for important probability distributions. - -To maintain the spirit of R styling, the script uses no class hierarchy and only raw functions are defined in the file. Therefore, a user can import this one Python script and use all the functions whenever they're needed with a single name call. - -Note that I use the word mimic. Under no circumstance am I claiming to emulate R's true functional programming paradigm, which consists of a deep environmental setup and complex relationships between those environments and objects. This script allows me (and I hope countless other Python users) to quickly fire up a Python program or Jupyter notebook, import the script, and start doing simple descriptive statistics in no time. That's the goal, nothing more, nothing less. - -If you've coded in R (maybe in grad school) and are just starting to learn and use Python for data analysis, you will be happy to see and use some of the same well-known functions in your Jupyter notebook in a manner similar to how you use them in your R environment. - -Whatever your reason, using this script is fun. - -### Simple examples - -To start, just import the script and start working with lists of numbers as if they were data vectors in R. - -``` -from R_functions import * -lst=[20,12,16,32,27,65,44,45,22,18] - -``` - -Say you want to calculate the [Tuckey five-number][5] summary from a vector of data points. You just call one simple function, **fivenum** , and pass on the vector. It will return the five-number summary in a NumPy array. - -``` -lst=[20,12,16,32,27,65,44,45,22,18] -fivenum(lst) -> array([12. , 18.5, 24.5, 41. , 65. ]) -``` - -Maybe you want to know the answer to the following question: - -Suppose a machine outputs 10 finished goods per hour on average with a standard deviation of 2. The output pattern follows a near normal distribution. What is the probability that the machine will output at least 7 but no more than 12 units in the next hour? - -The answer is essentially this: - - - -You can obtain the answer with just one line of code using **pnorm** : - -``` -pnorm(12,10,2)-pnorm(7,10,2) -> 0.7745375447996848 -``` - -Or maybe you need to answer the following: - -Suppose you have a loaded coin with the probability of turning heads up 60% every time you toss it. You are playing a game of 10 tosses. How do you plot and map out the chances of all the possible number of wins (from 0 to 10) with this coin? - -You can obtain a nice bar chart with just a few lines of code using just one function, **dbinom** : - -``` -probs=[] -import matplotlib.pyplot as plt -for i in range(11): - probs.append(dbinom(i,10,0.6)) -plt.bar(range(11),height=probs) -plt.grid(True) -plt.show() -``` - - - -### Simple interface for probability calculations - -R offers an extremely simple and intuitive interface for quick calculations from essential probability distributions. The interface goes like this: - - * **d** {distribution} gives the density function value at a point **x** - * **p** {distribution} gives the cumulative value at a point **x** - * **q** {distribution} gives the quantile function value at a probability **p** - * **r** {distribution} generates one or multiple random variates - - - -In our implementation, we stick to this interface and its associated argument list so you can execute these functions exactly like you would in an R environment. - -### Currently implemented functions - -The following R-style functions are implemented in the script for fast calling. - - * Mean, median, variance, standard deviation - * Tuckey five-number summary, IQR - * Covariance of a matrix or between two vectors - * Density, cumulative probability, quantile function, and random variate generation for the following distributions: normal, uniform, binomial, Poisson, F, Student's t, Chi-square, beta, and gamma. - - - -### Work in progress - -Obviously, this is a work in progress, and I plan to add some other convenient R-functions to this script. For example, in R, a single line of command **lm** can get you an ordinary least-square fitted model to a numerical dataset with all the necessary inferential statistics (P-values, standard error, etc.). This is powerfully brief and compact! On the other hand, standard linear regression problems in Python are often tackled using [Scikit-learn][6], which needs a bit more scripting for this use, so I plan to incorporate this single function linear model fitting feature using Python's [statsmodels][7] backend. - -If you like and use this script in your work, please help others find it by starring or forking its [GitHub repository][8]. Also, you can check my other [GitHub repos][9] for fun code snippets in Python, R, or MATLAB and some machine learning resources. - -If you have any questions or ideas to share, please contact me at [tirthajyoti[AT]gmail.com][10]. If you are, like me, passionate about machine learning and data science, please [add me on LinkedIn][11] or [follow me on Twitter. ][12] - -Originally published on [Towards Data Science][13]. Reposted under [CC BY-SA 4.0][14]. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/10/write-favorite-r-functions-python - -作者：[Tirthajyoti Sarkar][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://opensource.com/users/tirthajyoti -[b]: https://github.com/lujun9972 -[1]: https://spectrum.ieee.org/at-work/innovation/the-2018-top-programming-languages -[2]: https://www.coursera.org/lecture/r-programming/overview-and-history-of-r-pAbaE -[3]: http://adv-r.had.co.nz/Functional-programming.html -[4]: https://github.com/tirthajyoti/StatsUsingPython/blob/master/R_Functions.py -[5]: https://en.wikipedia.org/wiki/Five-number_summary -[6]: http://scikit-learn.org/stable/ -[7]: https://www.statsmodels.org/stable/index.html -[8]: https://github.com/tirthajyoti/StatsUsingPython -[9]: https://github.com/tirthajyoti?tab=repositories -[10]: mailto:tirthajyoti@gmail.com -[11]: https://www.linkedin.com/in/tirthajyoti-sarkar-2127aa7/ -[12]: https://twitter.com/tirthajyotiS -[13]: https://towardsdatascience.com/how-to-write-your-favorite-r-functions-in-python-11e1e9c29089 -[14]: https://creativecommons.org/licenses/by-sa/4.0/ diff --git a/sources/tech/20181025 Monitoring database health and behavior- Which metrics matter.md b/sources/tech/20181025 Monitoring database health and behavior- Which metrics matter.md deleted file mode 100644 index 520f08342b..0000000000 --- a/sources/tech/20181025 Monitoring database health and behavior- Which metrics matter.md +++ /dev/null @@ -1,82 +0,0 @@ -Monitoring database health and behavior: Which metrics matter? -====== -Monitoring your database can be overwhelming or seem not important. Here's how to do it right. - - -We don’t talk about our databases enough. In this age of instrumentation, we monitor our applications, our infrastructure, and even our users, but we sometimes forget that our database deserves monitoring, too. That’s largely because most databases do their job so well that we simply trust them to do it. Trust is great, but confirmation of our assumptions is even better. - - - -### Why monitor your databases? - -There are plenty of reasons to monitor your databases, most of which are the same reasons you'd monitor any other part of your systems: Knowing what’s going on in the various components of your applications makes you a better-informed developer who makes smarter decisions. - - - -More specifically, databases are great indicators of system health and behavior. Odd behavior in the database can point to problem areas in your applications. Alternately, when there’s odd behavior in your application, you can use database metrics to help expedite the debugging process. - -### The problem - -The slightest investigation reveals one problem with monitoring databases: Databases have a lot of metrics. "A lot" is an understatement—if you were Scrooge McDuck, you could swim through all of the metrics available. If this were Wrestlemania, the metrics would be folding chairs. Monitoring them all doesn’t seem practical, so how do you decide which metrics to monitor? - - - -### The solution - -The best way to start monitoring databases is to identify some foundational, database-agnostic metrics. These metrics create a great start to understanding the lives of your databases. - -### Throughput: How much is the database doing? - -The easiest way to start monitoring a database is to track the number of requests the database receives. We have high expectations for our databases; we expect them to store data reliably and handle all of the queries we throw at them, which could be one massive query a day or millions of queries from users all day long. Throughput can tell you which of those is true. - -You can also group requests by type (reads, writes, server-side, client-side, etc.) to begin analyzing the traffic. - -### Execution time: How long does it take the database to do its job? - -This metric seems obvious, but it often gets overlooked. You don’t just want to know how many requests the database received, but also how long the database spent on each request. It’s important to approach execution time with context, though: What's slow for a time-series database like InfluxDB isn’t the same as what's slow for a relational database like MySQL. Slow in InfluxDB might mean milliseconds, whereas MySQL’s default value for its `SLOW_QUERY` variable is ten seconds. - - - -Monitoring execution time is not the same thing as improving execution time, so beware of the temptation to spend time on optimizations if you have other problems in your app to fix. - -### Concurrency: How many jobs is the database doing at the same time? - -Once you know how many requests the database is handling and how long each one takes, you need to add a layer of complexity to start getting real value from these metrics. - -If the database receives ten requests and each one takes ten seconds to complete, is the database busy for 100 seconds, ten seconds—or somewhere in between? The number of concurrent tasks changes the way the database’s resources are used. When you consider things like the number of connections and threads, you’ll start to get a fuller picture of your database metrics. - -Concurrency can also affect latency, which includes not only the time it takes for the task to be completed (execution time) but also the time the task needs to wait before it’s handled. - -### Utilization: What percentage of the time was the database busy? - -Utilization is a culmination of throughput, execution time, and concurrency to determine how often the database was available—or alternatively, how often the database was too busy to respond to a request. - - - -This metric is particularly useful for determining the overall health and performance of your database. If it’s available to respond to requests only 80% of the time, you can reallocate resources, work on optimization, or otherwise make changes to get closer to high availability. - -### The good news - -It can seem overwhelming to monitor and analyze, especially because most of us aren’t database experts and we may not have time to devote to understanding these metrics. But the good news is that most of this work is already done for us. Many databases have an internal performance database (Postgres: pg_stats, CouchDB: Runtime_Statistics, InfluxDB: _internal, etc.), which is designed by database engineers to monitor the metrics that matter for that particular database. You can see things as broad as the number of slow queries or as detailed as the average microseconds each event in the database takes. - -### Conclusion - -Databases create enough metrics to keep us all busy for a long time, and while the internal performance databases are full of useful information, it’s not always clear which metrics you should care about. Start with throughput, execution time, concurrency, and utilization, which provide enough information for you to start understanding the patterns in your database. - - - -Are you monitoring your databases? Which metrics have you found to be useful? Tell me about it! - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/10/database-metrics-matter - -作者：[Katy Farmer][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://opensource.com/users/thekatertot -[b]: https://github.com/lujun9972 diff --git a/sources/tech/20181029 How I organize my knowledge as a Software Engineer.md b/sources/tech/20181029 How I organize my knowledge as a Software Engineer.md deleted file mode 100644 index c11e1c9c38..0000000000 --- a/sources/tech/20181029 How I organize my knowledge as a Software Engineer.md +++ /dev/null @@ -1,119 +0,0 @@ -@flowsnow is translating - - -How I organize my knowledge as a Software Engineer -============================================================ - - -Software Development and Technology in general are areas that evolve at a very fast pace and continuous learning is essential. -Some minutes navigating in the internet, in places like Twitter, Medium, RSS feeds, Hacker News and other specialized sites and communities, are enough to find lots of great pieces of information from articles, case studies, tutorials, code snippets, new applications and much more. - -Saving and organizing all that information can be a daunting task. In this post I will present some tools tools that I use to do it. - -One of the points I consider very important regarding knowledge management is to avoid lock-in in a particular platform. All the tools I use, allow to export your data in standard formats like Markdown and HTML. - -Note that, My workflow is not perfect and I am constantly searching for new tools and ways to optimize it. Also everyone is different, so what works for me might not working well for you. - -### Knowledge base with NotionHQ - -For me, the fundamental piece of Knowledge management is to have some kind of personal Knowledge base / wiki. A place where you can save links, bookmarks, notes etc in an organized manner. - -I use [NotionHQ][7] for that matter. I use it to keep notes on various topics, having lists of resources like great libraries or tutorials grouped by programming language, bookmarking interesting blog posts and tutorials, and much more, not only related to software development but also my personal life. - -What I really like about Notion, is how simple it is to create new content. You write it using Markdown and it is organized as tree. - -Here is my top level pages of my "Development" workspace: - - [][8] - -Notion has some nice other features like integrated spreadsheets / databases and Task boards. - -You will need to subscribe to paid Personal Plan, if you want to use Notion seriously as the free plan is somewhat limited. I think its worth the price. Notion allows to export your entire workspace to Markdown files. The export has some important problems, like loosing the page hierarchy, but hope Notion Team can improve that. - -As a free alternative I would probably use [VuePress][9] or [GitBook][10] to host my own. - -### Save interesting articles with Pocket - -[Pocket][11] is one of my favorite applications ever! With Pocket you can create a reading list of articles from the Internet. -Every time I see an article that looks interesting, I save it to Pocket using its Chrome Extension. Later on, I will read it and If I found it useful enough, I will use the "Archive" function of Pocket to permanently save that article and clean up my Pocket inbox. - -I try to keep the Reading list small enough and keep archiving information that I have dealt with. Pocket allows you to tag articles which will make it simpler to search articles for a particular topic later in time. - -You can also save a copy of the article in Pocket servers in case of the original site disappears, but you will need Pocket Premium for that. - -Pocket also have a "Discover" feature which suggests similar articles based on the articles you have saved. This is a great way to find new content to read. - -### Snippet Management with SnippetStore - -From GitHub, to Stack Overflow answers, to blog posts, its common to find some nice code snippets that you want to save for later. It could be some nice algorithm implementation, an useful script or an example of how to do X in Y language. - -I tried many apps from simple GitHub Gists to [Boostnote][12] until I discovered [SnippetStore][13]. - -SnippetStore is an open source snippet management app. What distinguish SnippetStore from others is its simplicity. You can organize snippets by Language or Tags and you can have multi file snippets. Its not perfect but it gets the job done. Boostnote, for example has more features, but I prefer the simpler way of organizing content of SnippetStore. - -For abbreviations and snippets that I use on a daily basis, I prefer to use my Editor / IDE snippets feature as it is more convenient to use. I use SnippetStore more like a reference of coding examples. - -[Cacher][14] is also an interesting alternative, since it has integrations with many editors, have a cli tool and uses GitHub Gists as backend, but 6$/month for its pro plan, its too much IMO. - -### Managing cheat sheets with DevHints - -[Devhints][15] is a collection of cheat sheets created by Rico Sta. Cruz. Its open source and powered by Jekyll, one of the most popular static site generator. - -The cheat sheets are written in Markdown with some extra formatting goodies like support for columns. - -I really like the looks of the interface and being Markdown makes in incredibly easy to add new content and keep it updated and in version control, unlike cheat sheets in PDF or Image format, that you can find on sites like [Cheatography][16]. - -As it is open source I have created my own fork, removed some cheat sheets that I dont need and add some more. - -I use cheat sheets as reference of how to use some library or programming language or to remember some commands. Its very handy to have a single page, with all the basic syntax of a specific programming language for example. - -I am still experimenting with this but its working great so far. - -### Diigo - -[Diigo][17] allows you to Annotate and Highlight parts of websites. I use it to annotate important information when studying new topics or to save particular paragraphs from articles, Stack Overflow answers or inspirational quotes from Twitter! ;) - -* * * - -And thats it. There might be some overlap in terms of functionality in some of the tools, but like I said in the beginning, this is an always evolving workflow, as I am always experimenting and searching for ways to improve and be more productive. - -What about you? How to you organize your Knowledge?. Please feel free to comment below. - -Thank you for reading. - ------------------------------------------------------------------------- - -作者简介： - -Bruno Paz -Web Engineer. Expert in #PHP and @Symfony Framework. Enthusiast about new technologies. Sports and @FCPorto fan! - --------------------------------------------------------------------------------- - -via: https://dev.to/brpaz/how-do-i-organize-my-knowledge-as-a-software-engineer-4387 - -作者：[ Bruno Paz][a] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) -选题：[oska874](https://github.com/oska874) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:http://brunopaz.net/ -[1]:https://dev.to/brpaz -[2]:http://twitter.com/brunopaz88 -[3]:http://github.com/brpaz -[4]:https://dev.to/t/knowledge -[5]:https://dev.to/t/learning -[6]:https://dev.to/t/development -[7]:https://www.notion.so/ -[8]:https://res.cloudinary.com/practicaldev/image/fetch/s--uMbaRUtu--/c_limit%2Cf_auto%2Cfl_progressive%2Cq_auto%2Cw_880/http://i.imgur.com/kRnuvMV.png -[9]:https://vuepress.vuejs.org/ -[10]:https://www.gitbook.com/?t=1 -[11]:https://getpocket.com/ -[12]:https://boostnote.io/ -[13]:https://github.com/ZeroX-DG/SnippetStore -[14]:https://www.cacher.io/ -[15]:https://devhints.io/ -[16]:https://cheatography.com/ -[17]:https://www.diigo.com/index diff --git a/sources/tech/20181105 5 Minimal Web Browsers for Linux.md b/sources/tech/20181105 5 Minimal Web Browsers for Linux.md new file mode 100644 index 0000000000..1fbc18aeae --- /dev/null +++ b/sources/tech/20181105 5 Minimal Web Browsers for Linux.md @@ -0,0 +1,163 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: subject: (5 Minimal Web Browsers for Linux) +[#]: via: (https://www.linux.com/blog/intro-to-linux/2018/11/5-minimal-web-browsers-linux) +[#]: author: (Jack Wallen https://www.linux.com/users/jlwallen) +[#]: url: ( ) + +5 Minimal Web Browsers for Linux +====== + + +There are so many reasons to enjoy the Linux desktop. One reason I often state up front is the almost unlimited number of choices to be found at almost every conceivable level. From how you interact with the operating system (via a desktop interface), to how daemons run, to what tools you use, you have a multitude of options. + +The same thing goes for web browsers. You can use anything from open source favorites, such as [Firefox][1] and [Chromium][2], or closed sourced industry darlings like [Vivaldi][3] and [Chrome][4]. Those options are full-fledged browsers with every possible bell and whistle you’ll ever need. For some, these feature-rich browsers are perfect for everyday needs. + +There are those, however, who prefer using a web browser without all the frills. In fact, there are many reasons why you might prefer a minimal browser over a standard browser. For some, it’s about browser security, while others look at a web browser as a single-function tool (as opposed to a one-stop shop application). Still others might be running low-powered machines that cannot handle the requirements of, say, Firefox or Chrome. Regardless of the reason, Linux has you covered. + +Let’s take a look at five of the minimal browsers that can be installed on Linux. I’ll be demonstrating these browsers on the Elementary OS platform, but each of these browsers are available to nearly every distribution in the known Linuxverse. Let’s dive in. + +### GNOME Web + +GNOME Web (codename Epiphany, which means [“a usually sudden manifestation or perception of the essential nature or meaning of something”][5]) is the default web browser for Elementary OS, but it can be installed from the standard repositories. (Note, however, that the recommended installation of Epiphany is via Flatpak or Snap). If you choose to install via the standard package manager, issue a command such as sudo apt-get install epiphany-browser -y for successful installation. + +Epiphany uses the WebKit rendering engine, which is the same engine used in Apple’s Safari browser. Couple that rendering engine with the fact that Epiphany has very little in terms of bloat to get in the way, you will enjoy very fast page-rendering speeds. Epiphany development follows strict adherence to the following guidelines: + + * Simplicity - Feature bloat and user interface clutter are considered evil. + + * Standards compliance - No non-standard features will ever be introduced to the codebase. + + * Software freedom - Epiphany will always be released under a license that respects freedom. + + * Human interface - Epiphany follows the [GNOME Human Interface Guidelines][6]. + + * Minimal preferences - Preferences are only added when they make sense and after careful consideration. + + * Target audience - Non-technical users are the primary target audience (which helps to define the types of features that are included). + + + + +GNOME Web is as clean and simple a web browser as you’ll find (Figure 1). + +![GNOME Web][8] + +Figure 1: The GNOME Web browser displaying a minimal amount of preferences for the user. + +[Used with permission][9] + +The GNOME Web manifesto reads: + +A web browser is more than an application: it is a way of thinking, a way of seeing the world. Epiphany's principles are simplicity, standards compliance, and software freedom. + +### Netsurf + +The [Netsurf][10] minimal web browser opens almost faster than you can release the mouse button. Netsurf uses its own layout and rendering engine (designed completely from scratch), which is rather hit and miss in its rendering (Figure 2). + + + +Although you might find Netsurf to suffer from rendering issues on certain sites, understand the Hubbub HTML parser is following the work-in-progress HTML5 specification, so there will be issues popup now and then. To ease those rendering headaches, Netsurf does include HTTPS support, web page thumbnailing, URL completion, scale view, bookmarks, full-screen mode, keyboard shorts, and no particular GUI toolkit requirements. That last bit is important, especially when you switch from one desktop to another. + +For those curious as to the requirements for Netsurf, the browser can run on a machine as slow as a 30Mhz ARM 6 computer with 16MB of RAM. That’s impressive, by today’s standard. + +### QupZilla + +If you’re looking for a minimal browser that uses the Qt Framework and the QtWebKit rendering engine, [QupZilla][11] might be exactly what you’re looking for. QupZilla does include all the standard features and functions you’d expect from a web browser, such as bookmarks, history, sidebar, tabs, RSS feeds, ad blocking, flash blocking, and CA Certificates management. Even with those features, QupZilla still manages to remain a very fast lightweight web browser. Other features include: Fast startup, speed dial homepage, built-in screenshot tool, browser themes, and more. +One feature that should appeal to average users is that QupZilla has a more standard preferences tools than found in many lightweight browsers (Figure 3). So, if going too far outside the lines isn’t your style, but you still want something lighter weight, QupZilla is the browser for you. + +![QupZilla][13] + +Figure 3: The QupZilla preferences tool. + +[Used with permission][9] + +### Otter Browser + +Otter Browser is a free, open source attempt to recreate the closed-source offerings found in the Opera Browser. Otter Browser uses the WebKit rendering engine and has an interface that should be immediately familiar with any user. Although lightweight, Otter Browser does include full-blown features such as: + + * Passwords manager + + * Add-on manager + + * Content blocking + + * Spell checking + + * Customizable GUI + + * URL completion + + * Speed dial (Figure 4) + + * Bookmarks and various related features + + * Mouse gestures + + * User style sheets + + * Built-in Note tool + + +![Otter][15] + +Figure 4: The Otter Browser Speed Dial tab. + +[Used with permission][9] + +Otter Browser can be run on nearly any Linux distribution from an [AppImage][16], so there’s no installation required. Just download the AppImage file, give the file executable permissions (with the command chmod u+x otter-browser-*.AppImage), and then launch the app with the command ./otter-browser*.AppImage. + +Otter Browser does an outstanding job of rendering websites and could function as your go-to minimal browser with ease. + +### Lynx + +Let’s get really minimal. When I first started using Linux, back in ‘97, one of the web browsers I often turned to was a text-only take on the app called [Lynx][17]. It should come as no surprise that Lynx is still around and available for installation from the standard repositories. As you might expect, Lynx works from the terminal window and doesn’t display pretty pictures or render much in the way of advanced features (Figure 5). In fact, Lynx is as bare-bones a browser as you will find available. Because of how bare-bones this web browser is, it’s not recommended for everyone. But if you happen to have a gui-less web server and you have a need to be able to read the occasional website, Lynx can be a real lifesaver. + +![Lynx][19] + +Figure 5: The Lynx browser rendering the Linux.com page. + +[Used with permission][9] + +I have also found Lynx an invaluable tool when troubleshooting certain aspects of a website (or if some feature on a website is preventing me from viewing the content in a regular browser). Another good reason to use Lynx is when you only want to view the content (and not the extraneous elements). + +### Plenty More Where This Came From + +There are plenty more minimal browsers than this. But the list presented here should get you started down the path of minimalism. One (or more) of these browsers are sure to fill that need, whether you’re running it on a low-powered machine or not. + +Learn more about Linux through the free ["Introduction to Linux" ][20]course from The Linux Foundation and edX. + +-------------------------------------------------------------------------------- + +via: https://www.linux.com/blog/intro-to-linux/2018/11/5-minimal-web-browsers-linux + +作者：[Jack Wallen][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.linux.com/users/jlwallen +[b]: https://github.com/lujun9972 +[1]: https://www.mozilla.org/en-US/firefox/new/ +[2]: https://www.chromium.org/ +[3]: https://vivaldi.com/ +[4]: https://www.google.com/chrome/ +[5]: https://www.merriam-webster.com/dictionary/epiphany +[6]: https://developer.gnome.org/hig/stable/ +[7]: /files/images/minimalbrowsers1jpg +[8]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/minimalbrowsers_1.jpg?itok=Q7wZLF8B (GNOME Web) +[9]: /licenses/category/used-permission +[10]: https://www.netsurf-browser.org/ +[11]: https://qupzilla.com/ +[12]: /files/images/minimalbrowsers3jpg +[13]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/minimalbrowsers_3.jpg?itok=O8iMALWO (QupZilla) +[14]: /files/images/minimalbrowsers4jpg +[15]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/minimalbrowsers_4.jpg?itok=5bCa0z-e (Otter) +[16]: https://sourceforge.net/projects/otter-browser/files/ +[17]: https://lynx.browser.org/ +[18]: /files/images/minimalbrowsers5jpg +[19]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/minimalbrowsers_5.jpg?itok=p_Lmiuxh (Lynx) +[20]: https://training.linuxfoundation.org/linux-courses/system-administration-training/introduction-to-linux diff --git a/sources/tech/20181105 How to manage storage on Linux with LVM.md b/sources/tech/20181105 How to manage storage on Linux with LVM.md index 36cc8d47a0..9c0ee685d6 100644 --- a/sources/tech/20181105 How to manage storage on Linux with LVM.md +++ b/sources/tech/20181105 How to manage storage on Linux with LVM.md @@ -1,3 +1,4 @@ +[zianglei translating] How to manage storage on Linux with LVM ====== Create, expand, and encrypt storage pools as needed with the Linux LVM utilities. diff --git a/sources/tech/20181105 Revisiting the Unix philosophy in 2018.md b/sources/tech/20181105 Revisiting the Unix philosophy in 2018.md deleted file mode 100644 index 1088f0de5b..0000000000 --- a/sources/tech/20181105 Revisiting the Unix philosophy in 2018.md +++ /dev/null @@ -1,106 +0,0 @@ -Translating by Jamkr - -Revisiting the Unix philosophy in 2018 -====== -The old strategy of building small, focused applications is new again in the modern microservices environment. - - -In 1984, Rob Pike and Brian W. Kernighan published an article called "[Program Design in the Unix Environment][1]" in the AT&T Bell Laboratories Technical Journal, in which they argued the Unix philosophy, using the example of BSD's **cat -v** implementation. In a nutshell that philosophy is: Build small, focused programs—in whatever language—that do only one thing but do this thing well, communicate via **stdin** / **stdout** , and are connected through pipes. - -Sound familiar? - -Yeah, I thought so. That's pretty much the [definition of microservices][2] offered by James Lewis and Martin Fowler: - -> In short, the microservice architectural style is an approach to developing a single application as a suite of small services, each running in its own process and communicating with lightweight mechanisms, often an HTTP resource API. - -While one *nix program or one microservice may be very limited or not even very interesting on its own, it's the combination of such independently working units that reveals their true benefit and, therefore, their power. - -### *nix vs. microservices - -The following table compares programs (such as **cat** or **lsof** ) in a *nix environment against programs in a microservices environment. - -| | *nix | Microservices | -| ----------------------------------- | -------------------------- | ----------------------------------- | -| Unit of execution | program using stdin/stdout | service with HTTP or gRPC API | -| Data flow | Pipes | ? | -| Configuration & parameterization | Command-line arguments, | | -| environment variables, config files | JSON/YAML docs | | -| Discovery | Package manager, man, make | DNS, environment variables, OpenAPI | - -Let's explore each line in slightly greater detail. - -#### Unit of execution - -**stdin** and writes output to **stdout**. A microservices setup deals with a service that exposes one or more communication interfaces, such as HTTP or gRPC APIs. In both cases, you'll find stateless examples (essentially a purely functional behavior) and stateful examples, where, in addition to the input, some internal (persisted) state decides what happens. - -#### Data flow - -The unit of execution in *nix (such as Linux) is an executable file (binary or interpreted script) that, ideally, reads input fromand writes output to. A microservices setup deals with a service that exposes one or more communication interfaces, such as HTTP or gRPC APIs. In both cases, you'll find stateless examples (essentially a purely functional behavior) and stateful examples, where, in addition to the input, some internal (persisted) state decides what happens. - -Traditionally, *nix programs could communicate via pipes. In other words, thanks to [Doug McIlroy][3], you don't need to create temporary files to pass around and each can process virtually endless streams of data between processes. To my knowledge, there is nothing comparable to a pipe standardized in microservices, besides my little [Apache Kafka-based experiment from 2017][4]. - -#### Configuration and parameterization - -How do you configure a program or service—either on a permanent or a by-call basis? Well, with *nix programs you essentially have three options: command-line arguments, environment variables, or full-blown config files. In microservices, you typically deal with YAML (or even worse, JSON) documents, defining the layout and configuration of a single microservice as well as dependencies and communication, storage, and runtime settings. Examples include [Kubernetes resource definitions][5], [Nomad job specifications][6], or [Docker Compose][7] files. These may or may not be parameterized; that is, either you have some templating language, such as [Helm][8] in Kubernetes, or you find yourself doing an awful lot of **sed -i** commands. - -#### Discovery - -How do you know what programs or services are available and how they are supposed to be used? Well, in *nix, you typically have a package manager as well as good old man; between them, they should be able to answer all the questions you might have. In a microservices setup, there's a bit more automation in finding a service. In addition to bespoke approaches like [Airbnb's SmartStack][9] or [Netflix's Eureka][10], there usually are environment variable-based or DNS-based [approaches][11] that allow you to discover services dynamically. Equally important, [OpenAPI][12] provides a de-facto standard for HTTP API documentation and design, and [gRPC][13] does the same for more tightly coupled high-performance cases. Last but not least, take developer experience (DX) into account, starting with writing good [Makefiles][14] and ending with writing your docs with (or in?) [**style**][15]. - -### Pros and cons - -Both *nix and microservices offer a number of challenges and opportunities - -#### Composability - -It's hard to design something that has a clear, sharp focus and can also play well with others. It's even harder to get it right across different versions and to introduce respective error case handling capabilities. In microservices, this could mean retry logic and timeouts—maybe it's a better option to outsource these features into a service mesh? It's hard, but if you get it right, its reusability can be enormous. - -#### Observability - -In a monolith (in 2018) or a big program that tries to do it all (in 1984), it's rather straightforward to find the culprit when things go south. But, in a - -``` -yes | tr \\n x | head -c 450m | grep n -``` - -or a request path in a microservices setup that involves, say, 20 services, how do you even start to figure out which one is behaving badly? Luckily we have standards, notably [OpenCensus][16] and [OpenTracing][17]. Observability still might be the biggest single blocker if you are looking to move to microservices. - -#### Global state - -While it may not be such a big issue for *nix programs, in microservices, global state remains something of a discussion. Namely, how to make sure the local (persistent) state is managed effectively and how to make the global state consistent with as little effort as possible. - -### Wrapping up - -In the end, the question remains: Are you using the right tool for a given task? That is, in the same way a specialized *nix program implementing a range of functions might be the better choice for certain use cases or phases, it might be that a monolith [is the best option][18] for your organization or workload. Regardless, I hope this article helps you see the many, strong parallels between the Unix philosophy and microservices—maybe we can learn something from the former to benefit the latter. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/11/revisiting-unix-philosophy-2018 - -作者：[Michael Hausenblas][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://opensource.com/users/mhausenblas -[b]: https://github.com/lujun9972 -[1]: http://harmful.cat-v.org/cat-v/ -[2]: https://martinfowler.com/articles/microservices.html -[3]: https://en.wikipedia.org/wiki/Douglas_McIlroy -[4]: https://speakerdeck.com/mhausenblas/distributed-named-pipes-and-other-inter-services-communication -[5]: http://kubernetesbyexample.com/ -[6]: https://www.nomadproject.io/docs/job-specification/index.html -[7]: https://docs.docker.com/compose/overview/ -[8]: https://helm.sh/ -[9]: https://github.com/airbnb/smartstack-cookbook -[10]: https://github.com/Netflix/eureka -[11]: https://kubernetes.io/docs/concepts/services-networking/service/#discovering-services -[12]: https://www.openapis.org/ -[13]: https://grpc.io/ -[14]: https://suva.sh/posts/well-documented-makefiles/ -[15]: https://www.linux.com/news/improve-your-writing-gnu-style-checkers -[16]: https://opencensus.io/ -[17]: https://opentracing.io/ -[18]: https://robertnorthard.com/devops-days-well-architected-monoliths-are-okay/ diff --git a/sources/tech/20181106 How To Check The List Of Packages Installed From Particular Repository.md b/sources/tech/20181106 How To Check The List Of Packages Installed From Particular Repository.md new file mode 100644 index 0000000000..81111b465c --- /dev/null +++ b/sources/tech/20181106 How To Check The List Of Packages Installed From Particular Repository.md @@ -0,0 +1,342 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: subject: (How To Check The List Of Packages Installed From Particular Repository?) +[#]: via: (https://www.2daygeek.com/how-to-check-the-list-of-packages-installed-from-particular-repository/) +[#]: author: (Prakash Subramanian https://www.2daygeek.com/author/prakash/) +[#]: url: ( ) + +How To Check The List Of Packages Installed From Particular Repository? +====== + +If you would like to check the list of package installed from particular repository then you are in the right place to get it done. + +Why we need this detail? It may helps you to isolate the installed packages list based on the repository. + +Like, it’s coming from distribution official repository or these are coming from PPA or these are coming from other resources, etc., + +You may want to know what are the packages came from third party repositories to keep eye on those to avoid any damages on your system. + +So many third party repositories and PPAs are available for Linux. These repositories are included set of packages which is not available in distribution repository due to some limitation. + +It helps administrator to easily install some of the important packages which is not available in the distribution official repository. Installing third party repository on production system is not advisable as this may not properly maintained by the repository maintainer due to many reasons. + +So, you have to decide whether you want to install or not. I can say, we can believe some of the third party repositories which is well maintained and suggested by Linux distributions like [EPEL repository][1], Copr (Cool Other Package Repo), etc,. + +If you would like to see the list of package was installed from the corresponding repo, use the following commands based on your distributions. + +[List of Major repositories][2] and it’s details are below. + + * **`CentOS:`** [EPEL][1], [ELRepo][3], etc is [CentOS Community Approved Repositories][4]. + * **`Fedora:`** [RPMfusion repo][5] is commonly used by most of the [Fedora][6] users. + * **`ArchLinux:`** ArchLinux community repository contains packages that have been adopted by Trusted Users from the Arch User Repository. + * **`openSUSE:`** [Packman repo][7] offers various additional packages for openSUSE, especially but not limited to multimedia related applications and libraries that are on the openSUSE Build Service application blacklist. It’s the largest external repository of openSUSE packages. + * **`Ubuntu:`** Personal Package Archives (PPAs) are a kind of repository. Developers create them in order to distribute their software. You can find this information on the PPA’s Launchpad page. Also, you can enable Cananical partners repositories. + + + +### What Is Repository? + +A software repository is a central place which stores the software packages for the particular application. + +All the Linux distributions are maintaining their own repositories and they allow users to retrieve and install packages on their machine. + +Each vendor offered a unique package management tool to manage their repositories such as search, install, update, upgrade, remove, etc. + +Most of the Linux distributions comes as freeware except RHEL and SUSE. To access their repositories you need to buy a subscriptions. + +### How To Check The List Of Packages Installed From Particular Repository on RHEL/CentOS Systems? + +This can be done in multiple ways. Here we will be giving you all the possible options and you can choose which one is best for you. + +### Method-1: Using Yum Command + +RHEL & CentOS systems are using RPM packages hence we can use the [Yum Package Manager][8] to get this information. + +YUM stands for Yellowdog Updater, Modified is an open-source command-line front-end package-management utility for RPM based systems such as Red Hat Enterprise Linux (RHEL) and CentOS. + +Yum is the primary tool for getting, installing, deleting, querying, and managing RPM packages from distribution repositories, as well as other third-party repositories. + +``` +[[email protected] ~]# yum list installed | grep @epel +apachetop.x86_64 0.15.6-1.el7 @epel +aria2.x86_64 1.18.10-2.el7.1 @epel +atop.x86_64 2.3.0-8.el7 @epel +axel.x86_64 2.4-9.el7 @epel +epel-release.noarch 7-11 @epel +lighttpd.x86_64 1.4.50-1.el7 @epel +``` + +Alternatively, you can use the yum command with other option to get the same details like above. + +``` +# yum repo-pkgs epel list installed +Loaded plugins: fastestmirror +Loading mirror speeds from cached hostfile + * epel: epel.mirror.constant.com +Installed Packages +apachetop.x86_64 0.15.6-1.el7 @epel +aria2.x86_64 1.18.10-2.el7.1 @epel +atop.x86_64 2.3.0-8.el7 @epel +axel.x86_64 2.4-9.el7 @epel +epel-release.noarch 7-11 @epel +lighttpd.x86_64 1.4.50-1.el7 @epel +``` + +### Method-2: Using Yumdb Command + +Yumdb info provides information similar to yum info but additionally it provides package checksum data, type, user info (who installed the package). Since yum 3.2.26 yum has started storing additional information outside of the rpmdatabase (where user indicates it was installed by the user, and dep means it was brought in as a dependency). + +``` +# yumdb search from_repo epel* |egrep -v '(from_repo|^$)' +Loaded plugins: fastestmirror +apachetop-0.15.6-1.el7.x86_64 +aria2-1.18.10-2.el7.1.x86_64 +atop-2.3.0-8.el7.x86_64 +axel-2.4-9.el7.x86_64 +epel-release-7-11.noarch +lighttpd-1.4.50-1.el7.x86_64 +``` + +### Method-3: Using Repoquery Command + +repoquery is a program for querying information from YUM repositories similarly to rpm queries. + +``` +# repoquery -a --installed --qf "%{ui_from_repo} %{name}" | grep '^@epel' +@epel apachetop +@epel aria2 +@epel atop +@epel axel +@epel epel-release +@epel lighttpd +``` + +### How To Check The List Of Packages Installed From Particular Repository on Fedora System? + +DNF stands for Dandified yum. We can tell DNF, the next generation of yum package manager (Fork of Yum) using hawkey/libsolv library for back-end. Aleš Kozumplík started working on DNF since Fedora 18 and its implemented/launched in Fedora 22 finally. + +[Dnf command][9] is used to install, update, search & remove packages on Fedora 22 and later system. It automatically resolve dependencies and make it smooth package installation without any trouble. + +``` +# dnf list installed | grep @updates +NetworkManager.x86_64 1:1.12.4-2.fc29 @updates +NetworkManager-adsl.x86_64 1:1.12.4-2.fc29 @updates +NetworkManager-bluetooth.x86_64 1:1.12.4-2.fc29 @updates +NetworkManager-libnm.x86_64 1:1.12.4-2.fc29 @updates +NetworkManager-libreswan.x86_64 1.2.10-1.fc29 @updates +NetworkManager-libreswan-gnome.x86_64 1.2.10-1.fc29 @updates +NetworkManager-openvpn.x86_64 1:1.8.8-1.fc29 @updates +NetworkManager-openvpn-gnome.x86_64 1:1.8.8-1.fc29 @updates +NetworkManager-ovs.x86_64 1:1.12.4-2.fc29 @updates +NetworkManager-ppp.x86_64 1:1.12.4-2.fc29 @updates +. +. +``` + +Alternatively, you can use the dnf command with other option to get the same details like above. + +``` +# dnf repo-pkgs updates list installed +Installed Packages +NetworkManager.x86_64 1:1.12.4-2.fc29 @updates +NetworkManager-adsl.x86_64 1:1.12.4-2.fc29 @updates +NetworkManager-bluetooth.x86_64 1:1.12.4-2.fc29 @updates +NetworkManager-libnm.x86_64 1:1.12.4-2.fc29 @updates +NetworkManager-libreswan.x86_64 1.2.10-1.fc29 @updates +NetworkManager-libreswan-gnome.x86_64 1.2.10-1.fc29 @updates +NetworkManager-openvpn.x86_64 1:1.8.8-1.fc29 @updates +NetworkManager-openvpn-gnome.x86_64 1:1.8.8-1.fc29 @updates +NetworkManager-ovs.x86_64 1:1.12.4-2.fc29 @updates +. +. +``` + +### How To Check The List Of Packages Installed From Particular Repository on openSUSE System? + +Zypper is a command line package manager which makes use of libzypp. [Zypper command][10] provides functions like repository access, dependency solving, package installation, etc. + +``` +zypper search -ir "Update Repository (Non-Oss)" +Loading repository data... +Reading installed packages... + +S | Name | Summary | Type +---+----------------------------+---------------------------------------------------+-------- +i | gstreamer-0_10-fluendo-mp3 | GStreamer plug-in from Fluendo for MP3 support | package +i+ | openSUSE-2016-615 | Test-update for openSUSE Leap 42.2 Non Free | patch +i+ | openSUSE-2017-724 | Security update for unrar | patch +i | unrar | A program to extract, test, and view RAR archives | package +``` + +Alternatively, we can use repo id instead of repo name. + +``` +zypper search -ir 2 +Loading repository data... +Reading installed packages... + +S | Name | Summary | Type +---+----------------------------+---------------------------------------------------+-------- +i | gstreamer-0_10-fluendo-mp3 | GStreamer plug-in from Fluendo for MP3 support | package +i+ | openSUSE-2016-615 | Test-update for openSUSE Leap 42.2 Non Free | patch +i+ | openSUSE-2017-724 | Security update for unrar | patch +i | unrar | A program to extract, test, and view RAR archives | package +``` + +### How To Check The List Of Packages Installed From Particular Repository on ArchLinux System? + +[Pacman command][11] stands for package manager utility. pacman is a simple command-line utility to install, build, remove and manage Arch Linux packages. Pacman uses libalpm (Arch Linux Package Management (ALPM) library) as a back-end to perform all the actions. + +``` +$ paclist community +acpi 1.7-2 +acpid 2.0.30-1 +adapta-maia-theme 3.94.0.149-1 +android-tools 9.0.0_r3-1 +blueman 2.0.6-1 +brotli 1.0.7-1 +. +. +ufw 0.35-5 +unace 2.5-10 +usb_modeswitch 2.5.2-1 +viewnior 1.7-1 +wallpapers-2018 1.0-1 +xcursor-breeze 5.11.5-1 +xcursor-simpleandsoft 0.2-8 +xcursor-vanilla-dmz-aa 0.4.5-1 +xfce4-whiskermenu-plugin-gtk3 2.3.0-1 +zeromq 4.2.5-1 +``` + +### How To Check The List Of Packages Installed From Particular Repository on Debian Based Systems? + +For Debian based systems, it can be done using grep command. + +If you want to know the list of installed repositories on your system, use the following command. + +``` +$ ls -lh /var/lib/apt/lists/ | uniq +total 370M +-rw-r--r-- 1 root root 10K Oct 26 10:53 archive.canonical.com_ubuntu_dists_bionic_InRelease +-rw-r--r-- 1 root root 6.4K Oct 26 10:53 archive.canonical.com_ubuntu_dists_bionic_partner_binary-amd64_Packages +-rw-r--r-- 1 root root 6.4K Oct 26 10:53 archive.canonical.com_ubuntu_dists_bionic_partner_binary-i386_Packages +-rw-r--r-- 1 root root 3.2K Jun 12 21:19 archive.canonical.com_ubuntu_dists_bionic_partner_i18n_Translation-en +drwxr-xr-x 2 _apt root 4.0K Jul 25 08:44 auxfiles +-rw-r--r-- 1 root root 3.7K Oct 16 15:13 download.virtualbox.org_virtualbox_debian_dists_bionic_contrib_binary-amd64_Packages +-rw-r--r-- 1 root root 7.2K Oct 16 15:13 download.virtualbox.org_virtualbox_debian_dists_bionic_contrib_Contents-amd64.lz4 +-rw-r--r-- 1 root root 4.4K Oct 16 15:13 download.virtualbox.org_virtualbox_debian_dists_bionic_InRelease +-rw-r--r-- 1 root root 34 Mar 19 2018 download.virtualbox.org_virtualbox_debian_dists_bionic_non-free_Contents-amd64.lz4 +-rw-r--r-- 1 root root 6.4K Sep 21 09:42 in.archive.ubuntu.com_ubuntu_dists_bionic-backports_Contents-amd64.lz4 +-rw-r--r-- 1 root root 6.4K Sep 21 09:42 in.archive.ubuntu.com_ubuntu_dists_bionic-backports_Contents-i386.lz4 +-rw-r--r-- 1 root root 73K Nov 6 11:16 in.archive.ubuntu.com_ubuntu_dists_bionic-backports_InRelease +. +. +-rw-r--r-- 1 root root 29 May 11 06:39 security.ubuntu.com_ubuntu_dists_bionic-security_main_dep11_icons-64x64.tar.gz +-rw-r--r-- 1 root root 747K Nov 5 23:57 security.ubuntu.com_ubuntu_dists_bionic-security_main_i18n_Translation-en +-rw-r--r-- 1 root root 2.8K Oct 9 22:37 security.ubuntu.com_ubuntu_dists_bionic-security_multiverse_binary-amd64_Packages +-rw-r--r-- 1 root root 3.7K Oct 9 22:37 security.ubuntu.com_ubuntu_dists_bionic-security_multiverse_binary-i386_Packages +-rw-r--r-- 1 root root 1.8K Jul 24 23:06 security.ubuntu.com_ubuntu_dists_bionic-security_multiverse_i18n_Translation-en +-rw-r--r-- 1 root root 519K Nov 5 20:12 security.ubuntu.com_ubuntu_dists_bionic-security_universe_binary-amd64_Packages +-rw-r--r-- 1 root root 517K Nov 5 20:12 security.ubuntu.com_ubuntu_dists_bionic-security_universe_binary-i386_Packages +-rw-r--r-- 1 root root 11K Nov 6 05:36 security.ubuntu.com_ubuntu_dists_bionic-security_universe_dep11_Components-amd64.yml.gz +-rw-r--r-- 1 root root 8.9K Nov 6 05:36 security.ubuntu.com_ubuntu_dists_bionic-security_universe_dep11_icons-48x48.tar.gz +-rw-r--r-- 1 root root 16K Nov 6 05:36 security.ubuntu.com_ubuntu_dists_bionic-security_universe_dep11_icons-64x64.tar.gz +-rw-r--r-- 1 root root 315K Nov 5 20:12 security.ubuntu.com_ubuntu_dists_bionic-security_universe_i18n_Translation-en +``` + +To get the list of installed packages from the `security.ubuntu.com` repository. + +``` +$ grep Package /var/lib/apt/lists/security.ubuntu.com_*_Packages | awk '{print $2;}' +amd64-microcode +apache2 +apache2-bin +apache2-data +apache2-dbg +apache2-dev +. +. +znc +znc-dev +znc-perl +znc-python +znc-tcl +zsh-static +zziplib-bin +``` + +The security repository containing multiple branches (main, multiverse and universe) and if you would like to list out the installed packages from the particular repository `universe` then use the following format. + +``` +$ grep Package /var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_bionic-security_universe*_Packages | awk '{print $2;}' +ant +ant-doc +ant-optional +apache2-suexec-custom +apache2-suexec-pristine +apparmor-easyprof +apport-kde +apport-noui +apport-valgrind +apt-transport-https +. +. +xul-ext-gdata-provider +xul-ext-lightning +xvfb +znc +znc-dev +znc-perl +znc-python +znc-tcl +zsh-static +zziplib-bin +``` + +one more example for `ppa.launchpad.net` repository. + +``` +$ grep Package /var/lib/apt/lists/ppa.launchpad.net_*_Packages | awk '{print $2;}' +notepadqq +notepadqq-gtk +notepadqq-common +notepadqq +notepadqq-gtk +notepadqq-common +numix-gtk-theme +numix-icon-theme +numix-icon-theme-circle +numix-icon-theme-square +numix-gtk-theme +numix-icon-theme +numix-icon-theme-circle +numix-icon-theme-square +``` + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/how-to-check-the-list-of-packages-installed-from-particular-repository/ + +作者：[Prakash Subramanian][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.2daygeek.com/author/prakash/ +[b]: https://github.com/lujun9972 +[1]: https://www.2daygeek.com/install-enable-epel-repository-on-rhel-centos-scientific-linux-oracle-linux/ +[2]: https://www.2daygeek.com/category/repository/ +[3]: https://www.2daygeek.com/install-enable-elrepo-on-rhel-centos-scientific-linux/ +[4]: https://www.2daygeek.com/additional-yum-repositories-for-centos-rhel-fedora-systems/ +[5]: https://www.2daygeek.com/install-enable-rpm-fusion-repository-on-centos-fedora-rhel/ +[6]: https://fedoraproject.org/wiki/Third_party_repositories +[7]: https://www.2daygeek.com/install-enable-packman-repository-on-opensuse-leap/ +[8]: https://www.2daygeek.com/yum-command-examples-manage-packages-rhel-centos-systems/ +[9]: https://www.2daygeek.com/dnf-command-examples-manage-packages-fedora-system/ +[10]: https://www.2daygeek.com/zypper-command-examples-manage-packages-opensuse-system/ +[11]: https://www.2daygeek.com/pacman-command-examples-manage-packages-arch-linux-system/ diff --git a/sources/tech/20181106 How to partition and format a drive on Linux.md b/sources/tech/20181106 How to partition and format a drive on Linux.md deleted file mode 100644 index 7b5d7980b0..0000000000 --- a/sources/tech/20181106 How to partition and format a drive on Linux.md +++ /dev/null @@ -1,216 +0,0 @@ -How to partition and format a drive on Linux -====== -Everything you wanted to know about setting up storage but were afraid to ask. - - -On most computer systems, Linux or otherwise, when you plug a USB thumb drive in, you're alerted that the drive exists. If the drive is already partitioned and formatted to your liking, you just need your computer to list the drive somewhere in your file manager window or on your desktop. It's a simple requirement and one that the computer generally fulfills. - -Sometimes, however, a drive isn't set up the way you want. For those times, you need to know how to find and prepare a storage device connected to your machine. - -### What are block devices? - -A hard drive is generically referred to as a "block device" because hard drives read and write data in fixed-size blocks. This differentiates a hard drive from anything else you might plug into your computer, like a printer, gamepad, microphone, or camera. The easy way to list the block devices attached to your Linux system is to use the **lsblk** (list block devices) command: - -``` -$ lsblk -NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT -sda 8:0 0 238.5G 0 disk -├─sda1 8:1 0 1G 0 part /boot -└─sda2 8:2 0 237.5G 0 part - └─luks-e2bb...e9f8 253:0 0 237.5G 0 crypt - ├─fedora-root 253:1 0 50G 0 lvm / - ├─fedora-swap 253:2 0 5.8G 0 lvm [SWAP] - └─fedora-home 253:3 0 181.7G 0 lvm /home -sdb 8:16 1 14.6G 0 disk -└─sdb1 8:17 1 14.6G 0 part -``` - -The device identifiers are listed in the left column, each beginning with **sd** , and ending with a letter, starting with **a**. Each partition of each drive is assigned a number, starting with **1**. For example, the second partition of the first drive is **sda2**. If you're not sure what a partition is, that's OK—just keep reading. - -The **lsblk** command is nondestructive and used only for probing, so you can run it without any fear of ruining data on a drive. - -### Testing with dmesg - -If in doubt, you can test device label assignments by looking at the tail end of the **dmesg** command, which displays recent system log entries including kernel events (such as attaching and detaching a drive). For instance, if you want to make sure a thumb drive is really **/dev/sdc** , plug the drive into your computer and run this **dmesg** command: - -``` -$ sudo dmesg | tail -``` - -The most recent drive listed is the one you just plugged in. If you unplug it and run that command again, you'll see the device has been removed. If you plug it in again and run the command, the device will be there. In other words, you can monitor the kernel's awareness of your drive. - -### Understanding filesystems - -If all you need is the device label, your work is done. But if your goal is to create a usable drive, you must give the drive a filesystem. - -If you're not sure what a filesystem is, it's probably easier to understand the concept by learning what happens when you have no filesystem at all. If you have a spare drive that has no important data on it whatsoever, you can follow along with this example. Otherwise, do not attempt this exercise, because it will DEFINITELY ERASE DATA, by design. - -It is possible to utilize a drive without a filesystem. Once you have definitely, correctly identified a drive, and you have absolutely verified there is nothing important on it, plug it into your computer—but do not mount it. If it auto-mounts, then unmount it manually. - -``` -$ su - -# umount /dev/sdx{,1} -``` - -To safeguard against disastrous copy-paste errors, these examples use the unlikely **sdx** label for the drive. - -Now that the drive is unmounted, try this: - -``` -# echo 'hello world' > /dev/sdx -``` - -You have just written data to the block device without it being mounted on your system or having a filesystem. - -To retrieve the data you just wrote, you can view the raw data on the drive: - -``` -# head -n 1 /dev/sdx -hello world -``` - -That seemed to work pretty well, but imagine that the phrase "hello world" is one file. If you want to write a new "file" using this method, you must: - - 1. Know there's already an existing "file" on line 1 - 2. Know that the existing "file" takes up only 1 line - 3. Derive a way to append new data, or else rewrite line 1 while writing line 2 - - - -For example: - -``` -# echo 'hello world -> this is a second file' >> /dev/sdx -``` - -To get the first file, nothing changes. - -``` -# head -n 1 /dev/sdx -hello world -``` - -But it's more complex to get the second file. - -``` -# head -n 2 /dev/sdx | tail -n 1 -this is a second file -``` - -Obviously, this method of writing and reading data is not practical, so developers have created systems to keep track of what constitutes a file, where one file begins and ends, and so on. - -Most filesystems require a partition. - -### Creating partitions - -A partition on a hard drive is a sort of boundary on the device telling each filesystem what space it can occupy. For instance, if you have a 4GB thumb drive, you can have a partition on that device taking up the entire drive (4GB), two partitions that each take 2GB (or 1 and 3, if you prefer), three of some variation of sizes, and so on. The combinations are nearly endless. - -Assuming your drive is 4GB, you can create one big partition from a terminal with the GNU **parted** command: - -``` -# parted /dev/sdx --align opt mklabel msdos 0 4G -``` - -This command specifies the device path first, as required by **parted**. - -The **\--align** option lets **parted** find the partition's optimal starting and stopping point. - -The **mklabel** command creates a partition table (called a disk label) on the device. This example uses the **msdos** label because it's a very compatible and popular label, although **gpt** is becoming more common. - -The desired start and end points of the partition are defined last. Since the **\--align opt** flag is used, **parted** will adjust the size as needed to optimize drive performance, but these numbers serve as a guideline. - -Next, create the actual partition. If your start and end choices are not optimal, **parted** warns you and asks if you want to make adjustments. - -``` -# parted /dev/sdx -a opt mkpart primary 0 4G - -Warning: The resulting partition is not properly aligned for best performance: 1s % 2048s != 0s -Ignore/Cancel? C -# parted /dev/sdx -a opt mkpart primary 2048s 4G -``` - -If you run **lsblk** again (you may have to unplug the drive and plug it back in), you'll see that your drive now has one partition on it. - -### Manually creating a filesystem - -There are many filesystems available. Some are free and open source, while others are not. Some companies decline to support open source filesystems, so their users can't read from open filesystems, while open source users can't read from closed ones without reverse-engineering them. - -This disconnect notwithstanding, there are lots of filesystems you can use, and the one you choose depends on the drive's purpose. If you want a drive to be compatible across many systems, then your only choice right now is the exFAT filesystem. Microsoft has not submitted exFAT code to any open source kernel, so you may have to install exFAT support with your package manager, but support for exFAT is included in both Windows and MacOS. - -Once you have exFAT support installed, you can create an exFAT filesystem on your drive in the partition you created. - -``` -# mkfs.exfat -n myExFatDrive /dev/sdx1 -``` - -Now your drive is readable and writable by closed systems and by open source systems utilizing additional (and as-yet unsanctioned by Microsoft) kernel modules. - -A common filesystem native to Linux is [ext4][1]. It's arguably a troublesome filesystem for portable drives since it retains user permissions, which are often different from one computer to another, but it's generally a reliable and flexible filesystem. As long as you're comfortable managing permissions, ext4 is a great, journaled filesystem for portable drives. - -``` -# mkfs.ext4 -L myExt4Drive /dev/sdx1 -``` - -Unplug your drive and plug it back in. For ext4 portable drives, use **sudo** to create a directory and grant permission to that directory to a user and a group common across your systems. If you're not sure what user and group to use, you can either modify read/write permissions with **sudo** or root on the system that's having trouble with the drive. - -### Using desktop tools - -It's great to know how to deal with drives with nothing but a Linux shell standing between you and the block device, but sometimes you just want to get a drive ready to use without so much insightful probing. Excellent tools from both the GNOME and KDE developers can make your drive prep easy. - -[GNOME Disks][2] and [KDE Partition Manager][3] are graphical interfaces providing an all-in-one solution for everything this article has explained so far. Launch either of these applications to see a list of attached devices (in the left column), create or resize partitions, and create a filesystem. - -![KDE Partition Manager][5] - -KDE Partition Manager - -The GNOME version is, predictably, simpler than the KDE version, so I'll demo the more complex one—it's easy to figure out GNOME Disks if that's what you have handy. - -Launch KDE Partition Manager and enter your root password. - -From the left column, select the disk you want to format. If your drive isn't listed, make sure it's plugged in, then select **Tools** > **Refresh devices** (or **F5** on your keyboard). - -Don't continue unless you're ready to destroy the drive's existing partition table. With the drive selected, click **New Partition Table** in the top toolbar. You'll be prompted to select the label you want to give the partition table: either **gpt** or **msdos**. The former is more flexible and can handle larger drives, while the latter is, like many Microsoft technologies, the de-facto standard by force of market share. - -Now that you have a fresh partition table, right-click on your device in the right panel and select **New** to create a new partition. Follow the prompts to set the type and size of your partition. This action combines the partitioning step with creating a filesystem. - -![Create a new partition][7] - -Creating a new partition - -To apply your changes to the drive, click the **Apply** button in the top-left corner of the window. - -### Hard drives, easy drives - -Dealing with hard drives is easy on Linux, and it's even easier if you understand the language of hard drives. Since switching to Linux, I've been better equipped to prepare drives in whatever way I want them to work for me. It's also been easier for me to recover lost data because of the transparency Linux provides when dealing with storage. - -Here are a final few tips, if you want to experiment and learn more about hard drives: - - 1. Back up your data, and not just the data on the drive you're experimenting with. All it takes is one wrong move to destroy the partition of an important drive (which is a great way to learn about recreating lost partitions, but not much fun). - 2. Verify and then re-verify that the drive you are targeting is the correct drive. I frequently use **lsblk** to make sure I haven't moved drives around on myself. (It's easy to remove two drives from two separate USB ports, then mindlessly reattach them in a different order, causing them to get new drive labels.) - 3. Take the time to "destroy" a test drive and see if you can recover the data. It's a good learning experience to recreate a partition table or try to get data back after a filesystem has been removed. - - - -For extra fun, if you have a closed operating system lying around, try getting an open source filesystem working on it. There are a few projects working toward this kind of compatibility, and trying to get them working in a stable and reliable way is a good weekend project. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/11/partition-format-drive-linux - -作者：[Seth Kenlon][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://opensource.com/users/seth -[b]: https://github.com/lujun9972 -[1]: https://opensource.com/article/17/5/introduction-ext4-filesystem -[2]: https://wiki.gnome.org/Apps/Disks -[3]: https://www.kde.org/applications/system/kdepartitionmanager/ -[4]: /file/413586 -[5]: https://opensource.com/sites/default/files/uploads/blockdevices_kdepartition.jpeg (KDE Partition Manager) -[6]: /file/413591 -[7]: https://opensource.com/sites/default/files/uploads/blockdevices_newpartition.jpeg (Create a new partition) diff --git a/sources/tech/20181107 Automate a web browser with Selenium.md b/sources/tech/20181107 Automate a web browser with Selenium.md deleted file mode 100644 index 6f2f7bc155..0000000000 --- a/sources/tech/20181107 Automate a web browser with Selenium.md +++ /dev/null @@ -1,124 +0,0 @@ -translating---geekpi - -Automate a web browser with Selenium -====== - - -[Selenium][1] is a great tool for browser automation. With Selenium IDE you can record sequences of commands (like click, drag and type), validate the result and finally store this automated test for later. This is great for active development in the browser. But when you want to integrate these tests with your CI/CD flow it’s time to move on to Selenium WebDriver. - -WebDriver exposes an API with bindings for many programming languages, which lets you integrate browser tests with your other tests. This post shows you how to run WebDriver in a container and use it together with a Python program. - -### Running Selenium with Podman - -Podman is the container runtime in the following examples. See [this previous post][2] for how to get started with Podman. - -This example uses a standalone container for Selenium that contains both the WebDriver server and the browser itself. To launch the server container in the background run the following comand: - -``` -$ podman run -d --network host --privileged --name server \ - docker.io/selenium/standalone-firefox -``` - -When you run the container with the privileged flag and host networking, you can connect to this container later from a Python program. You do not need to use sudo. - -### Using Selenium from Python - -Now you can provide a simple program that uses this server. This program is minimal, but should give you an idea about what you can do: - -``` -from selenium import webdriver -from selenium.webdriver.common.desired_capabilities import DesiredCapabilities - -server ="http://127.0.0.1:4444/wd/hub" - -driver = webdriver.Remote(command_executor=server, - desired_capabilities=DesiredCapabilities.FIREFOX) - -print("Loading page...") -driver.get("https://fedoramagazine.org/") -print("Loaded") -assert "Fedora" in driver.title - -driver.quit() -print("Done.") -``` - -First the program connects to the container you already started. Then it loads the Fedora Magazine web page and asserts that “Fedora” is part of the page title. Finally, it quits the session. - -Python bindings are required in order to run the program. And since you’re already using containers, why not do this in a container as well? Save the following to a file name Dockerfile: - -``` -FROM fedora:29 -RUN dnf -y install python3 -RUN pip3 install selenium -``` - -Then build your container image using Podman, in the same folder as Dockerfile: - -``` -$ podman build -t selenium-python . -``` - -To run your program in the container, mount the file containing your Python code as a volume when you run the container: - -``` -$ podman run -t --rm --network host \ - -v $(pwd)/browser-test.py:/browser-test.py:z \ - selenium-python python3 browser-test.py -``` - -The output should look like this: - -``` -Loading page... -Loaded -Done. -``` - -### What to do next - -The example program above is minimal, and perhaps not that useful. But it barely scratched the surface of what’s possible! Check out the documentation for [Selenium][3] and for the [Python bindings][4]. There you’ll find examples for how to locate elements in a page, handle popups, or fill in forms. Drag and drop is also possible, and of course waiting for various events. - -With a few nice tests implemented, you may want to include the whole thing in your CI/CD pipeline. Luckily enough, this is fairly straightforward since everything was containerized to begin with. - -You may also be interested in setting up a [grid][5] to run the tests in parallel. Not only does this help speed things up, but it also allows you to test several different browsers at the same time. - -### Cleaning up - -When you’re done playing with your containers, you can stop and remove the standalone container with the following commands: - -``` -$ podman stop server -$ podman rm server -``` - -If you also want to free up disk space, run these commands to remove the images as well: - -``` -$ podman rmi docker.io/selenium/standalone-firefox -$ podman rmi selenium-python fedora:29 -``` - -### Conclusion - -In this post, you’ve seen how easy it is to get started with Selenium using container technology. It allowed you to automate interaction with a website, as well as test the interaction. Podman allowed you to run the containers necessary without super user privileges or the Docker daemon. Finally, the Python bindings let you use normal Python code to interact with the browser. - - --------------------------------------------------------------------------------- - -via: https://fedoramagazine.org/automate-web-browser-selenium/ - -作者：[Lennart Jern][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://fedoramagazine.org/author/lennartj/ -[b]: https://github.com/lujun9972 -[1]: https://www.seleniumhq.org/ -[2]: https://fedoramagazine.org/running-containers-with-podman/ -[3]: https://www.seleniumhq.org/docs/ -[4]: https://selenium-python.readthedocs.io -[5]: https://www.seleniumhq.org/docs/07_selenium_grid.jsp diff --git a/sources/tech/20181107 Gitbase- Exploring git repos with SQL.md b/sources/tech/20181107 Gitbase- Exploring git repos with SQL.md deleted file mode 100644 index 81abb7a4d8..0000000000 --- a/sources/tech/20181107 Gitbase- Exploring git repos with SQL.md +++ /dev/null @@ -1,93 +0,0 @@ -Gitbase: Exploring git repos with SQL -====== -Gitbase is a Go-powered open source project that allows SQL queries to be run on Git repositories. - - -Git has become the de-facto standard for code versioning, but its popularity didn't remove the complexity of performing deep analyses of the history and contents of source code repositories. - -SQL, on the other hand, is a battle-tested language to query large codebases as its adoption by projects like Spark and BigQuery shows. - -So it is just logical that at source{d} we chose these two technologies to create gitbase: the code-as-data solution for large-scale analysis of git repositories with SQL. - -[Gitbase][1] is a fully open source project that stands on the shoulders of a series of giants which made its development possible, this article aims to point out the main ones. - - - -The [gitbase][2] [playground][2] provides a visual way to use gitbase. - -### Parsing SQL with Vitess - -Gitbase's user interface is SQL. This means we need to be able to parse and understand the SQL requests that arrive through the network following the MySQL protocol. Fortunately for us, this was already implemented by our friends at YouTube and their [Vitess][3] project. Vitess is a database clustering system for horizontal scaling of MySQL. - -We simply grabbed the pieces of code that mattered to us and made it into an [open source project][4] that allows anyone to write a MySQL server in minutes (as I showed in my [justforfunc][5] episode [CSVQL—serving CSV with SQL][6]). - -### Reading git repositories with go-git - -Once we've parsed a request we still need to find how to answer it by reading the git repositories in our dataset. For this, we integrated source{d}'s most successful repository [go-git][7]. Go-git is a* *highly extensible Git implementation in pure Go. - -This allowed us to easily analyze repositories stored on disk as [siva][8] files (again an open source project by source{d}) or simply cloned with git clone. - -### Detecting languages with enry and parsing files with babelfish - -Gitbase does not stop its analytic power at the git history. By integrating language detection with our (obviously) open source project [enry][9] and program parsing with [babelfish][10]. Babelfish is a self-hosted server for universal source code parsing, turning code files into Universal Abstract Syntax Trees (UASTs) - -These two features are exposed in gitbase as the user functions LANGUAGE and UAST. Together they make requests like "find the name of the function that was most often modified during the last month" possible. - -### Making it go fast - -Gitbase analyzes really large datasets—e.g. Public Git Archive, with 3TB of source code from GitHub ([announcement][11]) and in order to do so every CPU cycle counts. - -This is why we integrated two more projects into the mix: Rubex and Pilosa. - -#### Speeding up regular expressions with Rubex and Oniguruma - -[Rubex][12] is a quasi-drop-in replacement for Go's regexp standard library package. I say quasi because they do not implement the LiteralPrefix method on the regexp.Regexp type, but I also had never heard about that method until right now. - -#### Speeding up queries with Pilosa indexes - -Rubex gets its performance from the highly optimized C library [Oniguruma][13] which it calls using [cgo][14] - -Indexes are a well-known feature of basically every relational database, but Vitess does not implement them since it doesn't really need to. - -But again open source came to the rescue with [Pilosa][15], a distributed bitmap index implemented in Go which made gitbase usable on massive datasets. Pilosa is an open source, distributed bitmap index that dramatically accelerates queries across multiple, massive datasets. - -### Conclusion - -I'd like to use this blog post to personally thank the open source community that made it possible for us to create gitbase in such a shorter period that anyone would have expected. At source{d} we are firm believers in open source and every single line of code under github.com/src-d (including our OKRs and investor board) is a testament to that. - -Would you like to give gitbase a try? The fastest and easiest way is with source{d} Engine. Download it from sourced.tech/engine and get gitbase running with a single command! - -Want to know more? Check out the recording of my talk at the [Go SF meetup][16]. - -The article was [originally published][17] on Medium and is republished here with permission. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/11/gitbase - -作者：[Francesc Campoy][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://opensource.com/users/francesc -[b]: https://github.com/lujun9972 -[1]: https://github.com/src-d/gitbase -[2]: https://github.com/src-d/gitbase-web -[3]: https://github.com/vitessio/vitess -[4]: https://github.com/src-d/go-mysql-server -[5]: http://justforfunc.com/ -[6]: https://youtu.be/bcRDXAraprk -[7]: https://github.com/src-d/go-git -[8]: https://github.com/src-d/siva -[9]: https://github.com/src-d/enry -[10]: https://github.com/bblfsh/bblfshd -[11]: https://blog.sourced.tech/post/announcing-pga/ -[12]: https://github.com/moovweb/rubex -[13]: https://github.com/kkos/oniguruma -[14]: https://golang.org/cmd/cgo/ -[15]: https://github.com/pilosa/pilosa -[16]: https://www.meetup.com/golangsf/events/251690574/ -[17]: https://medium.com/sourcedtech/gitbase-exploring-git-repos-with-sql-95ec0986386c diff --git a/sources/tech/20181107 How To Find The Execution Time Of A Command Or Process In Linux.md b/sources/tech/20181107 How To Find The Execution Time Of A Command Or Process In Linux.md deleted file mode 100644 index b24c5898a8..0000000000 --- a/sources/tech/20181107 How To Find The Execution Time Of A Command Or Process In Linux.md +++ /dev/null @@ -1,185 +0,0 @@ -How To Find The Execution Time Of A Command Or Process In Linux -====== - - -You probably know the start time of a command/process and [**how long a process is running**][1] in Unix-like systems. But, how do you when did it end and/or what is the total time taken by the command/process to complete? Well, It’s easy! On Unix-like systems, there is a utility named **‘GNU time’** that is specifically designed for this purpose. Using Time utility, we can easily measure the total execution time of a command or program in Linux operating systems. Good thing is ‘time’ command comes preinstalled in most Linux distributions, so you don’t have to bother with installation. - -### Find The Execution Time Of A Command Or Process In Linux - -To measure the execution time of a command/program, just run. - -``` -$ /usr/bin/time -p ls -``` - -Or, - -``` -$ time ls -``` - -Sample output: - -``` -dir1 dir2 file1 file2 mcelog - -real 0m0.007s -user 0m0.001s -sys 0m0.004s - -$ time ls -a -. .bash_logout dir1 file2 mcelog .sudo_as_admin_successful -.. .bashrc dir2 .gnupg .profile .wget-hsts -.bash_history .cache file1 .local .stack - -real 0m0.008s -user 0m0.001s -sys 0m0.005s -``` - -The above commands displays the total execution time of **‘ls’** command. Replace “ls” with any command/process of your choice to find the total execution time. - -Here, - - 1. **real** -refers the total time taken by command/program, - 2. **user** – refers the time taken by the program in user mode, - 3. **sys** – refers the time taken by the program in kernel mode. - - - -We can also limit the command to run only for a certain time as well. Refer the following guide for more details. - -### time vs /usr/bin/time - -As you may noticed, we used two commands **‘time’** and **‘/usr/bin/time’** in the above examples. So, you might wonder what is the difference between them. - -First, let us see what actually ‘time’ is using ‘type’ command. For those who don’t know, the **Type** command is used to find out the information about a Linux command. For more details, refer [**this guide**][2]. - -``` -$ type -a time -time is a shell keyword -time is /usr/bin/time -``` - -As you see in the above output, time is both, - - * A keyword built into the BASH shell - * An executable file i.e **/usr/bin/time** - - - -Since shell keywords take precedence over executable files, when you just run`time`command without full path, you run a built-in shell command. But, When you run `/usr/bin/time`, you run a real **GNU time** program. So, in order to access the real command, you may need to specify its explicit path. Clear, good? - -The built-in ‘time’ shell keyword is available in most shells like BASH, ZSH, CSH, KSH, TCSH etc. The ‘time’ shell keyword has less options than the executables. The only option you can use in ‘time’ keyword is **-p**. - -You know now how to find the total execution time of a given command/process using ‘time’ command. Want to know little bit more about ‘GNU time’ utility? Read on! - -### A brief introduction about ‘GNU time’ program - -The GNU time program runs a command/program with given arguments and summarizes the system resource usage as standard output after the command is completed. Unlike the ‘time’ keyword, the GNU time program not just displays the time used by the command/process, but also other resources like memory, I/O and IPC calls. - -The typical syntax of the Time command is: - -``` -/usr/bin/time [options] command [arguments...] -``` - -The ‘options’ in the above syntax refers a set of flags that can be used with time command to perform a particular functionality. The list of available options are given below. - - * **-f, –format** – Use this option to specify the format of output as you wish. - * **-p, –portability** – Use the portable output format. - * **-o file, –output=FILE** – Writes the output to **FILE** instead of displaying as standard output. - * **-a, –append** – Append the output to the FILE instead of overwriting it. - * **-v, –verbose** – This option displays the detailed description of the output of the ‘time’ utility. - * **–quiet** – This option prevents the time ‘time’ utility to report the status of the program. - - - -When using ‘GNU time’ program without any options, you will see output something like below. - -``` -$ /usr/bin/time wc /etc/hosts -9 28 273 /etc/hosts -0.00user 0.00system 0:00.00elapsed 66%CPU (0avgtext+0avgdata 2024maxresident)k -0inputs+0outputs (0major+73minor)pagefaults 0swaps -``` - -If you run the same command with the shell built-in keyword ‘time’, the output would be bit different: - -``` -$ time wc /etc/hosts -9 28 273 /etc/hosts - -real 0m0.006s -user 0m0.001s -sys 0m0.004s -``` - -Some times, you might want to write the system resource usage output to a file rather than displaying in the Terminal. To do so, use **-o** flag like below. - -``` -$ /usr/bin/time -o file.txt ls -dir1 dir2 file1 file2 file.txt mcelog -``` - -As you can see in the output, Time utility doesn’t display the output. Because, we write the output to a file named file.txt. Let us have a look at this file: - -``` -$ cat file.txt -0.00user 0.00system 0:00.00elapsed 66%CPU (0avgtext+0avgdata 2512maxresident)k -0inputs+0outputs (0major+106minor)pagefaults 0swaps -``` - -When you use **-o** flag, if there is no file named ‘file.txt’, it will create and write the output in it. If the file.txt is already present, it will overwrite its content. - -You can also append output to the file instead of overwriting it using **-a** flag. - -``` -$ /usr/bin/time -a file.txt ls -``` - -The **-f** flag allows the users to control the format of the output as per his/her liking. Say for example, the following command displays output of ‘ls’ command and shows just the user, system, and total time. - -``` -$ /usr/bin/time -f "\t%E real,\t%U user,\t%S sys" ls -dir1 dir2 file1 file2 mcelog -0:00.00 real, 0.00 user, 0.00 sys -``` - -Please be mindful that the built-in shell command ‘time’ doesn’t support all features of GNU time program. - -For more details about GNU time utility, refer the man pages. - -``` -$ man time -``` - -To know more about Bash built-in ‘Time’ keyword, run: - -``` -$ help time -``` - -And, that’s all for now. Hope this useful. - -More good stuffs to come. Stay tuned! - -Cheers! - - - --------------------------------------------------------------------------------- - -via: https://www.ostechnix.com/how-to-find-the-execution-time-of-a-command-or-process-in-linux/ - -作者：[SK][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://www.ostechnix.com/author/sk/ -[b]: https://github.com/lujun9972 -[1]: https://www.ostechnix.com/find-long-process-running-linux/ -[2]: https://www.ostechnix.com/the-type-command-tutorial-with-examples-for-beginners/ diff --git a/sources/tech/20181107 Top 30 OpenStack Interview Questions and Answers.md b/sources/tech/20181107 Top 30 OpenStack Interview Questions and Answers.md deleted file mode 100644 index e00fc5452b..0000000000 --- a/sources/tech/20181107 Top 30 OpenStack Interview Questions and Answers.md +++ /dev/null @@ -1,324 +0,0 @@ -Top 30 OpenStack Interview Questions and Answers -====== -Now a days most of the firms are trying to migrate their IT infrastructure and Telco Infra into private cloud i.e OpenStack. If you planning to give interviews on Openstack admin profile, then below list of interview questions might help you to crack the interview. - - - -### Q:1 Define OpenStack and its key components? - -Ans: It is a bundle of opensource software, which all in combine forms a provide cloud software known as OpenStack.OpenStack is known as Stack of Open source Software or Projects. - -Following are the key components of OpenStack - - * **Nova** – It handles the Virtual machines at compute level and performs other computing task at compute or hypervisor level. - * **Neutron** – It provides the networking functionality to VMs, Compute and Controller Nodes. - * **Keystone** – It provides the identity service for all cloud users and openstack services. In other words, we can say Keystone a method to provide access to cloud users and services. - * **Horizon** – It provides a GUI (Graphical User Interface), using the GUI Admin can all day to day operations task at ease. - * **Cinder** – It provides the block storage functionality, generally in OpenStack Cinder is integrated with Chef and ScaleIO to service block storage to Compute & Controller nodes. - * **Swift** – It provides the object storage functionality. Generally, Glance images are on object storage. External storage like ScaleIO can work as Object storage too and can easily be integrated with Glance Service. - * **Glance** – It provides Cloud image services, using glance admin used to upload and download cloud images. - * **Heat** – It provides an orchestration service or functionality. Using Heat admin can easily VMs as stack and based on requirements VMs in the stack can be scale-in and Scale-out - * **Ceilometer** – It provides the telemetry and billing services. - - - -### Q:2 What are services generally run on a controller node? - -Ans: Following services run on a controller node: - - * Identity Service ( KeyStone) - * Image Service ( Glance) - * Nova Services like Nova API, Nova Scheduler & Nova DB - * Block & Object Service - * Ceilometer Service - * MariaDB / MySQL and RabbitMQ Service - * Management services of Networking (Neutron) and Networking agents - * Orchestration Service (Heat) - - - -### Q:3 What are the services generally run on a Compute Node? - -Ans: Following services run on a compute node, - - * Nova-Compute - * Networking Services like OVS - - - -### Q:4 What is the default location of VMs on the Compute Nodes? - -Ans: VMs in the Compute node are stored at “ **/var/lib/nova/instances** ” - -### Q:5 What is default location of glance images? - -Ans: As the Glance service runs on a controller node, all the glance images are store under the folder “ **/var/lib/glance/images** ” on a controller node. - -Read More : [**How to Create and Delete Virtual Machine(VM) from Command line in OpenStack**][1] - -### Q:6 Tell me the command how to spin a VM from Command Line? - -Ans: We can easily spin a new VM using the following openstack command, - -``` -# openstack server create --flavor {flavor-name} --image {Image-Name-Or-Image-ID} --nic net-id={Network-ID} --security-group {Security_Group_ID} –key-name {Keypair-Name} -``` - -### Q:7 How to list the network namespace of a tenant in OpenStack? - -Ans: Network namespace of a tenant can be listed using “ip net ns” command - -``` -~# ip netns list -qdhcp-a51635b1-d023-419a-93b5-39de47755d2d -haproxy -vrouter -``` - -### Q:8 How to execute command inside network namespace in openstack? - -Ans: Let’s assume we want to execute “ifconfig” command inside the network namespace “qdhcp-a51635b1-d023-419a-93b5-39de47755d2d”, then run the beneath command, - -Syntax : ip netns exec {network-space} - -``` -~# ip netns exec qdhcp-a51635b1-d023-419a-93b5-39de47755d2d "ifconfig" -``` - -### Q:9 How to upload and download a cloud image in Glance from command line? - -Ans: A Cloud image can be uploaded in glance from command using beneath openstack command, - -``` -~# openstack image create --disk-format qcow2 --container-format bare --public --file {Name-Cloud-Image}.qcow2 -``` - -Use below openstack command to download a cloud image from command line, - -``` -~# glance image-download --file --progress -``` - -### Q:10 How to reset error state of a VM into active in OpenStack env? - -Ans: There are some scenarios where some VMs went to error state and this error state can be changed into active state using below commands, - -``` -~# nova reset-state --active {Instance_id} -``` - -### Q:11 How to get list of available Floating IPs from command line? - -Ans: Available floating ips can be listed using the below command, - -``` -~]# openstack ip floating list | grep None | head -10 -``` - -### Q:12 How to provision a virtual machine in specific availability zone and compute Host? - -Ans: Let’s assume we want to provision a VM on the availability zone NonProduction in compute-02, use the beneath command to accomplish this, - -``` -~]# openstack server create --flavor m1.tiny --image cirros --nic net-id=e0be93b8-728b-4d4d-a272-7d672b2560a6 --security-group NonProd_SG --key-name linuxtec --availability-zone NonProduction:compute-02 nonprod_testvm -``` - -### Q:13 How to get list of VMs which are provisioned on a specific Compute node? - -Ans: Let’s assume we want to list the vms which are provisioned on compute-0-19, use below - -Syntax: openstack server list –all-projects –long -c Name -c Host | grep -i {Compute-Node-Name} - -``` -~# openstack server list --all-projects --long -c Name -c Host | grep -i compute-0-19 -``` - -### Q:14 How to view the console log of an openstack instance from command line? - -Ans: Console logs of an instance can be viewed from the command line using the following commands, - -First get the ID of an instance and then use the below command, - -``` -~# openstack console log show {Instance-id} -``` - -### Q:15 How to get console URL of an openstack instance? - -Ans: Console URL of an instance can be retrieved from command line using the below openstack command, - -``` -~# openstack console url show {Instance-id} -``` - -### Q:16 How to create a bootable cinder / block storage volume from command line? - -Ans: To Create a bootable cinder or block storage volume (assume 8 GB) , refer the below steps: - - * Get Image list using below - - - -``` -~# openstack image list | grep -i cirros -| 89254d46-a54b-4bc8-8e4d-658287c7ee92 | cirros | active | -``` - - * Create bootable volume of size 8 GB using cirros image - - - -``` -~# cinder create --image-id 89254d46-a54b-4bc8-8e4d-658287c7ee92 --display-name cirros-bootable-vol 8 -``` - -### Q:17 How to list all projects or tenants that has been created in your opentstack? - -Ans: Projects or tenants list can be retrieved from the command using the below openstack command, - -``` -~# openstack project list --long -``` - -### Q:18 How to list the endpoints of openstack services? - -Ans: Openstack service endpoints are classified into three categories, - - * Public Endpoint - * Internal Endpoint - * Admin Endpoint - - - -Use below openstack command to view endpoints of each openstack service, - -``` -~# openstack catalog list -``` - -To list the endpoint of a specific service like keystone use below, - -``` -~# openstack catalog show keystone -``` - -Read More : [**Step by Step Instance Creation Flow in OpenStack**][2] - -### Q:19 In which order we should restart nova services on a controller node? - -Ans: Following order should be followed to restart the nova services on openstack controller node, - - * service nova-api restart - * service nova-cert restart - * service nova-conductor restart - * service nova-consoleauth restart - * service nova-scheduler restart - - - -### Q:20 Let’s assume DPDK ports are configured on compute node for data traffic, now how you will check the status of dpdk ports? - -Ans: As DPDK ports are configured via openvSwitch (OVS), use below commands to check the status, - -### Q:21 How to add new rules to the existing SG(Security Group) from command line in openstack? - -Ans: New rules to the existing SG in openstack can be added using the neutron command, - -``` -~# neutron security-group-rule-create --protocol --port-range-min --port-range-max --direction --remote-ip-prefix Security-Group-Name -``` - -### Q:22 How to view the OVS bridges configured on Controller and Compute Nodes? - -Ans: OVS bridges on Controller and Compute nodes can be viewed using below command, - -``` -~]# ovs-vsctl show -``` - -### Q:23 What is the role of Integration Bridge(br-int) on the Compute Node ? - -Ans: The integration bridge (br-int) performs VLAN tagging and untagging for the traffic coming from and to the instance running on the compute node. - -Packets leaving the n/w interface of an instance goes through the linux bridge (qbr) using the virtual interface qvo. The interface qvb is connected to the Linux Bridge & interface qvo is connected to integration bridge (br-int). The qvo port on integration bridge has an internal VLAN tag that gets appended to packet header when a packet reaches to the integration bridge. - -### Q:24 What is the role of Tunnel Bridge (br-tun) on the compute node? - -Ans: The tunnel bridge (br-tun) translates the VLAN tagged traffic from integration bridge to the tunnel ids using OpenFlow rules. - -br-tun (tunnel bridge) allows the communication between the instances on different networks. Tunneling helps to encapsulate the traffic travelling over insecure networks, br-tun supports two overlay networks i.e GRE and VXLAN - -### Q:25 What is the role of external OVS bridge (br-ex)? - -Ans: As the name suggests, this bridge forwards the traffic coming to and from the network to allow external access to instances. br-ex connects to the physical interface like eth2, so that floating IP traffic for tenants networks is received from the physical network and routed to the tenant network ports. - -### Q:26 What is function of OpenFlow rules in OpenStack Networking? - -Ans: OpenFlow rules is a mechanism that define how a packet will reach to destination starting from its source. OpenFlow rules resides in flow tables. The flow tables are part of OpenFlow switch. - -When a packet arrives to a switch, it is processed by the first flow table, if it doesn’t match any flow entries in the table then packet is dropped or forwarded to another table. - -### Q:27 How to display the information about a OpenFlow switch (like ports, no. of tables, no of buffer)? - -Ans: Let’s assume we want to display the information about OpenFlow switch (br-int), run the following command, - -``` -root@compute-0-15# ovs-ofctl show br-int -OFPT_FEATURES_REPLY (xid=0x2): dpid:0000fe981785c443 -n_tables:254, n_buffers:256 -capabilities: FLOW_STATS TABLE_STATS PORT_STATS QUEUE_STATS ARP_MATCH_IP -actions: output enqueue set_vlan_vid set_vlan_pcp strip_vlan mod_dl_src mod_dl_dst mod_nw_src mod_nw_dst mod_nw_tos mod_tp_src mod_tp_dst - 1(patch-tun): addr:3a:c6:4f:bd:3e:3b - config: 0 - state: 0 - speed: 0 Mbps now, 0 Mbps max - 2(qvob35d2d65-f3): addr:b2:83:c4:0b:42:3a - config: 0 - state: 0 - current: 10GB-FD COPPER - speed: 10000 Mbps now, 0 Mbps max - ……………………………………… -``` - -### Q:28 How to display the entries for all the flows in a switch? - -Ans: Flows entries of a switch can be displayed using the command ‘ **ovs-ofctl dump-flows** ‘ - -Let’s assume we want to display flow entries of OVS integration bridge (br-int), - -### Q:29 What are Neutron Agents and how to list all neutron agents? - -Ans: OpenStack neutron server acts as the centralized controller, the actual network configurations are executed either on compute and network nodes. Neutron agents are software entities that carry out configuration changes on compute or network nodes. Neutron agents communicate with the main neutron service via Neuron API and message queue. - -Neutron agents can be listed using the following command, - -``` -~# openstack network agent list -c ‘Agent type’ -c Host -c Alive -c State -``` - -### Q:30 What is CPU pinning? - -Ans: CPU pinning refers to reserving the physical cores for specific virtual machine. It is also known as CPU isolation or processor affinity. The configuration is in two parts: - - * it ensures that virtual machine can only run on dedicated cores - * it also ensures that common host processes don’t run on those cores - - - -In other words we can say pinning is one to one mapping of a physical core to a guest vCPU. - --------------------------------------------------------------------------------- - -via: https://www.linuxtechi.com/openstack-interview-questions-answers/ - -作者：[Pradeep Kumar][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: http://www.linuxtechi.com/author/pradeep/ -[b]: https://github.com/lujun9972 -[1]: https://www.linuxtechi.com/create-delete-virtual-machine-command-line-openstack/ -[2]: https://www.linuxtechi.com/step-by-step-instance-creation-flow-in-openstack/ diff --git a/sources/tech/20181108 Choosing a printer for Linux.md b/sources/tech/20181108 Choosing a printer for Linux.md deleted file mode 100644 index a3b87329db..0000000000 --- a/sources/tech/20181108 Choosing a printer for Linux.md +++ /dev/null @@ -1,74 +0,0 @@ -Choosing a printer for Linux -====== -Linux offers widespread support for printers. Learn how to take advantage of it. - - -We've made significant strides toward the long-rumored paperless society, but we still need to print hard copies of documents from time to time. If you're a Linux user and have a printer without a Linux installation disk or you're in the market for a new device, you're in luck. That's because most Linux distributions (as well as MacOS) use the Common Unix Printing System ([CUPS][1]), which contains drivers for most printers available today. This means Linux offers much wider support than Windows for printers. - -### Selecting a printer - -If you're buying a new printer, the best way to find out if it supports Linux is to check the documentation on the box or the manufacturer's website. You can also search the [Open Printing][2] database. It's a great resource for checking various printers' compatibility with Linux. - -Here are some Open Printing results for Linux-compatible Canon printers. - - -The screenshot below is Open Printing's results for a Hewlett-Packard LaserJet 4050—according to the database, it should work "perfectly." The recommended driver is listed along with generic instructions letting me know it works with CUPS, Line Printing Daemon (LPD), LPRng, and more. - - -In all cases, it's best to check the manufacturer's website and ask other Linux users before buying a printer. - -### Checking your connection - -There are several ways to connect a printer to a computer. If your printer is connected through USB, it's easy to check the connection by issuing **lsusb** at the Bash prompt. - -``` -$ lsusb -``` - -The command returns **Bus 002 Device 004: ID 03f0:ad2a Hewlett-Packard** —it's not much information, but I can tell the printer is connected. I can get more information about the printer by entering the following command: - -``` -$ dmesg | grep -i usb -``` - -The results are much more verbose. - - -If you're trying to connect your printer to a parallel port (assuming your computer has a parallel port—they're rare these days), you can check the connection with this command: - -``` -$ dmesg | grep -i parport -``` - -The information returned can help me select the right driver for my printer. I have found that if I stick to popular, name-brand printers, most of the time I get good results. - -### Setting up your printer software - -Both Fedora Linux and Ubuntu Linux contain easy printer setup tools. [Fedora][3] maintains an excellent wiki for answers to printing issues. The tools are easily launched from Settings in the GUI or by invoking **system-config-printer** on the command line. - - - -Hewlett-Packard's [HP Linux Imaging and Printing][4] (HPLIP) software, which supports Linux printing, is probably already installed on your Linux system; if not, you can [download][5] the latest version for your distribution. Printer manufacturers [Epson][6] and [Brother][7] also have web pages with Linux printer drivers and information. - -What's your favorite Linux printer? Please share your opinion in the comments. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/11/choosing-printer-linux - -作者：[Don Watkins][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://opensource.com/users/don-watkins -[b]: https://github.com/lujun9972 -[1]: https://www.cups.org/ -[2]: http://www.openprinting.org/printers -[3]: https://fedoraproject.org/wiki/Printing -[4]: https://developers.hp.com/hp-linux-imaging-and-printing -[5]: https://developers.hp.com/hp-linux-imaging-and-printing/gethplip -[6]: https://epson.com/Support/wa00821 -[7]: https://support.brother.com/g/s/id/linux/en/index.html?c=us_ot&lang=en&comple=on&redirect=on diff --git a/sources/tech/20181108 My Google-free Android life.md b/sources/tech/20181108 My Google-free Android life.md new file mode 100644 index 0000000000..4e94af0de8 --- /dev/null +++ b/sources/tech/20181108 My Google-free Android life.md @@ -0,0 +1,191 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (My Google-free Android life) +[#]: via: (https://lushka.al/my-android-setup/) +[#]: author: (Anxhelo Lushka https://lushka.al/) + +My Google-free Android life +====== + +People have been asking me a lot lately about my phone, my Android setup and how I manage to use my smartphone without Google Services. Well, this is a post that aims to address precisely that. I would like to make this article really beginner-friendly so I’ll try to go slow, going through things one by one and including screenshots so you can have a better view on how things happen and work like. + +At first I’ll start with why Google Services are (imo) bad for your device. I could cut it short and guide you to this [post][1] by [Richard Stallman][2], but I’m grabbing a few main points from it and adding them here. + + * Nonfree software required + * In general, most Google services require running nonfree Javascript code. Nowadays, nothing whatsoever appears if Javascript is disabled, even making a Google account requires running nonfree software (Javascript sent by the site), same thing for logging in. + * Surveillance + * Google quietly combines its ad-tracking profiles with its browsing profiles and stores a huge amount of data on each user. + * Terms of Service + * Google cuts off accounts for users that resell Pixel phones. They lose access to all of their mail and documents stored in Google servers under that account. + * Censorship + * Amazon and Google have cut off domain-fronting, a feature used to enable people in tyrannical countries to reach communication systems that are banned there. + * Google has agreed to perform special censorship of Youtube for the government of Pakistan, deleting views that the state opposes. This will help the illiberal Pakistani state suppress dissent. + * Youtube’s “content ID” automatically deletes posted videos in a way copyright law does not require. + + + +These are just a few reasons, but you can read the post by RMS I linked above in which he tries to explain these points in detail. Although it may look like a tinfoil hat reaction to you, all these actions already happen everyday in real life. + +### Next on the list, my setup and a tutorial on how I achieved it + +I own a **[Xiaomi Redmi Note 5 Pro][3]** smartphone (codename **whyred** ), produced in China by [Xiaomi][4], which I bought for around 185 EUR 4 months ago (from the time of writing this post). + +Now you might be thinking, ‘but why did you buy a Chinese brand, they are not reliable’. Yes, it is not made from the usuals as you would expect, such as Samsung (which people often associate with Android, which is plain wrong), OnePlus, Nokia etc, but you should know almost every phone is produced in China. + +There were a few reasons I chose this phone, first one of course being the price. It is a quite **budget-friendly** device, so most people are able to afford it. Next one would be the specs, which on paper (not only) are pretty decents for the price tag. With a 6 inch screen (Full HD resolution), a **4000 mAh battery** (superb battery life), 4GB of RAM, 64GB of storage, dual back cameras (12MP + 5MP), a front camera with flash (13MP) and a decent efficient Snapdragon 636, it was probably the best choice at that moment. + +The issue with it was that it came with [MIUI][5], the Android skin that Xiaomi ships with most of its devices (except the Android One project devices). Yes, it is not that horrible, it has some extra features, but the problems lie deeper within. One of the reasons these devices from Xiaomi are so cheap (afaik they only have 5-10% win margin from sales) is that **they include data mining and ads in the system altogether with MIUI**. In this way, the system apps requires extra unnecessary permissions that mine your data and bombard you with ads, from which Xiaomi earns money. + +Funnily enough, the Weather app included wanted access to my contacts and to make calls, why would it need that if it would just show the weather? Another case was with the Recorder app, it also required contacts and internet permissions, probably to send those recordings back to Xiaomi. + +To fix this, I’d have to format the phone and get rid of MIUI. This has become increasingly difficult with the latest phones in the market. + +The concept of formatting a phone is simple, you remove the existing system and install a new one of your preference (Android-only in this case). To do that, you have to have your [bootloader][6] unlocked. + +> A bootloader is a computer program that loads an operating system (OS) or runtime environment for the computer after completion of the self-tests. — [Wikipedia][7] + +The problem here is that Xiaomi has a specific policy about the bootloader unlocking. A few months ago, the process was like this. You would have to [make a request][8] to Xiaomi to obtain an unlock code for your phone, by giving a valid reason, but this would not always work, as they could just refuse your request without reason and explanation. + +Now, that process has changed. You’ll have to download a specific software from Xiaomi, called [Mi Unlock][9], install it in your Windows PC, [activate Debugging Settings in Developer Options][10] on your phone, reboot to the bootloader mode (by holding the Volume Down + Power button while the phone is off) and connect the phone to your computer to start a process called “Approval”. This process starts a timer on the Xiaomi servers that will allow you to **unlock the phone only after a period of 15 days** (or a month in some rare cases, totally random) goes by. + +![Mi Unlock app][11] + +After this period of 15 days has passed, you have to re-connect your phone and do the same procedure as above, then by pressing the Unlock button your bootloader will be unlocked and this will allow you to install other ROM-s (systems). **Careful, make sure to backup your data because unlocking the bootloader deletes everything in the phone**. + +The next step would be finding a system ([ROM][12]) that works for your device. I searched through the [XDA Developers Forum][13], which is a place where Android developers and users exchange ideas, apps etc. Fortunately, my phone is quite popular so it had [its own forum category][14]. There, I skimmed through some popular ROM-s for my device and decided to use the [AOSiP ROM][15] (AOSiP standing for Android Open Source illusion Project). + +**EDIT** : Someone emailed me to say that my article is exactly what [/e/][16] does and is targeted to. I wanted to say thank you for reaching out but that is not true at all. The reasoning behind my opinion about /e/ can also be found in this [website][17], but I’ll list a few of the reasons here. + +eelo is a “foundation” that got over 200K € in funding from Kickstarter and IndieGoGo, promising to create a mobile OS and web services that are open and secure and protect your privacy. + + 1. Their OS is based on LineageOS 14.1 (Android 7.1) with microG and other open source apps with it, which already exists for a long time now and it’s called [Lineage for microG][18]. + 2. Instead of building all apps from the source code, they download the APKs from [APKPure][19] and put them in the ROM, without knowing if those APKs contain proprietary code/malware in them. + 3. At one point, they were literally just removing the Lineage copyright header from their code and adding theirs. + 4. They love to delete negative feedback and censor their users’ opinions in their Telegram group chat. + + + +In conclusion, I **don’t recommend using /e/** ROM-s (at least until now). + +Another thing you would likely want to do is have [root access][20] to your phone, to make it truly yours and modify files in the system, such as use a system-wide adblocker etc. To do this, I decided to use [Magisk][21], a godsend app developed by a student to help you gain root access on your device and install what are called [modules][22], basically software. + +After downloading the ROM and Magisk, I had to install them on my phone. To do that, I moved the files to my SD card on the phone. Now, to install the system, I had to use something called a [recovery system][23]. The one I use is called [TWRP][24] (standing for TeamWin Recovery Project), a popular solution. + +To install the recovery system (sounds hard, I know), I had to [flash][20] the file on the phone. To do that, I connected my phone with the computer (Fedora Linux system) and with something called [ADB Tools][25] I issued a command that overwrites the system recovery with the custom one I had. + +> fastboot flash recovery twrp.img + +After this was done, I turned off the phone and kept Volume Up + Power button pressed until I saw the TWRP screen show up. That meant I was good to go and it was ready to receive my commands. + +![TWRP screen][26] + +Next step was to **issue a Wipe command** , necessary when you first install a custom ROM on your phone. As you can see from the image above, the Wipe command clears the Data, Cache and Dalvik (there is also an advanced option that allows us to tick a box to delete the System one too, as we don’t need the old one anymore). + +This takes a few moments and after that, your phone is basically clean. Now it’s time to **install the system**. By pressing the Install button on the main screen, we select the zip file we added there before (the ROM file) and swipe the screen to install it. Next, we have to install Magisk, which gives us root access to the device. + +**EDIT** : As some more experienced/power Android users might have noticed until now, there is no [GApps][27] (Google Apps) included. This is what we call GApps-less in the Android world, not having those packages installed at all. + +Note that one of the downsides of not having Google Services installed is that some of your apps might not work, for example their notifications might take longer to arrive or might not even work at all (this is what happens with Mattermost app for me). This happens because these apps use [Google Cloud Messaging][28] (now called [Firebase][29]) to wake the phone and push notifications to your phone. + +You can solve this (partially) by installing and using [microG][30] which provides some features of Google Services but allows for more control on your side. I don’t recommend using this because it still helps Google Services and you don’t really give up on them, but it’s a good start if you want to quit Google slowly and not go cold turkey on it. + +After successfully installing both, now we reboot the phone and **tada** 🎉, we are in the main screen. + +### Next part, installing the apps and configuring everything + +This is where things start to get easier. To install the apps, I use [F-Droid][31], an alternative app store that includes **only free and open source apps**. If you need apps that are not available there, you can use [Aurora Store][32], a client to download apps from the Play Store without using your Google account or getting tracked. + +F-Droid has what are called repos, a “storehouse” that contains apps you can install. I use the default ones and have added another one from [IzzyOnDroid][33], that contains some more apps not available from the default F-Droid repo and is updated more often. + +![My repos][34] + +Below you will find a list of the apps I have installed, what they replace and their use. + +This is pretty much **my list of the most useful F-Droid apps** I use, but unfortunately these are NOT the only apps I use. The proprietary apps I use (I know, I might sound a hypocrite, but not everything is replaceable, not yet at least) are as below: + + * AliExpress + * Boost for Reddit + * Google Camera (coupled with Camera API 2, this app allows me to take wonderful pictures with a 185 EUR phone, it’s just too impressive) + * Instagram + * MediaBox HD (allows me to stream movies) + * Mi Fit (an app that pairs with my Mi Band 2) + * MyVodafoneAL (the carrier app) + * ProtonMail (email app) + * Shazam Encore (to find those songs you usually listen in coffee shops) + * Snapseed (photo editing app, really simple, powerful and quite good) + * Spotify (music streaming) + * Titanium Backup (to backup my app data, wifi passwords, calls log etc.) + * ViPER4Android FX (music equalizer) + * VSCO (photo editing, never use it really) + * WhatsApp (E2E proprietary messaging app, almost everyone I know has it) + * WiFi Map (mapped hotspots that are available, handy when abroad) + + + +This is pretty much it, all the apps I use on my phone. **The configs are then pretty simple and straightforward and I can give a few tips**. + + 1. Read and check the permissions of apps carefully, don’t click ‘Install’ mindlessly. + 2. Try to use as many open source apps as possible, they both respect your privacy and are free (as in both free beer and freedom). + 3. Use a VPN as much as you can, find a reputable one and don’t use free ones, otherwise you get to be the product and you’ll get your data harvested. + 4. Don’t keep your WiFi/mobile data/location on all the time, it might be a security risk. + 5. Try not to rely on fingerprint unlock only, or better yet use only PIN/password/pattern unlock, as biometric data can be cloned and used against you, for example to unlock your phone and steal your data. + + + +And as a bonus for reading far down here, **a screenshot of my home screen** right now. + +![Screenshot][35] + + +-------------------------------------------------------------------------------- + +via: https://lushka.al/my-android-setup/ + +作者：[Anxhelo Lushka][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://lushka.al/ +[b]: https://github.com/lujun9972 +[1]: https://stallman.org/google.html +[2]: https://en.wikipedia.org/wiki/Richard_Stallman +[3]: https://www.gsmarena.com/xiaomi_redmi_note_5_pro-8893.php +[4]: https://en.wikipedia.org/wiki/Xiaomi +[5]: https://en.wikipedia.org/wiki/MIUI +[6]: https://forum.xda-developers.com/wiki/Bootloader +[7]: https://en.wikipedia.org/wiki/Booting +[8]: https://en.miui.com/unlock/ +[9]: http://www.miui.com/unlock/apply.php +[10]: https://www.youtube.com/watch?v=7zhEsJlivFA +[11]: https://lushka.al//assets/img/posts/mi-unlock.png +[12]: https://www.xda-developers.com/what-is-custom-rom-android/ +[13]: https://forum.xda-developers.com/ +[14]: https://forum.xda-developers.com/redmi-note-5-pro +[15]: https://forum.xda-developers.com/redmi-note-5-pro/development/rom-aosip-8-1-t3804473 +[16]: https://e.foundation +[17]: https://ewwlo.xyz/evil +[18]: https://lineage.microg.org/ +[19]: https://apkpure.com/ +[20]: https://lifehacker.com/5789397/the-always-up-to-date-guide-to-rooting-any-android-phone +[21]: https://forum.xda-developers.com/apps/magisk/official-magisk-v7-universal-systemless-t3473445 +[22]: https://forum.xda-developers.com/apps/magisk +[23]: http://www.smartmobilephonesolutions.com/content/android-system-recovery +[24]: https://dl.twrp.me/whyred/ +[25]: https://developer.android.com/studio/command-line/adb +[26]: https://lushka.al//assets/img/posts/android-twrp.png +[27]: https://opengapps.org/ +[28]: https://developers.google.com/cloud-messaging/ +[29]: https://firebase.google.com/docs/cloud-messaging/ +[30]: https://microg.org/ +[31]: https://f-droid.org/ +[32]: https://f-droid.org/en/packages/com.dragons.aurora/ +[33]: https://android.izzysoft.de/repo +[34]: https://lushka.al//assets/img/posts/android-fdroid-repos.jpg +[35]: https://lushka.al//assets/img/posts/android-screenshot.jpg +[36]: https://creativecommons.org/licenses/by-nc-sa/4.0/ diff --git a/sources/tech/20181108 The Difference Between more, less And most Commands.md b/sources/tech/20181108 The Difference Between more, less And most Commands.md deleted file mode 100644 index e2c2c5fcf6..0000000000 --- a/sources/tech/20181108 The Difference Between more, less And most Commands.md +++ /dev/null @@ -1,234 +0,0 @@ -HankChow translating - -The Difference Between more, less And most Commands -====== - -If you’re a newbie Linux user, you might be confused with these three command like utilities, namely **more** , **less** and **most**. No problem! In this brief guide, I will explain the differences between these three commands, with some examples in Linux. To be precise, they are more or less same with slight differences. All these commands comes preinstalled in most Linux distributions. - -First, we will discuss about ‘more’ command. - -### The ‘more’ program - -The **‘more’** is an old and basic terminal pager or paging program that is used to open a given file for interactive reading. If the content of the file is too large to fit in one screen, it displays the contents page by page. You can scroll through the contents of the file by pressing **ENTER** or **SPACE BAR** keys. But one limitation is you can scroll in **forward direction only** , not backwards. That means, you can scroll down, but can’t go up. - - - -**Update:** - -A fellow Linux user has pointed out that more command do allow backward scrolling. The original version allowed only the forward scrolling. However, the newer implementations allows limited backward movement. To scroll backwards, just press **b**. The only limitation is that it doesn’t work for pipes (ls|more for example). - -To quit, press **q**. - -**more command examples:** - -Open a file, for example ostechnix.txt, for interactive reading: - -``` -$ more ostechnix.txt -``` - -To search for a string, type search query after the forward slash (/) like below: - -``` -/linux -``` - -To go to then next matching string, press **‘n’**. - -To open the file start at line number 10, simply type: - -``` -$ more +10 file -``` - -The above command show the contents of ostechnix.txt starting from 10th line. - -If you want the ‘more’ utility to prompt you to continue reading file by pressing the space bar key, just use **-d** flag: - -``` -$ more -d ostechnix.txt -``` - -![][2] - -As you see in the above screenshot, the more command prompts you to press SPACE to continue. - -To view the summary of all options and keybindings in the help section, press **h**. - -For more details about **‘more’** command, refer man pages. - -``` -$ man more -``` - -### The ‘less’ program - -The **‘less** ‘ command is also used to open a given file for interactive reading, allowing scrolling and search. If the content of the file is too large, it pages the output and so you can scroll page by page. Unlike the ‘more’ command, it allows scrolling on both directions. That means, you can scroll up and down through a file. - - - -So, feature-wise, ‘less’ has more advantages than ‘more’ command. Here are some notable advantages of ‘less’ command: - - * Allows forward and backward scrolling, - * Search in forward and backward directions, - * Go to the end and start of the file immediately, - * Open the given file in an editor. - - - -**less command examples:** - -Open a file: - -``` -$ less ostechnix.txt -``` - -Press **SPACE BAR** or **ENTER** key to go down and press **‘b’** to go up. - -To perform a forward search, type search query after the forward slash ( **/** ) like below: - -``` -/linux -``` - -To go to then next matching string, press **‘n’**. To go back to the previous matching string, press **N** (shift+n). - -To perform a backward search, type search query after the question mark ( **?** ) like below: - -``` -?linux -``` - -Press **n/N** to go to **next/previous** match. - -To open the currently opened file in an editor, press **v**. It will open your file in your default text editor. You can now edit, remove, rename the text in the file. - -To view the summary of less commands, options, keybindings, press **h**. - -To quit, press **q**. - -For more details about ‘less’ command, refer the man pages. - -``` -$ man less -``` - -### The ‘most’ program - -The ‘most’ terminal pager has more features than ‘more’ and ‘less’ programs. Unlike the previous utilities, the ‘most’ command can able to open more than one file at a time. You can easily switch between the opened files, edit the current file, jump to the **N** th line in the opened file, split the current window in half, lock and scroll windows together and so on. By default, it won’t wrap the long lines, but truncates them and provides a left/right scrolling option. - -**most command examples:** - -Open a single file: - -``` -$ most ostechnix1.txt -``` - -To edit the current file, press **e**. - -To perform a forward search, press **/** or **S** or **f** and type the search query. Press **n** to find the next matching string in the current direction. - -![][3] - -To perform a backward search, press **?** and type the search query. Similarly, press **n** to find the next matching string in the current direction. - -Open multiple files at once: - -``` -$ most ostechnix1.txt ostechnix2.txt ostechnix3.txt -``` - -If you have opened multiple files, you can switch to next file by typing **:n**. Use **UP/DOWN** arrow keys to select next file and hit **ENTER** key to view the chosen file. - - -To open a file at the first occurrence of given string, for example **linux** : - -``` -$ most file +/linux -``` - -To view the help section, press **h** at any time. - -**List of all keybindings:** - -Navigation: - - * **SPACE, D** – Scroll down one screen. - * **DELETE, U** – Scroll Up one screen. - * **DOWN arrow** – Move Down one line. - * **UP arrow** – Move Up one line. - * **T** – Goto Top of File. - * **B** – Goto Bottom of file. - * **> , TAB** – Scroll Window right. - * **<** – Scroll Window left. - * **RIGHT arrow** – Scroll Window left by 1 column. - * **LEFT arrow** – Scroll Window right by 1 column. - * **J, G** – Goto nth line. For example, to jump to the 10th line, simply type **“100j”** (without quotes). - * **%** – Goto percent. - - - -Window Commands: - - * **Ctrl-X 2, Ctrl-W 2** – Split window. - * **Ctrl-X 1, Ctrl-W 1** – Make only one window. - * **O, Ctrl-X O** – Move to other window. - * **Ctrl-X 0 (zero)** – Delete Window. - - - -Search through files: - - * **S, f, /** – Search forward. - * **?** – Search Backward. - * **N** – Find next match in current search direction. - - - -Exit: - - * **q** – Quit MOST program. All opened files will be closed. - * **:N, :n** – Quit this file and view next (Use UP/DOWN arrow keys to select next file). - - - -For more details about ‘most’ command, refer the man pages. - -``` -$ man most -``` - -### TL;DR - -**more** – An old, very basic paging program. Allows only forward navigation and limited backward navigation. - -**less** – It has more features than ‘more’ utility. Allows both forward and backward navigation and search functionalities. It starts faster than text editors like **vi** when you open large text files. - -**most** – It has all features of above programs including additional features, like opening multiple files at a time, locking and scrolling all windows together, splitting the windows and more. - -And, that’s all for now. Hope you got the basic idea about these three paging programs. I’ve covered only the basics. You can learn more advanced options and functionalities of these programs by looking into the respective program’s man pages. - -More good stuffs to come. Stay tuned! - -Cheers! - - - --------------------------------------------------------------------------------- - -via: https://www.ostechnix.com/the-difference-between-more-less-and-most-commands/ - -作者：[SK][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://www.ostechnix.com/author/sk/ -[b]: https://github.com/lujun9972 -[1]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 -[2]: http://www.ostechnix.com/wp-content/uploads/2018/11/more-1.png -[3]: http://www.ostechnix.com/wp-content/uploads/2018/11/most-1-1.gif diff --git a/sources/tech/20181112 A Free, Secure And Cross-platform Password Manager.md b/sources/tech/20181112 A Free, Secure And Cross-platform Password Manager.md deleted file mode 100644 index 66d34769c4..0000000000 --- a/sources/tech/20181112 A Free, Secure And Cross-platform Password Manager.md +++ /dev/null @@ -1,137 +0,0 @@ -A Free, Secure And Cross-platform Password Manager -====== - - - -In this modern Internet era, you will surely have multiple accounts on lot of websites. It could be a personal or official mail account, social or professional network account, GitHub account, and ecommerce account etc. So you should have several different passwords for different accounts. I am sure that you are already aware that setting up same password to multiple accounts is crazy and dangerous practice. If an attacker managed to breach one of your accounts, it’s highly likely he/she will try to access other accounts you have with the same password. So, it is **highly recommended to set different passwords** to different accounts. - -However, remembering several passwords might be difficult. You can write them in a paper. But it is not an efficient method either and you might lose them over a period of time. This is where the password managers comes in help. The password managers are like a repository where you can store all your passwords for different accounts and lock them down with a master password. By this way, all you need to remember is just the master password. We already have reviewed an open source password manager named [**KeeWeb**][1]. Today, we are going to see yet another password manager called **Buttercup**. - -### About Buttercup - -Buttercup is a free, open source, secure and cross-platform password manager written using **NodeJS**. It helps you to store all your login credentials of different accounts in an encrypted archive, which can be stored in your local system or any remote services like DropBox, ownCloud, NextCloud and WebDAV-based services. It uses strong **256bit AES encryption** method to save your sensitive data with a master password. So, no one can access your login details except those who have the master password. Buttercup currently supports Linux, Mac OS and Windows. It is also available a browser extension and mobile app. so, you can access the same archive you use on the desktop application and browser extension in your Android or iOS devices as well. - -### Installing Buttercup Password Manager - -Buttercup is currently available as **.deb** , **.rpm** packages, portable AppImage and tar archives for Linux platform. Head over to the [**releases pages**][2] and download and install the version you want to use. - -Buttercup desktop application is also available in [**AUR**][3], so you can install on Arch-based systems using AUR helper programs, such as [**Yay**][4], as shown below: - -``` -$ yay -S buttercup-desktop -``` - -If you have downloaded the portable AppImage file, make it executable using command: - -``` -$ chmod +x buttercup-desktop-1.11.0-x86_64.AppImage -``` - -Then, launch it using command: - -``` -$ ./buttercup-desktop-1.11.0-x86_64.AppImage -``` - -Once you run this command, it will prompt whether you like to integrate Buttercup AppImage with your system. If you choose ‘Yes’, this will add it to your applications menu and install icons. If you don’t do this, you can still launch the application by double-clicking on the AppImage or using the above command from the Terminal. - -### Add archives - -When you launch it for the first time, you will see the following welcome screen: - - -We haven’t added any archives yet, so let us add one. To do so, click on the “New Archive File” button and type the name of the archive file and choose the location to save it. - - -You can name it as you wish. I named it mine as “mypass”. The archives will have extension **.bcup** at the end and saved in the location of your choice. - -If you already have created one, simply choose it by clicking on “Open Archive File”. - -Next, buttercup will prompt you to enter a master password to the newly created archive. It is recommended to provide a strong password to protect the archives from the unauthorized access. - - - -We have now created an archive and secured it with a master password. Similarly, you can create any number of archives and protect them with a password. - -Let us go ahead and add the account details in the archives. - -### Adding entries (login credentials) in the archives - -Once you created or opened the archive, you will see the following screen. - - - -It is like a vault where we are going to save our login credentials of different online accounts. As you can see, we haven’t added any entries yet. Let us add some. - -To add a new entry, click “ADD ENTRY” button on the lower right corner and enter your account information you want to save. - - - -If you want to add any extra detail, there is an “ADD NEW FIELD” option right under the each entry. Just click on it and add as many as fields you want to include in the entries. - -Once you added all entries, you will see them on the right pane of the Buttercup interface. - -![][6] - -### Creating new groups - -You can also group login details under different name for easy recognition. Say for example, you can group all your mail accounts under a distinct name named “my_mails”. By default, your login details will be saved under “General” group. To create a new group, click “NEW GROUP” button and provide the name for the group. When creating new entries inside a new group, just click on the group name and start adding the entries as shown above. - -### Manage and access login details - -The data stored in the archives can be edited, moved to different groups, or entirely deleted at anytime. For instance, if you want to copy the username or password to clipboard, right click on the entry and choose “Copy to Clipboard” option. - -![][7] - -To edit/modify the data in the future, just click “Edit” button under the selected entry. - -### Save archives on remote location - -By default, Buttercup will save your data on the local system. However, you can save them on different remote services, such as Dropbox, ownCloud/NextCloud, WebDAV-based service. - -To connect to these services, go to **File - > Connect Cloud Sources**. - - - -And, choose the service you want to connect and authorize it to save your data. - -![][8] - -You can also connect those services from the Buttercup welcome screen while adding the archives. - -### Import/Export - -Buttercup allows you to import or export data to or from other password managers, such as 1Password, Lastpass and KeePass. You can also export your data and access them from another system or device, for example on your Android phone. You can export Buttercup vaults to CSV format as well. - -![][9] - -Buttercup is a simple, yet mature and fully functional password manager. It is being actively developed for years. If you ever in need of a password manager, Buttercup might a good choice. For more details, refer the project website and github page. - -And, that’s all for now. Hope this was useful. More good stuffs to come. Stay tuned! - -Cheers! - - - --------------------------------------------------------------------------------- - -via: https://www.ostechnix.com/buttercup-a-free-secure-and-cross-platform-password-manager/ - -作者：[SK][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://www.ostechnix.com/author/sk/ -[b]: https://github.com/lujun9972 -[1]: https://www.ostechnix.com/keeweb-an-open-source-cross-platform-password-manager/ -[2]: https://github.com/buttercup/buttercup-desktop/releases/latest -[3]: https://aur.archlinux.org/packages/buttercup-desktop/ -[4]: https://www.ostechnix.com/yay-found-yet-another-reliable-aur-helper/ -[5]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 -[6]: http://www.ostechnix.com/wp-content/uploads/2018/11/buttercup-6.png -[7]: http://www.ostechnix.com/wp-content/uploads/2018/11/buttercup-7.png -[8]: http://www.ostechnix.com/wp-content/uploads/2018/11/buttercup-9.png -[9]: http://www.ostechnix.com/wp-content/uploads/2018/11/buttercup-10.png diff --git a/sources/tech/20181112 The Source History of Cat.md b/sources/tech/20181112 The Source History of Cat.md deleted file mode 100644 index 1cb1139033..0000000000 --- a/sources/tech/20181112 The Source History of Cat.md +++ /dev/null @@ -1,94 +0,0 @@ -The Source History of Cat -====== -I once had a debate with members of my extended family about whether a computer science degree is a degree worth pursuing. I was in college at the time and trying to decide whether I should major in computer science. My aunt and a cousin of mine believed that I shouldn’t. They conceded that knowing how to program is of course a useful and lucrative thing, but they argued that the field of computer science advances so quickly that everything I learned would almost immediately be outdated. Better to pick up programming on the side and instead major in a field like economics or physics where the basic principles would be applicable throughout my lifetime. - -I knew that my aunt and cousin were wrong and decided to major in computer science. (Sorry, aunt and cousin!) It is easy to see why the average person might believe that a field like computer science, or a profession like software engineering, completely reinvents itself every few years. We had personal computers, then the web, then phones, then machine learning… technology is always changing, so surely all the underlying principles and techniques change too. Of course, the amazing thing is how little actually changes. Most people, I’m sure, would be stunned to know just how old some of the important software on their computer really is. I’m not talking about flashy application software, admittedly—my copy of Firefox, the program I probably use the most on my computer, is not even two weeks old. But, if you pull up the manual page for something like `grep`, you will see that it has not been updated since 2010 (at least on MacOS). And the original version of `grep` was written in 1974, which in the computing world was back when dinosaurs roamed Silicon Valley. People (and programs) still depend on `grep` every day. - -My aunt and cousin thought of computer technology as a series of increasingly elaborate sand castles supplanting one another after each high tide clears the beach. The reality, at least in many areas, is that we steadily accumulate programs that have solved problems. We might have to occasionally modify these programs to avoid software rot, but otherwise they can be left alone. `grep` is a simple program that solves a still-relevant problem, so it survives. Most application programming is done at a very high level, atop a pyramid of much older code solving much older problems. The ideas and concepts of 30 or 40 years ago, far from being obsolete today, have in many cases been embodied in software that you can still find installed on your laptop. - -I thought it would be interesting to take a look at one such old program and see how much it had changed since it was first written. `cat` is maybe the simplest of all the Unix utilities, so I’m going to use it as my example. Ken Thompson wrote the original implementation of `cat` in 1969. If I were to tell somebody that I have a program on my computer from 1969, would that be accurate? How much has `cat` really evolved over the decades? How old is the software on our computers? - -Thanks to repositories like [this one][1], we can see exactly how `cat` has evolved since 1969. I’m going to focus on implementations of `cat` that are ancestors of the implementation I have on my Macbook. You will see, as we trace `cat` from the first versions of Unix down to the `cat` in MacOS today, that the program has been rewritten more times than you might expect—but it ultimately works more or less the same way it did fifty years ago. - -### Research Unix - -Ken Thompson and Dennis Ritchie began writing Unix on a PDP 7. This was in 1969, before C, so all of the early Unix software was written in PDP 7 assembly. The exact flavor of assembly they used was unique to Unix, since Ken Thompson wrote his own assembler that added some features on top of the assembler provided by DEC, the PDP 7’s manufacturer. Thompson’s changes are all documented in [the original Unix Programmer’s Manual][2] under the entry for `as`, the assembler. - -[The first implementation][3] of `cat` is thus in PDP 7 assembly. I’ve added comments that try to explain what each instruction is doing, but the program is still difficult to follow unless you understand some of the extensions Thompson made while writing his assembler. There are two important ones. First, the `;` character can be used to separate multiple statements on the same line. It appears that this was used most often to put system call arguments on the same line as the `sys` instruction. Second, Thompson added support for “temporary labels” using the digits 0 through 9. These are labels that can be reused throughout a program, thus being, according to the Unix Programmer’s Manual, “less taxing both on the imagination of the programmer and on the symbol space of the assembler.” From any given instruction, you can refer to the next or most recent temporary label `n` using `nf` and `nb` respectively. For example, if you have some code in a block labeled `1:`, you can jump back to that block from further down by using the instruction `jmp 1b`. (But you cannot jump forward to that block from above without using `jmp 1f` instead.) - -The most interesting thing about this first version of `cat` is that it contains two names we should recognize. There is a block of instructions labeled `getc` and a block of instructions labeled `putc`, demonstrating that these names are older than the C standard library. The first version of `cat` actually contained implementations of both functions. The implementations buffered input so that reads and writes were not done a character at a time. - -The first version of `cat` did not last long. Ken Thompson and Dennis Ritchie were able to persuade Bell Labs to buy them a PDP 11 so that they could continue to expand and improve Unix. The PDP 11 had a different instruction set, so `cat` had to be rewritten. I’ve marked up [this second version][4] of `cat` with comments as well. It uses new assembler mnemonics for the new instruction set and takes advantage of the PDP 11’s various [addressing modes][5]. (If you are confused by the parentheses and dollar signs in the source code, those are used to indicate different addressing modes.) But it also leverages the `;` character and temporary labels just like the first version of `cat`, meaning that these features must have been retained when `as` was adapted for the PDP 11. - -The second version of `cat` is significantly simpler than the first. It is also more “Unix-y” in that it doesn’t just expect a list of filename arguments—it will, when given no arguments, read from `stdin`, which is what `cat` still does today. You can also give this version of `cat` an argument of `-` to indicate that it should read from `stdin`. - -In 1973, in preparation for the release of the Fourth Edition of Unix, much of Unix was rewritten in C. But `cat` does not seem to have been rewritten in C until a while after that. [The first C implementation][6] of `cat` only shows up in the Seventh Edition of Unix. This implementation is really fun to look through because it is so simple. Of all the implementations to follow, this one most resembles the idealized `cat` used as a pedagogic demonstration in K&R C. The heart of the program is the classic two-liner: - -``` -while ((c = getc(fi)) != EOF) - putchar(c); -``` - -There is of course quite a bit more code than that, but the extra code is mostly there to ensure that you aren’t reading and writing to the same file. The other interesting thing to note is that this implementation of `cat` only recognized one flag, `-u`. The `-u` flag could be used to avoid buffering input and output, which `cat` would otherwise do in blocks of 512 bytes. - -### BSD - -After the Seventh Edition, Unix spawned all sorts of derivatives and offshoots. MacOS is built on top of Darwin, which in turn is derived from the Berkeley Software Distribution (BSD), so BSD is the Unix offshoot we are most interested in. BSD was originally just a collection of useful programs and add-ons for Unix, but it eventually became a complete operating system. BSD seems to have relied on the original `cat` implementation up until the fourth BSD release, known as 4BSD, when support was added for a whole slew of new flags. [The 4BSD implementation][7] of `cat` is clearly derived from the original implementation, though it adds a new function to implement the behavior triggered by the new flags. The naming conventions already used in the file were adhered to—the `fflg` variable, used to mark whether input was being read from `stdin` or a file, was joined by `nflg`, `bflg`, `vflg`, `sflg`, `eflg`, and `tflg`, all there to record whether or not each new flag was supplied in the invocation of the program. These were the last command-line flags added to `cat`; the man page for `cat` today lists these flags and no others, at least on Mac OS. 4BSD was released in 1980, so this set of flags is 38 years old. - -`cat` would be entirely rewritten a final time for BSD Net/2, which was, among other things, an attempt to avoid licensing issues by replacing all AT&T Unix-derived code with new code. BSD Net/2 was released in 1991. This final rewrite of `cat` was done by Kevin Fall, who graduated from Berkeley in 1988 and spent the next year working as a staff member at the Computer Systems Research Group (CSRG). Fall told me that a list of Unix utilities still implemented using AT&T code was put up on a wall at CSRG and staff were told to pick the utilities they wanted to reimplement. Fall picked `cat` and `mknod`. The `cat` implementation bundled with MacOS today is built from a source file that still bears his name at the very top. His version of `cat`, even though it is a relatively trivial program, is today used by millions. - -[Fall’s original implementation][8] of `cat` is much longer than anything we have seen so far. Other than support for a `-?` help flag, it adds nothing in the way of new functionality. Conceptually, it is very similar to the 4BSD implementation. It is only longer because Fall separates the implementation into a “raw” mode and a “cooked” mode. The “raw” mode is `cat` classic; it prints a file character for character. The “cooked” mode is `cat` with all the 4BSD command-line options. The distinction makes sense but it also pads out the implementation so that it seems more complex at first glance than it actually is. There is also a fancy error handling function at the end of the file that further adds to its length. - -### MacOS - -In 2001, Apple launched Mac OS X. The launch was an important one for Apple, because Apple had spent many years trying and failing to replace its existing operating system (classic Mac OS), which had long been showing its age. There were two previous attempts to create a new operating system internally, but both went nowhere; in the end, Apple bought NeXT, Steve Jobs’ company, which had developed an operating system and object-oriented programming framework called NeXTSTEP. Apple took NeXTSTEP and used it as a basis for Mac OS X. NeXTSTEP was in part built on BSD, so using NeXTSTEP as a starting point for Mac OS X brought BSD-derived code right into the center of the Apple universe. - -The very first release of Mac OS X thus includes [an implementation][9] of `cat` pulled from the NetBSD project. NetBSD, which remains in development today, began as a fork of 386BSD, which in turn was based directly on BSD Net/2. So the first Mac OS X implementation of `cat` is Kevin Fall’s `cat`. The only thing that had changed over the intervening decade was that Fall’s error-handling function `err()` was removed and the `err()` function made available by `err.h` was used in its place. `err.h` is a BSD extension to the C standard library. - -The NetBSD implementation of `cat` was later swapped out for FreeBSD’s implementation of `cat`. [According to Wikipedia][10], Apple began using FreeBSD instead of NetBSD in Mac OS X 10.3 (Panther). But the Mac OS X implementation of `cat`, according to Apple’s own open source releases, was not replaced until Mac OS X 10.5 (Leopard) was released in 2007. The [FreeBSD implementation][11] that Apple swapped in for the Leopard release is the same implementation on Apple computers today. As of 2018, the implementation has not been updated or changed at all since 2007. - -So the Mac OS `cat` is old. As it happens, it is actually two years older than its 2007 appearance in MacOS X would suggest. [This 2005 change][12], which is visible in FreeBSD’s Github mirror, was the last change made to FreeBSD’s `cat` before Apple pulled it into Mac OS X. So the Mac OS X `cat` implementation, which has not been kept in sync with FreeBSD’s `cat` implementation, is officially 13 years old. There’s a larger debate to be had about how much software can change before it really counts as the same software; in this case, the source file has not changed at all since 2005. - -The `cat` implementation used by Mac OS today is not that different from the implementation that Fall wrote for the 1991 BSD Net/2 release. The biggest difference is that a whole new function was added to provide Unix domain socket support. At some point, a FreeBSD developer also seems to have decided that Fall’s `raw_args()` function and `cook_args()` should be combined into a single function called `scanfiles()`. Otherwise, the heart of the program is still Fall’s code. - -I asked Fall how he felt about having written the `cat` implementation now used by millions of Apple users, either directly or indirectly through some program that relies on `cat` being present. Fall, who is now a consultant and a co-author of the most recent editions of TCP/IP Illustrated, says that he is surprised when people get such a thrill out of learning about his work on `cat`. Fall has had a long career in computing and has worked on many high-profile projects, but it seems that many people still get most excited about the six months of work he put into rewriting `cat` in 1989. - -### The Hundred-Year-Old Program - -In the grand scheme of things, computers are not an old invention. We’re used to hundred-year-old photographs or even hundred-year-old camera footage. But computer programs are in a different category—they’re high-tech and new. At least, they are now. As the computing industry matures, will we someday find ourselves using programs that approach the hundred-year-old mark? - -Computer hardware will presumably change enough that we won’t be able to take an executable compiled today and run it on hardware a century from now. Perhaps advances in programming language design will also mean that nobody will understand C in the future and `cat` will have long since been rewritten in another language. (Though C has already been around for fifty years, and it doesn’t look like it is about to be replaced any time soon.) But barring all that, why not just keep using the `cat` we have forever? - -I think the history of `cat` shows that some ideas in computer science are very durable indeed. Indeed, with `cat`, both the idea and the program itself are old. It may not be accurate to say that the `cat` on my computer is from 1969. But I could make a case for saying that the `cat` on my computer is from 1989, when Fall wrote his implementation of `cat`. Lots of other software is just as ancient. So maybe we shouldn’t think of computer science and software development primarily as fields that disrupt the status quo and invent new things. Our computer systems are built out of historical artifacts. At some point, we may all spend more time trying to understand and maintain those historical artifacts than we spend writing new code. - -If you enjoyed this post, more like it come out every two weeks! Follow [@TwoBitHistory][13] on Twitter or subscribe to the [RSS feed][14] to make sure you know when a new post is out. - - --------------------------------------------------------------------------------- - -via: https://twobithistory.org/2018/11/12/cat.html - -作者：[Two-Bit History][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://twobithistory.org -[b]: https://github.com/lujun9972 -[1]: https://github.com/dspinellis/unix-history-repo -[2]: https://www.bell-labs.com/usr/dmr/www/man11.pdf -[3]: https://gist.github.com/sinclairtarget/47143ba52b9d9e360d8db3762ee0cbf5#file-1-cat-pdp7-s -[4]: https://gist.github.com/sinclairtarget/47143ba52b9d9e360d8db3762ee0cbf5#file-2-cat-pdp11-s -[5]: https://en.wikipedia.org/wiki/PDP-11_architecture#Addressing_modes -[6]: https://gist.github.com/sinclairtarget/47143ba52b9d9e360d8db3762ee0cbf5#file-3-cat-v7-c -[7]: https://gist.github.com/sinclairtarget/47143ba52b9d9e360d8db3762ee0cbf5#file-4-cat-bsd4-c -[8]: https://gist.github.com/sinclairtarget/47143ba52b9d9e360d8db3762ee0cbf5#file-5-cat-net2-c -[9]: https://gist.github.com/sinclairtarget/47143ba52b9d9e360d8db3762ee0cbf5#file-6-cat-macosx-c -[10]: https://en.wikipedia.org/wiki/Darwin_(operating_system) -[11]: https://gist.github.com/sinclairtarget/47143ba52b9d9e360d8db3762ee0cbf5#file-7-cat-macos-10-13-c -[12]: https://github.com/freebsd/freebsd/commit/a76898b84970888a6fd015e15721f65815ea119a#diff-6e405d5ab5b47ca2a131ac7955e5a16b -[13]: https://twitter.com/TwoBitHistory -[14]: https://twobithistory.org/feed.xml -[15]: https://twitter.com/TwoBitHistory/status/1051826516844322821?ref_src=twsrc%5Etfw diff --git a/sources/tech/20181113 4 tips for learning Golang.md b/sources/tech/20181113 4 tips for learning Golang.md deleted file mode 100644 index 50921b57a3..0000000000 --- a/sources/tech/20181113 4 tips for learning Golang.md +++ /dev/null @@ -1,75 +0,0 @@ -4 tips for learning Golang -====== -Arriving in Golang land: A senior developer's journey. - - -In the summer of 2014... - -> IBM: "We need you to go figure out this Docker thing." -> Me: "OK." -> IBM: "Start contributing and just get involved." -> Me: "OK." (internal voice): "This is written in Go. What's that?" (Googles) "Oh, a programming language. I've learned a few of those in my career. Can't be that hard." - -My university's freshman programming class was taught using VAX assembler. In data structures class, we used Pascal—loaded via diskette on tired, old PCs in the library's computer center. In one upper-level course, I had a professor that loved to show all examples in ADA. I learned a bit of C via playing with various Unix utilities' source code on our Sun workstations. At IBM we used C—and some x86 assembler—for the OS/2 source code, and we heavily used C++'s object-oriented features for a joint project with Apple. I learned shell scripting soon after, starting with csh, but moving to Bash after finding Linux in the mid-'90s. I was thrust into learning m4 (arguably more of a macro-processor than a programming language) while working on the just-in-time (JIT) compiler in IBM's custom JVM code when porting it to Linux in the late '90s. - -Fast-forward 20 years... I'd never been nervous about learning a new programming language. But [Go][1] felt different. I was going to contribute publicly, upstream on GitHub, visible to anyone interested enough to look! I didn't want to be the laughingstock, the Go newbie as a 40-something-year-old senior developer! We all know that programmer pride that doesn't like to get bruised, no matter your experience level. - -My early investigations revealed that Go seemed more committed to its "idiomatic-ness" than some languages. It wasn't just about getting the code to compile; I needed to be able to write code "the Go way." - -Now that I'm four years and several hundred pull requests into my personal Go journey, I don't claim to be an expert, but I do feel a lot more comfortable contributing and writing Go code than I did in 2014. So, how do you teach an old guy new tricks—or at least a new programming language? Here are four steps that were valuable in my own journey to Golang land. - -### 1. Don't skip the fundamentals - -While you might be able to get by with copying code and hunting and pecking your way through early learnings (who has time to read the manual?!?), Go has a very readable [language spec][2] that was clearly written to be read and understood, even if you don't have a master's in language or compiler theory. Given that Go made some unique decisions about the order of the **parameter:type** constructs and has interesting language features like channels and goroutines, it is important to get grounded in these new concepts. Reading this document alongside [Effective Go][3], another great resource from the Golang creators, will give you a huge boost in readiness to use the language effectively and properly. - -### 2. Learn from the best - -There are many valuable resources for digging in and taking your Go knowledge to the next level. All the talks from any recent [GopherCon][4] can be found online, like this exhaustive list from [GopherCon US in 2018][5]. Talks range in expertise and skill level, but you can easily find something you didn't know about Go by watching the talks. [Francesc Campoy][6] created a Go programming video series called [JustForFunc][7] that has an ever-increasing number of episodes to expand your Go knowledge and understanding. A quick search on "Golang" reveals many other video and online resources for those who want to learn more. - -Want to look at code? Many of the most popular cloud-native projects on GitHub are written in Go: [Docker/Moby][8], [Kubernetes][9], [Istio][10], [containerd][11], [CoreDNS][12], and many others. Language purists might rate some projects better than others regarding idiomatic-ness, but these are all good starting points to see how large codebases are using Go in highly active projects. - -### 3. Use good language tools - -You will learn quickly about the value of [gofmt][13]. One of the beautiful aspects of Go is that there is no arguing about code formatting guidelines per project— **gofmt** is built into the language runtime, and it formats Go code according to a set of stable, well-understood language rules. I don't know of any Golang-based project that doesn't insist on checking with **gofmt** for pull requests as part of continuous integration. - -Beyond the wide, valuable array of useful tools built directly into the runtime/SDK, I strongly recommend using an editor or IDE with good Golang support features. Since I find myself much more often at a command line, I rely on Vim plus the great [vim-go][14] plugin. I also like what Microsoft has offered with [VS Code][15], especially with its [Go language][16] plugins. - -Looking for a debugger? The [Delve][17] project has been improving and maturing and is a strong contender for doing [gdb][18]-like debugging on Go binaries. - -### 4. Jump in and write some Go! - -You'll never get better at writing Go unless you start trying. Find a project that has some "help needed" issues flagged and make a contribution. If you are already using an open source project written in Go, find out if there are some bugs that have beginner-level solutions and make your first pull request. As with most things in life, the only real way to improve is through practice, so get going. - -And, as it turns out, apparently you can teach an old senior developer new tricks—or languages at least. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/11/learning-golang - -作者：[Phill Estes][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://opensource.com/users/estesp -[b]: https://github.com/lujun9972 -[1]: https://golang.org/ -[2]: https://golang.org/ref/spec -[3]: https://golang.org/doc/effective_go.html -[4]: https://www.gophercon.com/ -[5]: https://tqdev.com/2018-gophercon-2018-videos-online -[6]: https://twitter.com/francesc -[7]: https://www.youtube.com/channel/UC_BzFbxG2za3bp5NRRRXJSw -[8]: https://github.com/moby/moby -[9]: https://github.com/kubernetes/kubernetes -[10]: https://github.com/istio/istio -[11]: https://github.com/containerd/containerd -[12]: https://github.com/coredns/coredns -[13]: https://blog.golang.org/go-fmt-your-code -[14]: https://github.com/fatih/vim-go -[15]: https://code.visualstudio.com/ -[16]: https://code.visualstudio.com/docs/languages/go -[17]: https://github.com/derekparker/delve -[18]: https://www.gnu.org/software/gdb/ diff --git a/sources/tech/20181113 An introduction to Udev- The Linux subsystem for managing device events.md b/sources/tech/20181113 An introduction to Udev- The Linux subsystem for managing device events.md deleted file mode 100644 index c406c491b0..0000000000 --- a/sources/tech/20181113 An introduction to Udev- The Linux subsystem for managing device events.md +++ /dev/null @@ -1,228 +0,0 @@ -An introduction to Udev: The Linux subsystem for managing device events -====== -Create a script that triggers your computer to do a specific action when a specific device is plugged in. - - -Udev is the Linux subsystem that supplies your computer with device events. In plain English, that means it's the code that detects when you have things plugged into your computer, like a network card, external hard drives (including USB thumb drives), mouses, keyboards, joysticks and gamepads, DVD-ROM drives, and so on. That makes it a potentially useful utility, and it's well-enough exposed that a standard user can manually script it to do things like performing certain tasks when a certain hard drive is plugged in. - -This article teaches you how to create a [udev][1] script triggered by some udev event, such as plugging in a specific thumb drive. Once you understand the process for working with udev, you can use it to do all manner of things, like loading a specific driver when a gamepad is attached, or performing an automatic backup when you attach your backup drive. - -### A basic script - -The best way to work with udev is in small chunks. Don't write the entire script upfront, but instead start with something that simply confirms that udev triggers some custom event. - -Depending on your goal for your script, you can't guarantee you will ever see the results of a script with your own eyes, so make sure your script logs that it was successfully triggered. The usual place for log files is in the **/var** directory, but that's mostly the root user's domain. For testing, use **/tmp** , which is accessible by normal users and usually gets cleaned out with a reboot. - -Open your favorite text editor and enter this simple script: - -``` -#!/usr/bin/bash - -echo $date > /tmp/udev.log -``` - -Place this in **/usr/local/bin** or some such place in the default executable path. Call it **trigger.sh** and, of course, make it executable with **chmod +x**. - -``` -$ sudo mv trigger.sh /usr/local/bin -$ sudo chmod +x /usr/local/bin/trigger.sh -``` - -This script has nothing to do with udev. When it executes, the script places a timestamp in the file **/tmp/udev.log**. Test the script yourself: - -``` -$ /usr/local/bin/trigger.sh -$ cat /tmp/udev.log -Tue Oct 31 01:05:28 NZDT 2035 -``` - -The next step is to make udev trigger the script. - -### Unique device identification - -In order for your script to be triggered by a device event, udev must know under what conditions it should call the script. In real life, you can identify a thumb drive by its color, the manufacturer, and the fact that you just plugged it into your computer. Your computer, however, needs a different set of criteria. - -Udev identifies devices by serial numbers, manufacturers, and even vendor ID and product ID numbers. Since this is early in your udev script's lifespan, be as broad, non-specific, and all-inclusive as possible. In other words, you want first to catch nearly any valid udev event to trigger your script. - -With the **udevadm monitor** command, you can tap into udev in real time and see what it sees when you plug in different devices. Become root and try it. - -``` -$ su -# udevadm monitor -``` - -The monitor function prints received events for: - - * UDEV: the event udev sends out after rule processing - * KERNEL: the kernel uevent - - - -With **udevadm monitor** running, plug in a thumb drive and watch as all kinds of information is spewed out onto your screen. Notice that the type of event is an **ADD** event. That's a good way to identify what type of event you want. - -The **udevadm monitor** command provides a lot of good info, but you can see it with prettier formatting with the command **udevadm info** , assuming you know where your thumb drive is currently located in your **/dev** tree. If not, unplug and plug your thumb drive back in, then immediately issue this command: - -``` -$ su -c 'dmesg | tail | fgrep -i sd*' -``` - -If that command returned **sdb: sdb1** , for instance, you know the kernel has assigned your thumb drive the **sdb** label. - -Alternately, you can use the **lsblk** command to see all drives attached to your system, including their sizes and partitions. - -Now that you have established where your drive is located in your filesystem, you can view udev information about that device with this command: - -``` -# udevadm info -a -n /dev/sdb | less -``` - -This returns a lot of information. Focus on the first block of info for now. - -Your job is to pick out parts of udev's report about a device that are most unique to that device, then tell udev to trigger your script when those unique attributes are detected. - -The **udevadm info** process reports on a device (specified by the device path), then "walks" up the chain of parent devices. For every device found, it prints all possible attributes using a key-value format. You can compose a rule to match according to the attributes of a device plus attributes from one single parent device. - -``` -looking at device '/devices/000:000/blah/blah//block/sdb': - KERNEL=="sdb" - SUBSYSTEM=="block" - DRIVER=="" - ATTR{ro}=="0" - ATTR{size}=="125722368" - ATTR{stat}==" 2765 1537 5393" - ATTR{range}=="16" - ATTR{discard\_alignment}=="0" - ATTR{removable}=="1" - ATTR{blah}=="blah" -``` - -A udev rule must contain one attribute from one single parent device. - -Parent attributes are things that describe a device from the most basic level, such as it's something that has been plugged into a physical port or it is something with a size or this is a removable device. - -Since the KERNEL label of **sdb** can change depending upon how many other drives were plugged in before you plugged that thumb drive in, that's not the optimal parent attribute for a udev rule. However, it works for a proof of concept, so you could use it. An even better candidate is the SUBSYSTEM attribute, which identifies that this is a "block" system device (which is why the **lsblk** command lists the device). - -Open a file called **80-local.rules** in **/etc/udev/rules.d** and enter this code: - -``` -SUBSYSTEM=="block", ACTION=="add", RUN+="/usr/local/bin/trigger.sh" -``` - -Save the file, unplug your test thumb drive, and reboot. - -Wait, reboot on a Linux machine? - -Theoretically, you can just issue **udevadm control --reload** , which should load all rules, but at this stage in the game, it's best to eliminate all variables. Udev is complex enough, and you don't want to be lying in bed all night wondering if that rule didn't work because of a syntax error or if you just should have rebooted. So reboot regardless of what your POSIX pride tells you. - -When your system is back online, switch to a text console (with Ctl+Alt+F3 or similar) and plug in your thumb drive. If you are running a recent kernel, you will probably see a bunch of output in your console when you plug in the drive. If you see an error message such as Could not execute /usr/local/bin/trigger.sh, you probably forgot to make the script executable. Otherwise, hopefully all you see is a device was plugged in, it got some kind of kernel device assignment, and so on. - -Now, the moment of truth: - -``` -$ cat /tmp/udev.log -Tue Oct 31 01:35:28 NZDT 2035 -``` - -If you see a very recent date and time returned from **/tmp/udev.log** , udev has successfully triggered your script. - -### Refining the rule into something useful - -The problem with this rule is that it's very generic. Plugging in a mouse, a thumb drive, or someone else's thumb drive will indiscriminately trigger your script. Now is the time to start focusing on the exact thumb drive you want to trigger your script. - -One way to do this is with the vendor ID and product ID. To get these numbers, you can use the **lsusb** command. - -``` -$ lsusb -Bus 001 Device 002: ID 8087:0024 Slacker Corp. Hub -Bus 002 Device 002: ID 8087:0024 Slacker Corp. Hub -Bus 003 Device 005: ID 03f0:3307 TyCoon Corp. -Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 hub -Bus 001 Device 003: ID 13d3:5165 SBo Networks -``` - -In this example, the **03f0:3307** before **TyCoon Corp.** denotes the idVendor and idProduct attributes. You can also see these numbers in the output of **udevadm info -a -n /dev/sdb | grep vendor** , but I find the output of **lsusb** a little easier on the eyes. - -You can now include these attributes in your rule. - -``` -SUBSYSTEM=="block", ATTRS{idVendor}=="03f0", ACTION=="add", RUN+="/usr/local/bin/thumb.sh" -``` - -Test this (yes, you should still reboot, just to make sure you're getting fresh reactions from udev), and it should work the same as before, only now if you plug in, say, a thumb drive manufactured by a different company (therefore with a different idVendor) or a mouse or a printer, the script won't be triggered. - -Keep adding new attributes to further focus in on that one unique thumb drive you want to trigger your script. Using **udevadm info -a -n /dev/sdb** , you can find out things like the vendor name, sometimes a serial number, or the product name, and so on. - -For your own sanity, be sure to add only one new attribute at a time. Most mistakes I have made (and have seen other people online make) is to throw a bunch of attributes into their udev rule and wonder why the thing no longer works. Testing attributes one by one is the safest way to ensure udev can identify your device successfully. - -### Security - -This brings up the security concerns of writing udev rules to automatically do something when a drive is plugged in. On my machines, I don't even have auto-mount turned on, and yet this article proposes scripts and rules that execute commands just by having something plugged in. - -Two things to bear in mind here. - - 1. Focus your udev rules once you have them working so they trigger scripts only when you really want them to. Executing a script that blindly copies data to or from your computer is a bad idea in case anyone who happens to be carrying the same brand of thumb drive plugs it into your box. - 2. Do not write your udev rule and scripts and forget about them. I know which computers have my udev rules on them, and those boxes are most often my personal computers, not the ones I take around to conferences or have in my office at work. The more "social" a computer is, the less likely it is to get a udev rule on it that could potentially result in my data ending up on someone else's device or someone else's data or malware on my device. - - - -In other words, as with so much of the power provided by a GNU system, it is your job to be mindful of how you are wielding that power. If you abuse it or fail to treat it with respect, it very well could go horribly wrong. - -### Udev in the real world - -Now that you can confirm that your script is triggered by udev, you can turn your attention to the function of the script. Right now, it is useless, doing nothing more than logging the fact that it has been executed. - -I use udev to trigger [automated backups][2] of my thumb drives. The idea is that the master copies of my active documents are on my thumb drive (since it goes everywhere I go and could be worked on at any moment), and those master documents get backed up to my computer each time I plug the drive into that machine. In other words, my computer is the backup drive and my production data is mobile. The source code is available, so feel free to look at the code of attachup for further examples of constraining your udev tests. - -Since that's what I use udev for the most, it's the example I'll use here, but udev can grab lots of other things, like gamepads (this is useful on systems that aren't set to load the xboxdrv module when a gamepad is attached) and cameras and microphones (useful to set inputs when a specific mic is attached), so realize that it's good for a lot more than this one example. - -A simple version of my backup system is a two-command process: - -``` -SUBSYSTEM=="block", ATTRS{idVendor}=="03f0", ACTION=="add", SYMLINK+="safety%n" -SUBSYSTEM=="block", ATTRS{idVendor}=="03f0", ACTION=="add", RUN+="/usr/local/bin/trigger.sh" -``` - -The first line detects my thumb drive with the attributes already discussed, then assigns the thumb drive a symlink within the device tree. The symlink it assigns is **safety%n**. The **%n** is a udev macro that resolves to whatever number the kernel gives to the device, such as sdb1, sdb2, sdb3, and so on. So **%n** would be the 1 or the 2 or the 3. - -This creates a symlink in the dev tree, so it does not interfere with the normal process of plugging in a device. This means that if you use a desktop environment that likes to auto-mount devices, you won't be causing problems for it. - -The second line runs the script. - -My backup script looks like this: - -``` -#!/usr/bin/bash - -mount /dev/safety1 /mnt/hd -sleep 2 -rsync -az /mnt/hd/ /home/seth/backups/ && umount /dev/safety1 -``` - -The script uses the symlink, which avoids the possibility of udev naming the drive something unexpected (for instance, if I have a thumb drive called DISK plugged into my computer already, and I plug in my other thumb drive also called DISK, the second one will be labeled DISK_, which would foil my script). It mounts **safety1** (the first partition of the drive) at my preferred mount point of **/mnt/hd**. - -Once safely mounted, it uses [rsync][3] to back up the drive to my backup folder (my actual script uses rdiff-backup, and yours can use whatever automated backup solution you prefer). - -### Udev is your dev - -Udev is a very flexible system and enables you to define rules and functions in ways that few other systems dare provide users. Learn it and use it, and enjoy the power of POSIX. - -This article builds on content from the [Slackermedia Handbook][4], which is licensed under the [GNU Free Documentation License 1.3][5]. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/11/udev - -作者：[Seth Kenlon][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://opensource.com/users/seth -[b]: https://github.com/lujun9972 -[1]: https://linux.die.net/man/8/udev -[2]: https://gitlab.com/slackermedia/attachup -[3]: https://opensource.com/article/17/1/rsync-backup-linux -[4]: http://slackermedia.info/handbook/doku.php?id=backup -[5]: http://www.gnu.org/licenses/fdl-1.3.html diff --git a/sources/tech/20181113 The alias And unalias Commands Explained With Examples.md b/sources/tech/20181113 The alias And unalias Commands Explained With Examples.md deleted file mode 100644 index 14003432b3..0000000000 --- a/sources/tech/20181113 The alias And unalias Commands Explained With Examples.md +++ /dev/null @@ -1,154 +0,0 @@ -The alias And unalias Commands Explained With Examples -====== - - -You may forget the complex and lengthy Linux commands after certain period of time unless you’re a heavy command line user. Sure, there are a few ways to [**recall the forgotten commands**][1]. You could simply [**save the frequently used commands**][2] and use them on demand. Also, you can [**bookmark the important commands**][3] in your Terminal and use whenever you want. And, of course there is already a built-in **“history”** command available to help you to remember the commands. Another easiest way to remember such long commands is to simply create an alias (shortcut) to them. Not just long commands, you can create alias to any frequently used Linux commands for easier repeated invocation. By this approach, you don’t need to memorize those commands anymore. In this guide, we are going to learn about **alias** and **unalias** commands with examples in Linux. - -### The alias command - -The **alias** command is used to run any command or set of commands (inclusive of many options, arguments) with a user-defined string. The string could be a simple name or abbreviations for the commands regardless of how complex the original commands are. You can use the aliases as the way you use the normal Linux commands. The alias command comes preinstalled in shells, including BASH, Csh, Ksh and Zsh etc. - -The general syntax of alias command is: - -``` -alias [alias-name[=string]...] -``` - -Let us go ahead and see some examples. - -**List aliases** - -You might already have aliases in your system. Some applications may create the aliases automatically when you install them. To view the list of existing aliases, run: - -``` -$ alias -``` - -or, - -``` -$ alias -p -``` - -I have the following aliases in my Arch Linux system. - -``` -alias betty='/home/sk/betty/main.rb' -alias ls='ls --color=auto' -alias pbcopy='xclip -selection clipboard' -alias pbpaste='xclip -selection clipboard -o' -alias update='newsbeuter -r && sudo pacman -Syu' -``` - -**Create a new alias** - -Like I already said, you don’t need to memorize the lengthy and complex commands. You don’t even need to run long commands over and over. Just create an alias to the command with easily recognizable name and run it whenever you want. Let us say, you want to use this command often. - -``` -$ du -h --max-depth=1 | sort -hr -``` - -This command finds which sub-directories consume how much disk size in the current working directory. This command is bit long. Instead of remembering the whole command, we can easily create an alias like below: - -``` -$ alias du='du -h --max-depth=1 | sort -hr' -``` - -Here, **du** is the alias name. You can use any name to the alias to easily remember it later. - -You can either use single or double quotes when creating an alias. It makes no difference. - -Now you can just run the alias (i.e **du** in our case) instead of the full command. Both will produce the same result. - -The aliases will expire with the current shell session. They will be gone once you log out of the current session. In order to make the aliases permanent, you need to add them in your shell’s configuration file. - -On BASH shell, edit **~/.bashrc** file: - -``` -$ nano ~/.bashrc -``` - -Add the aliases one by one: - - -Save and quit the file. Then, update the changes by running the following command: - -``` -$ source ~/.bashrc -``` - -Now, the aliases are persistent across sessions. - -On ZSH, you need to add the aliases in **~/.zshrc** file. Similarly, add your aliases in **~/.config/fish/config.fish** file if you use Fish shell. - -**Viewing a specific aliased command** - -As I mentioned earlier, you can view the list of all aliases in your system using ‘alias’ command. If you want to view the command associated with a given alias, for example ‘du’, just run: - -``` -$ alias du -alias du='du -h --max-depth=1 | sort -hr' -``` - -As you can see, the above command display the command associated with the word ‘du’. - -For more details about alias command, refer the man pages: - -``` -$ man alias -``` - -### The unalias command - -As the name says, the **unalias** command simply removes the aliases in your system. The typical syntax of unalias command is: - -``` -unalias -``` - -To remove an aliased command, for example ‘du’ which we created earlier, simply run: - -``` -$ unalias du -``` - -The unalias command not only removes the alias from the current session, but also remove them permanently from your shell’s configuration file. - -Another way to remove an alias is to create a new alias with same name. - -To remove all aliases from the current session, use **-a** flag: - -``` -$ unalias -a -``` - -For more details, refer man pages. - -``` -$ man unalias -``` - -Creating aliases to complex and lengthy commands will save you some time if you run those commands over and over. Now it is your time to create aliases the frequently used commands. - -And, that’s all for now. Hope this helps. More good stuffs to come. Stay tuned! - -Cheers! - - - --------------------------------------------------------------------------------- - -via: https://www.ostechnix.com/the-alias-and-unalias-commands-explained-with-examples/ - -作者：[SK][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://www.ostechnix.com/author/sk/ -[b]: https://github.com/lujun9972 -[1]: https://www.ostechnix.com/easily-recall-forgotten-linux-commands/ -[2]: https://www.ostechnix.com/save-commands-terminal-use-demand/ -[3]: https://www.ostechnix.com/bookmark-linux-commands-easier-repeated-invocation/ diff --git a/sources/tech/20181114 How to use systemd-nspawn for Linux system recovery.md b/sources/tech/20181114 How to use systemd-nspawn for Linux system recovery.md new file mode 100644 index 0000000000..3355436cc3 --- /dev/null +++ b/sources/tech/20181114 How to use systemd-nspawn for Linux system recovery.md @@ -0,0 +1,148 @@ +How to use systemd-nspawn for Linux system recovery +====== +Tap into systemd's ability to launch containers to repair a damaged system's root filesystem. + + +For as long as GNU/Linux systems have existed, system administrators have needed to recover from root filesystem corruption, accidental configuration changes, or other situations that kept the system from booting into a "normal" state. + +Linux distributions typically offer one or more menu options at boot time (for example, in the GRUB menu) that can be used for rescuing a broken system; typically they boot the system into a single-user mode with most system services disabled. In the worst case, the user could modify the kernel command line in the bootloader to use the standard shell as the init (PID 1) process. This method is the most complex and fraught with complications, which can lead to frustration and lost time when a system needs rescuing. + +Most importantly, these methods all assume that the damaged system has a physical console of some sort, but this is no longer a given in the age of cloud computing. Without a physical console, there are few (if any) options to influence the boot process this way. Even physical machines may be small, embedded devices that don't offer an easy-to-use console, and finding the proper serial port cables and adapters and setting up a serial terminal emulator, all to use a serial console port while dealing with an emergency, is often complicated. + +When another system (of the same architecture and generally similar configuration) is available, a common technique to simplify the repair process is to extract the storage device(s) from the damaged system and connect them to the working system as secondary devices. With physical systems, this is usually straightforward, but most cloud computing platforms can also support this since they allow the root storage volume of the damaged instance to be mounted on another instance. + +Once the root filesystem is attached to another system, addressing filesystem corruption is straightforward using **fsck** and other tools. Addressing configuration mistakes, broken packages, or other issues can be more complex since they require mounting the filesystem and locating and changing the correct configuration files or databases. + +### Using systemd + +Before **[**systemd**][1]** , editing configuration files with a text editor was a practical way to correct a configuration. Locating the necessary files and understanding their contents may be a separate challenge, which is beyond the scope of this article. + +When the GNU/Linux system uses **systemd** though, many configuration changes are best made using the tools it provides—enabling and disabling services, for example, requires the creation or removal of symbolic links in various locations. The **systemctl** tool is used to make these changes, but using it requires a **systemd** instance to be running and listening (on D-Bus) for requests. When the root filesystem is mounted as an additional filesystem on another machine, the running **systemd** instance can't be used to make these changes. + +Manually launching the target system's **systemd** is not practical either, since it is designed to be the PID 1 process on a system and manage all other processes, which would conflict with the already-running instance on the system used for the repairs. + +Thankfully, **systemd** has the ability to launch containers, fully encapsulated GNU/Linux systems with their own PID 1 and environment that utilize various namespace features offered by the Linux kernel. Unlike tools like Docker and Rocket, **systemd** doen't require a container image to launch a container; it can launch one rooted at any point in the existing filesystem. This is done using the **systemd-nspawn** tool, which will create the necessary system namespaces and launch the initial process in the container, then provide a console in the container. In contrast to **chroot** , which only changes the apparent root of the filesystem, this type of container will have a separate filesystem namespace, suitable filesystems mounted on **/dev** , **/run** , and **/proc** , and a separate process namespace and IPC namespaces. Consult the **systemd-nspawn** [man page][2] to learn more about its capabilities. + +### An example to show how it works + +In this example, the storage device containing the damaged system's root filesystem has been attached to a running system, where it appears as **/dev/vdc**. The device name will vary based on the number of existing storage devices, the type of device, and the method used to connect it to the system. The root filesystem could use the entire storage device or be in a partition within the device; since the most common (simple) configuration places the root filesystem in the device's first partition, this example will use **/dev/vdc1.** Make sure to replace the device name in the commands below with your system's correct device name. + +The damaged root filesystem may also be more complex than a single filesystem on a device; it may be a volume in an LVM volume set or on a set of devices combined into a software RAID device. In these cases, the necessary steps to compose and activate the logical device holding the filesystem must be performed before it will be available for mounting. Again, those steps are beyond the scope of this article. + +#### Prerequisites + +First, ensure the **systemd-nspawn** tool is installed—most GNU/Linux distributions don't install it by default. It's provided by the **systemd-container** package on most distributions, so use your distribution's package manager to install that package. The instructions in this example were tested using Debian 9 but should work similarly on any modern GNU/Linux distribution. + +Using the commands below will almost certainly require root permissions, so you'll either need to log in as root, use **sudo** to obtain a shell with root permissions, or prefix each of the commands with **sudo**. + +#### Verify and mount the fileystem + +First, use **fsck** to verify the target filesystem's structures and content: + +``` +$ fsck /dev/vdc1 +``` + +If it finds any problems with the filesystem, answer the questions appropriately to correct them. If the filesystem is sufficiently damaged, it may not be repairable, in which case you'll have to find other ways to extract its contents. + +Now, create a temporary directory and mount the target filesystem onto that directory: + +``` +$ mkdir /tmp/target-rescue +$ mount /dev/vdc1 /tmp/target-rescue +``` + +With the filesystem mounted, launch a container with that filesystem as its root filesystem: + +``` +$ systemd-nspawn --directory /tmp/target-rescue --boot -- --unit rescue.target +``` + +The command-line arguments for launching the container are: + + * **\--directory /tmp/target-rescue** provides the path of the container's root filesystem. + * **\--boot** searches for a suitable init program in the container's root filesystem and launches it, passing parameters from the command line to it. In this example, the target system also uses **systemd** as its PID 1 process, so the remaining parameters are intended for it. If the target system you are repairing uses any other tool as its PID 1 process, you'll need to adjust the parameters accordingly. + * **\--** separates parameters for **systemd-nspawn** from those intended for the container's PID 1 process. + * **\--unit rescue.target** tells **systemd** in the container the name of the target it should try to reach during the boot process. In order to simplify the rescue operations in the target system, boot it into "rescue" mode rather than into its normal multi-user mode. + + + +If all goes well, you should see output that looks similar to this: + +``` +Spawning container target-rescue on /tmp/target-rescue. +Press ^] three times within 1s to kill container. +systemd 232 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN) +Detected virtualization systemd-nspawn. +Detected architecture arm. + +Welcome to Debian GNU/Linux 9 (Stretch)! + +Set hostname to . +Failed to install release agent, ignoring: No such file or directory +[ OK ] Reached target Swap. +[ OK ] Listening on Journal Socket (/dev/log). +[ OK ] Started Dispatch Password Requests to Console Directory Watch. +[ OK ] Reached target Encrypted Volumes. +[ OK ] Created slice System Slice. + Mounting POSIX Message Queue File System... +[ OK ] Listening on Journal Socket. + Starting Set the console keyboard layout... + Starting Restore / save the current clock... + Starting Journal Service... + Starting Remount Root and Kernel File Systems... +[ OK ] Mounted POSIX Message Queue File System. +[ OK ] Started Journal Service. +[ OK ] Started Remount Root and Kernel File Systems. + Starting Flush Journal to Persistent Storage... +[ OK ] Started Restore / save the current clock. +[ OK ] Started Flush Journal to Persistent Storage. +[ OK ] Started Set the console keyboard layout. +[ OK ] Reached target Local File Systems (Pre). +[ OK ] Reached target Local File Systems. + Starting Create Volatile Files and Directories... +[ OK ] Started Create Volatile Files and Directories. +[ OK ] Reached target System Time Synchronized. + Starting Update UTMP about System Boot/Shutdown... +[ OK ] Started Update UTMP about System Boot/Shutdown. +[ OK ] Reached target System Initialization. +[ OK ] Started Rescue Shell. +[ OK ] Reached target Rescue Mode. + Starting Update UTMP about System Runlevel Changes... +[ OK ] Started Update UTMP about System Runlevel Changes. +You are in rescue mode. After logging in, type "journalctl -xb" to view +system logs, "systemctl reboot" to reboot, "systemctl default" or ^D to +boot into default mode. +Give root password for maintenance +(or press Control-D to continue): +``` + +In this output, you can see **systemd** launching as the init process in the container and detecting that it is being run inside a container so it can adjust its behavior appropriately. Various unit files are started to bring the container to a usable state, then the target system's root password is requested. You can enter the root password here if you want a shell prompt with root permissions, or you can press **Ctrl+D** to allow the startup process to continue, which will display a normal console login prompt. + +When you have completed the necessary changes to the target system, press **Ctrl+]** three times in rapid succession; this will terminate the container and return you to your original shell. From there, you can clean up by unmounting the target system's filesystem and removing the temporary directory: + +``` +$ umount /tmp/target-rescue +$ rmdir /tmp/target-rescue +``` + +That's it! You can now remove the target system's storage device(s) and return them to the target system. + +The idea to use **systemd-nspawn** this way, especially the **\--boot parameter** , came from [a question][3] posted on StackExchange. Thanks to Shibumi and kirbyfan64sos for providing useful answers to this question! + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/11/systemd-nspawn-system-recovery + +作者：[Kevin P.Fleming][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/kpfleming +[b]: https://github.com/lujun9972 +[1]: https://www.freedesktop.org/wiki/Software/systemd/ +[2]: https://www.freedesktop.org/software/systemd/man/systemd-nspawn.html +[3]: https://unix.stackexchange.com/questions/457819/running-systemd-utilities-like-systemctl-under-an-nspawn diff --git a/sources/tech/20181115 11 Things To Do After Installing elementary OS 5 Juno.md b/sources/tech/20181115 11 Things To Do After Installing elementary OS 5 Juno.md new file mode 100644 index 0000000000..5e23c6e5c4 --- /dev/null +++ b/sources/tech/20181115 11 Things To Do After Installing elementary OS 5 Juno.md @@ -0,0 +1,260 @@ +11 Things To Do After Installing elementary OS 5 Juno +====== +I’ve been using [elementary OS 5 Juno][1] for over a month and it has been an amazing experience. It is easily the [best Mac OS inspired Linux distribution][2] and one of the [best Linux distribution for beginners][3]. + +However, you will need to take care of a couple of things after installing it. +In this article, we will discuss the most important things that you need to do after installing [elementary OS][4] 5 Juno. + +### Things to do after installing elementary OS 5 Juno + +![Things to do after installing elementary OS Juno][5] + +Things I mentioned in this list are from my personal experience and preference. Of course, you are not restricted to these few things. You can explore and tweak the system as much as you like. However, if you follow (some of) these recommendations, things might be smoother for you. + +#### 1.Run a System Update + +![terminal showing system updates in elementary os 5 Juno][6] + +Even when you download the latest version of a distribution – it is always recommended to check for the latest System updates. You might have a quick fix for an annoying bug, or, maybe there’s an important security patch that you shouldn’t ignore. So, no matter what – you should always ensure that you have everything up-to-date. + +To do that, you need to type in the following command in the terminal: + +``` +sudo apt-get update +``` + +#### 2\. Set Window Hotcorner + +![][7] + +You wouldn’t notice the minimize button for a window. So, how do you do it? + +Well, you can just bring up the dock and click the app icon again to minimize it or press **Windows key + H** as a shortcut to minimize the active window. + +But, I’ll recommend something way more easy and intuitive. Maybe you already knew it, but for the users who were unaware of the “ **hotcorners** ” feature, here’s what it does: + +Whenever you hover the cursor to any of the 4 corners of the window, you can set a preset action to happen when you do that. For example, when you move your cursor to the **left corner** of the screen you get the **multi-tasking view** to switch between apps – which acts like a “gesture“. + +In order to utilize the functionality, you can follow the steps below: + + 1. Head to the System Settings. + 2. Click on the “ **Desktop** ” option (as shown in the image above). + 3. Next, select the “ **Hot Corner** ” section (as shown in the image below). + 4. Depending on what corner you prefer, choose an appropriate action (refer to the image below – that’s what I personally prefer as my settings) + + + +#### 3\. Install Multimedia codecs + +I’ve tried playing MP3/MP4 files – it just works fine. However, there are a lot of file formats when it comes to multimedia. + +So, just to be able to play almost every format of multimedia, you should install the codecs. Here’s what you need to enter in the terminal: + +To get certain proprietary codecs: + +``` +sudo apt install ubuntu-restricted-extras +``` + +To specifically install [Libav][8]: + +``` +sudo apt install libavcodec-extra +``` + +To install a codec in order to facilitate playing video DVDs: + +``` +sudo apt install libdvd-pkg +``` + +#### 4\. Install GDebi + +You don’t get to install .deb files by just double-clicking it on elementary OS 5 Juno. It just does not let you do that. + +So, you need an additional tool to help you install .deb files. + +We’ll recommend you to use **GDebi**. I prefer it because it lets you know about the dependencies even before trying to install it – that way – you can be sure about what you need in order to correctly install an application. + +Simply install GDebi and open any .deb files by performing a right-click on them **open in GDebi Package Installer.** + +To install it, type in the following command: + +``` +sudo apt install gdebi +``` + +#### 5\. Add a PPA for your Favorite App + +Yes, elementary OS 5 Juno now supports PPA (unlike its previous version). So, you no longer need to enable the support for PPAs explicitly. + +Just grab a PPA and add it via terminal to install something you like. + +#### 6\. Install Essential Applications + +If you’re a Linux power user, you already know what you want and where to get it, but if you’re new to this Linux distro and looking out for some applications to have installed, I have a few recommendations: + +**Steam app** : If you’re a gamer, this is a must-have app. You just need to type in a single command to install it: + +``` +sudo apt install steam +``` + +**GIMP** : It is the best photoshop alternative across every platform. Get it installed for every type of image manipulation: + +``` +sudo apt install gimp +``` + +**Wine** : If you want to install an application that only runs on Windows, you can try using Wine to run such Windows apps here on Linux. To install, follow the command: + +``` +sudo apt install wine-stable +``` + +**qBittorrent** : If you prefer downloading Torrent files, you should have this installed as your Torrent client. To install it, enter the following command: + +``` +sudo apt install qbittorrent +``` + +**Flameshot** : You can obviously utilize the default screenshot tool to take screenshots. But, if you want to instantly share your screenshots and the ability to annotate – install flameshot. Here’s how you can do that: + +``` +sudo apt install flameshot +``` + +**Chrome/Firefox: **The default browser isn’t much useful. So, you should install Chrome/Firefox – as per your choice. + +To install chrome, enter the command: + +``` +sudo apt install chromium-browser +``` + +To install Firefox, enter: + +``` +sudo apt install firefox +``` + +These are some of the most common applications you should definitely have installed. For the rest, you should browse through the App Center or the Flathub to install your favorite applications. + +#### 7\. Install Flatpak (Optional) + +It’s just my personal recommendation – I find flatpak to be the preferred way to install apps on any Linux distro I use. + +You can try it and learn more about it at its [official website][9]. + +To install flatpak, type in: + +``` +sudo apt install flatpak +``` + +After you are done installing flatpak, you can directly head to [Flathub][10] to install some of your favorite apps and you will also find the command/instruction to install it via the terminal. + +In case you do not want to launch the browser, you can search for your app by typing in (example – finding Discord and installing it): + +``` +flatpak search discord flathub +``` + +After gettting the application ID, you can proceed installing it by typing in: + +``` +flatpak install flathub com.discordapp.Discord +``` + +#### 8\. Enable the Night Light + +![Night Light in elementary OS Juno][11] + +You might have installed Redshift as per our recommendation for [elemantary OS 0.4 Loki][12] to filter the blue light to avoid straining our eyes- but you do not need any 3rd party tool anymore. + +It comes baked in as the “ **Night Light** ” feature. + +You just head to System Settings and click on “ **Displays** ” (as shown in the image above). + +Select the **Night Light** section and activate it with your preferred settings. + +#### 9\. Install NVIDIA driver metapackage (for NVIDIA GPUs) + +![Nvidia drivers in elementary OS juno][13] + +The NVIDIA driver metapackage should be listed right at the App Center – so you can easily the NVIDIA driver. + +However, it’s not the latest driver version – I have version **390.77** installed and it’s performing just fine. + +If you want the latest version for Linux, you should check out NVIDIA’s [official download page][14]. + +Also, if you’re curious about the version installed, just type in the following command: + +``` +nvidia-smi +``` + +#### 10\. Install TLP for Advanced Power Management + +We’ve said it before. And, we’ll still recommend it. + +If you want to manage your background tasks/activity and prevent overheating of your system – you should install TLP. + +It does not offer a GUI, but you don’t have to bother. You just install it and let it manage whatever it takes to prevent overheating. + +It’s very helpful for laptop users. + +To install, type in: + +``` +supo apt install tlp tlp-rdw +``` + +#### 11\. Perform visual customizations + +![][15] + +If you need to change the look of your Linux distro, you can install GNOME tweaks tool to get the options. In order to install the tweak tool, type in: + +``` +sudo apt install gnome-tweaks +``` + +Once you install it, head to the application launcher and search for “Tweaks”, you’ll find something like this: + +Here, you can select the icon, theme, wallpaper, and you’ll also be able to tweak a couple more options that’s not limited to the visual elements. + +### Wrapping Up + +It’s the least you should do after installing elementary OS 5 Juno. However, considering that elementary OS 5 Juno comes with numerous new features – you can explore a lot more new things as well. + +Let us know what you did first after installing elementary OS 5 Juno and how’s your experience with it so far? + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/things-to-do-after-installing-elementary-os-5-juno/ + +作者：[Ankush Das][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://itsfoss.com/author/ankush/ +[b]: https://github.com/lujun9972 +[1]: https://itsfoss.com/elementary-os-juno-features/ +[2]: https://itsfoss.com/macos-like-linux-distros/ +[3]: https://itsfoss.com/best-linux-beginners/ +[4]: https://elementary.io/ +[5]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2018/11/things-to-do-after-installing-elementary-os-juno.jpeg?ssl=1 +[6]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/11/elementary-os-system-update.jpg?ssl=1 +[7]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/11/elementary-os-hotcorners.jpg?ssl=1 +[8]: https://libav.org/ +[9]: https://flatpak.org/ +[10]: https://flathub.org/home +[11]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2018/11/elementary-os-night-light.jpg?ssl=1 +[12]: https://itsfoss.com/things-to-do-after-installing-elementary-os-loki/ +[13]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2018/11/elementary-os-nvidia-metapackage.jpg?ssl=1 +[14]: https://www.nvidia.com/Download/index.aspx +[15]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2018/11/elementary-os-gnome-tweaks.jpg?ssl=1 diff --git a/sources/tech/20181119 Arch-Wiki-Man - A Tool to Browse The Arch Wiki Pages As Linux Man Page from Offline.md b/sources/tech/20181119 Arch-Wiki-Man - A Tool to Browse The Arch Wiki Pages As Linux Man Page from Offline.md new file mode 100644 index 0000000000..9e1ee18be7 --- /dev/null +++ b/sources/tech/20181119 Arch-Wiki-Man - A Tool to Browse The Arch Wiki Pages As Linux Man Page from Offline.md @@ -0,0 +1,214 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: subject: (Arch-Wiki-Man – A Tool to Browse The Arch Wiki Pages As Linux Man Page from Offline) +[#]: via: (https://www.2daygeek.com/arch-wiki-man-a-tool-to-browse-the-arch-wiki-pages-as-linux-man-page-from-offline/) +[#]: author: ([Prakash Subramanian](https://www.2daygeek.com/author/prakash/)) +[#]: url: ( ) + +Arch-Wiki-Man – A Tool to Browse The Arch Wiki Pages As Linux Man Page from Offline +====== + +Getting internet is not a big deal now a days, however there will be a limitation on technology. + +I was really surprise to see the technology growth but in the same time there will be fall in everywhere. + +Whenever you search anything about other Linux distributions most of the time you will get a third party links in the first place but for Arch Linux every time you would get the Arch Wiki page for your results. + +As Arch Wiki has most of the solution other than third party websites. + +As of now, you might used web browser to get a solution for your Arch Linux system but you no need to do the same for now. + +There is a solution is available in command line to perform this action much faster way and the utility called arch-wiki-man. If you are Arch Linux lover, i would suggest you to read **[Arch Linux Post Installation guide][1]** which helps you to tweak your system for day to day use. + +### What is arch-wiki-man? + +[arch-wiki-man][2] tool allows user to search the arch wiki pages right from the command line (CLI) instantly without internet connection. It allows user to access and search an entire wiki pages as a Linux man page. + +Also, you no need to switch to GUI. Updates are pushed automatically every two days so, your local copy of the Arch Wiki pages will be upto date. The tool name is `awman`. awman stands for Arch Wiki Man. + +We had already wrote similar kind of topic called **[Arch Wiki Command Line Utility][3]** (arch-wiki-cli) which allows user search Arch Wiki from command line but make sure you should have internet to use this utility. + +### How to Install arch-wiki-man tool? + +arch-wiki-man utility is available in AUR repository so, we need to use AUR helper to install it. There are many AUR helper is available and we had wrote an article about **[Yaourt AUR helper][4]** and **[Packer AUR helper][5]** which are very famous AUR helper. + +``` +$ yaourt -S arch-wiki-man + +or + +$ packer -S arch-wiki-man +``` + +Alternatively we can install it using npm package manager. Make sure, you should have installed **[NodeJS][6]** on your system. If so, run the following command to install it. + +``` +$ npm install -g arch-wiki-man +``` + +### How to Update the local Arch Wiki copy? + +As updated previously, updates are pushed automatically every two days and it can be done by running the following command. + +``` +$ sudo awman-update +[sudo] password for daygeek: +[email protected] /usr/lib/node_modules/arch-wiki-man +└── [email protected] + +arch-wiki-md-repo has been successfully updated or reinstalled. +``` + +awman-update is faster and more convenient method to get the update. However, you can get the updates by reinstalling this package using the following command. + +``` +$ yaourt -S arch-wiki-man + +or + +$ packer -S arch-wiki-man +``` + +### How to Use Arch Wiki from command line? + +It’s very simple interface and easy to use. To search anything, just run `awman` followed by the search term. The general syntax is as follow. + +``` +$ awman Search-Term +``` + +### How to Search Multiple Matches? + +If you would like to list all the results titles comes with `installation` string, run the following command format. If the output comes with multiple results then you will get a selection menu to navigate each item. + +``` +$ awman installation +``` + +![][8] + +Detailed page screenshot. +![][9] + +### Search a given string in Titles & Descriptions + +The `-d` or `--desc-search` option allow users to search a given string in titles and descriptions. + +``` +$ awman -d mirrors + +or + +$ awman --desc-search mirrors +? Select an article: (Use arrow keys) +❯ [1/3] Mirrors: Related articles + [2/3] DeveloperWiki-NewMirrors: Contents + [3/3] Powerpill: Powerpill is a pac +``` + +### Search a given string in Contents + +The `-k` or `--apropos` option allow users to search a given string in content as well. Make a note, this option significantly slower your search as this scan entire wiki page content. + +``` +$ awman -k openjdk + +or + +$ awman --apropos openjdk +? Select an article: (Use arrow keys) +❯ [1/26] Hadoop: Related articles + [2/26] XDG Base Directory support: Related articles + [3/26] Steam-Game-specific troubleshooting: See Steam/Troubleshooting first. + [4/26] Android: Related articles + [5/26] Elasticsearch: Elasticsearch is a search engine based on Lucene. It provides a distributed, mul.. + [6/26] LibreOffice: Related articles + [7/26] Browser plugins: Related articles +(Move up and down to reveal more choices) +``` + +### Open the search results in a web browser + +The `-w` or `--web` option allow users to open the search results in a web browser. + +``` +$ awman -w AUR helper + +or + +$ awman --web AUR helper +``` + +![][10] + +### Search in other languages + +The `-w` or `--web` option allow users to open the search results in a web browser. To see a list of supported language, run the following command. + +``` +$ awman --list-languages +arabic +bulgarian +catalan +chinesesim +chinesetrad +croatian +czech +danish +dutch +english +esperanto +finnish +greek +hebrew +hungarian +indonesian +italian +korean +lithuanian +norwegian +polish +portuguese +russian +serbian +slovak +spanish +swedish +thai +ukrainian +``` + +Run the awman command with your preferred language to see the results with different language other than English. + +``` +$ awman -l chinesesim deepin +``` + +![][11] + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/arch-wiki-man-a-tool-to-browse-the-arch-wiki-pages-as-linux-man-page-from-offline/ + +作者：[Prakash Subramanian][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.2daygeek.com/author/prakash/ +[b]: https://github.com/lujun9972 +[1]: https://www.2daygeek.com/arch-linux-post-installation-30-things-to-do-after-installing-arch-linux/ +[2]: https://github.com/greg-js/arch-wiki-man +[3]: https://www.2daygeek.com/search-arch-wiki-website-command-line-terminal/ +[4]: https://www.2daygeek.com/install-yaourt-aur-helper-on-arch-linux/ +[5]: https://www.2daygeek.com/install-packer-aur-helper-on-arch-linux/ +[6]: https://www.2daygeek.com/install-nodejs-on-ubuntu-centos-debian-fedora-mint-rhel-opensuse/ +[7]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[8]: https://www.2daygeek.com/wp-content/uploads/2018/11/arch-wiki-man-%E2%80%93-A-Tool-to-Browse-The-Arch-Wiki-Pages-As-Linux-Man-page-from-Offline-1.png +[9]: https://www.2daygeek.com/wp-content/uploads/2018/11/arch-wiki-man-%E2%80%93-A-Tool-to-Browse-The-Arch-Wiki-Pages-As-Linux-Man-page-from-Offline-2.png +[10]: https://www.2daygeek.com/wp-content/uploads/2018/11/arch-wiki-man-%E2%80%93-A-Tool-to-Browse-The-Arch-Wiki-Pages-As-Linux-Man-page-from-Offline-3.png +[11]: https://www.2daygeek.com/wp-content/uploads/2018/11/arch-wiki-man-%E2%80%93-A-Tool-to-Browse-The-Arch-Wiki-Pages-As-Linux-Man-page-from-Offline-4.png diff --git a/sources/tech/20181122 Getting started with Jenkins X.md b/sources/tech/20181122 Getting started with Jenkins X.md new file mode 100644 index 0000000000..1c2aab6903 --- /dev/null +++ b/sources/tech/20181122 Getting started with Jenkins X.md @@ -0,0 +1,148 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: subject: (Getting started with Jenkins X) +[#]: via: (https://opensource.com/article/18/11/getting-started-jenkins-x) +[#]: author: (Dave Johnson https://opensource.com/users/snoopdave) +[#]: url: ( ) + +Getting started with Jenkins X +====== +Jenkins X provides continuous integration, automated testing, and continuous delivery to Kubernetes. + + +[Jenkins X][1] is an open source system that offers software developers continuous integration, automated testing, and continuous delivery, known as CI/CD, in Kubernetes. Jenkins X-managed projects get a complete CI/CD process with a Jenkins pipeline that builds and packages project code for deployment to Kubernetes and access to pipelines for promoting projects to staging and production environments. + +Developers are already benefiting from running "classic" open source Jenkins and CloudBees Jenkins on Kubernetes, thanks in part to the Jenkins Kubernetes plugin, which allows you to dynamically spin-up Kubernetes pods to run Jenkins build agents. Jenkins X adds what's missing from Jenkins: comprehensive support for continuous delivery and managing the promotion of projects to preview, staging, and production environments running in Kubernetes. + +This article is a high-level explanation of how Jenkins X works; it assumes you have some knowledge of Kubernetes and classic Jenkins. + +### What you get with Jenkins X + +If you're running on one of the major cloud providers (Amazon Elastic Container Service for Kubernetes, Google Kubernetes Engine, or Microsoft Azure Kubernetes Service), installing and deploying Jenkins X is easy. Download the Jenkins X command-line interface and run the **jx create cluster** command. You'll be prompted for the necessary information and, if you take the defaults, Jenkins X will create a starter-size Kubernetes cluster and install Jenkins X. + +When you deploy Jenkins X, a number of services are put in motion to watch your Git repositories and respond by building, testing, and promoting your applications to staging, production, and other environments you define. Jenkins X also deploys a set of supporting services, including [Jenkins][2], [Docker Registry][3], [Chart Museum][4], and [Monocular][5] to manage [Helm][6] charts, and [Nexus][7], which serves as a Maven and npm repository. + +The Jenkins X deployment also creates two Git repositories, one for your staging environment and one for production. These are in addition to the Git repositories you use to manage your project source code. Jenkins X uses these repositories to manage what is deployed to each environment, and promotions are done via Git pull requests (PRs)—this approach is known as [GitOps][8]. Each repository contains a Helm chart that specifies the applications to be deployed to the corresponding environment. Each repository also has a Jenkins pipeline to handle promotions. + +### Creating a new project with Jenkins X + +To create a new project with Jenkins X, use the **jx create quickstart** command. If you don't specify any options, jx will prompt you to select a project name and a platform—which can be just about anything. SpringBoot, Go, Python, Node, ASP.NET, Rust, Angular, and React are all supported, and the list keeps growing. Once you have chosen your project name and platform, Jenkins X will: + + * Create a new project that includes a "hello-world"-style web project + * Add the appropriate type of makefile or build script for the chosen platform + * Add a Jenkinsfile to manage promotions to staging and production environments + * Add a Dockerfile and Helm charts, created via [Draft][9] + * Add a [Skaffold][10] configuration for deploying the application to Kubernetes + * Create a Git repository and push the new project code there + + + +Next, a webhook from Git will notify Jenkins X that a project changed, and it will run your project's Jenkins pipeline to build and push your Docker image and Helm charts. + +Finally, the pipeline will submit a PR to the staging environment's Git repository with the changes needed to promote the application. + +Once the PR is merged, the staging pipeline will run to apply those changes and do the promotion. A couple of minutes after creating your project, you'll have end-to-end CI/CD, and your project will be running in staging and available for use. + +![Developer commits changes, project deployed to staging][12] + +Developer commits changes, project deployed to the staging environment. + +The figure above illustrates the repositories, registries, and pipelines and how they interact in a Jenkins X promotion to staging. Here are the steps: + + 1. The developer commits and pushes the change to the project's Git repository + 2. Jenkins X is notified and runs the project's Jenkins pipeline in a Docker image that includes the project's language and supporting frameworks + 3. The project pipeline builds, tests, and pushes the project's Helm chart to Chart Museum and its Docker image to the registry + 4. The project pipeline creates a PR with changes needed to add the project to the staging environment + 5. Jenkins X automatically merges the PR to Master + 6. Jenkins X is notified and runs the staging pipeline + 7. The staging pipeline runs Helm, which deploys the environment, pulling Helm charts from Chart Museum and Docker images from the Docker registry. Kubernetes creates the project's resources, typically a pod, service, and ingress. + + + +### Importing your existing projects into Jenkins X + +**jx import** , Jenkins X adds the things needed for your project to be deployed to Kubernetes and participate in CI/CD. It will add a Jenkins pipeline, Helm charts, and a Skaffold configuration for deploying the application to Kubernetes. Jenkins X will create a Git repository and push the changes there. Next, a webhook from Git will notify Jenkins X that a project changed, and promotion to staging will happen as described above for new projects. + +### Promoting your project to production + +When you import a project via, Jenkins X adds the things needed for your project to be deployed to Kubernetes and participate in CI/CD. It will add a Jenkins pipeline, Helm charts, and a Skaffold configuration for deploying the application to Kubernetes. Jenkins X will create a Git repository and push the changes there. Next, a webhook from Git will notify Jenkins X that a project changed, and promotion to staging will happen as described above for new projects. + +To promote a version of your project to the production environment, use the **jx promote** command. This command will prepare a Git PR that contains the Helm chart changes needed to deploy into the production environment and submit this request to the production environment's Git repository. Once the request is manually approved, Jenkins X will run the production pipeline to deploy your project via Helm. + +![Promoting project to production][14] + +Developer promotes the project to production. + +This figure illustrates the repositories, registries, and pipelines and how they interact in a Jenkins X promotion to production. Here are the steps: + + 1. The developer runs the **jx promote** command to promote a project to production + 2. Jenkins X creates a PR with changes needed to add the project to the production environment + 3. The developer manually approves the PR, and it is merged to Master + 4. Jenkins X is notified and runs the production pipeline + 5. The production pipeline runs Helm, which deploys the environment, pulling Helm charts from Chart Museum and Docker images from the Docker registry. Kubernetes creates the project's resources, typically a pod, service, and ingress. + + + +### Other features of Jenkins X + +Other interesting and appealing features of Jenkins X include: + +#### Preview environments + +When you create a PR to add a new feature to your project, you can ask Jenkins X to create a preview environment so you can make your new feature available for preview and testing before the PR is merged. + +#### Extensions + +It is possible to create extensions to Jenkins X. An extension is code that runs at specific times in the CI/CD process. An extension can provide code that runs when the extension is installed, uninstalled, as well as before and after each pipeline. + +#### Serverless Jenkins + +Instead of running the Jenkins web application, which continually consumes CPU and memory resources, you can run Jenkins only when you need it. During the past year, the Jenkins community created a version of Jenkins that can run classic Jenkins pipelines via the command line with the configuration defined by code instead of HTML forms. + +This capability is now available in Jenkins X. When you create a Jenkins X cluster, you can choose to use Serverless Jenkins. If you do, Jenkins X will deploy [Prow][15] to handle webhooks from GitHub and [Knative][16] to run Jenkins pipelines. + +### Jenkins X limitations + +Jenkins X also has some limitations that should be considered: + + * **Jenkins X is currently limited to projects that use Git:** Jenkins X is opinionated about CI/CD and assumes everybody wants to run and deploy software to Kubernetes and everybody is happy to use Git for source code and defining environments. Also, the Serverless Jenkins feature currently works only with GitHub. + * **Jenkins X is limited to Kubernetes:** It is true that Jenkins X can run automated builds, testing, and continuous integration for any type of software, but the continuous delivery part targets a Kubernetes namespace managed by Jenkins X. + * **Jenkins X requires cluster-admin level Kubernetes access:** Jenkins X needs cluster-admin access so it can define and manage a Kubernetes custom resource definition. Hopefully, this is a temporary limitation, because it could be a show-stopper for some. + + + +### Conclusions + +Jenkins X looks to be a good way to implement CI/CD for Kubernetes, and I'm looking forward to putting it to the test in production. Using Jenkins X is also a good way to learn about some useful open source tools for deploying to Kubernetes, including Helm, Draft, Skaffold, Prow, and more. These are things you might want to use even if you decide Jenkins X is not for you. If you're deploying to Kubernetes, take Jenkins X for a spin. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/11/getting-started-jenkins-x + +作者：[Dave Johnson][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/snoopdave +[b]: https://github.com/lujun9972 +[1]: https://jenkins-x.io/ +[2]: https://jenkins.io/ +[3]: https://docs.docker.com/registry/ +[4]: https://github.com/helm/chartmuseum +[5]: https://github.com/helm/monocular +[6]: https://helm.sh +[7]: https://www.sonatype.com/nexus-repository-oss +[8]: https://www.weave.works/blog/gitops-operations-by-pull-request +[9]: https://draft.sh/ +[10]: https://github.com/GoogleContainerTools/skaffold +[11]: /file/414941 +[12]: https://opensource.com/sites/default/files/uploads/jenkinsx_fig1.png (Developer commits changes, project deployed to staging) +[13]: /file/414946 +[14]: https://opensource.com/sites/default/files/uploads/jenkinsx_fig2.png (Promoting project to production) +[15]: https://github.com/kubernetes/test-infra/tree/master/prow +[16]: https://cloud.google.com/knative/ diff --git a/sources/tech/20181123 Three SSH GUI Tools for Linux.md b/sources/tech/20181123 Three SSH GUI Tools for Linux.md new file mode 100644 index 0000000000..9691a737ca --- /dev/null +++ b/sources/tech/20181123 Three SSH GUI Tools for Linux.md @@ -0,0 +1,176 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: subject: (Three SSH GUI Tools for Linux) +[#]: via: (https://www.linux.com/blog/learn/intro-to-linux/2018/11/three-ssh-guis-linux) +[#]: author: (Jack Wallen https://www.linux.com/users/jlwallen) +[#]: url: ( ) + +Three SSH GUI Tools for Linux +====== + + + +At some point in your career as a Linux administrator, you’re going to use Secure Shell (SSH) to remote into a Linux server or desktop. Chances are, you already have. In some instances, you’ll be SSH’ing into multiple Linux servers at once. In fact, Secure Shell might well be one of the most-used tools in your Linux toolbox. Because of this, you’ll want to make the experience as efficient as possible. For many admins, nothing is as efficient as the command line. However, there are users out there who do prefer a GUI tool, especially when working from a desktop machine to remote into and work on a server. + +If you happen to prefer a good GUI tool, you’ll be happy to know there are a couple of outstanding graphical tools for SSH on Linux. Couple that with a unique terminal window that allows you to remote into multiple machines from the same window, and you have everything you need to work efficiently. Let’s take a look at these three tools and find out if one (or more) of them is perfectly apt to meet your needs. + +I’ll be demonstrating these tools on [Elementary OS][1], but they are all available for most major distributions. + +### PuTTY + +Anyone that’s been around long enough knows about [PuTTY][2]. In fact, PuTTY is the de facto standard tool for connecting, via SSH, to Linux servers from the Windows environment. But PuTTY isn’t just for Windows. In fact, from withing the standard repositories, PuTTY can also be installed on Linux. PuTTY’s feature list includes: + + * Saved sessions. + + * Connect via IP address or hostname. + + * Define alternative SSH port. + + * Connection type definition. + + * Logging. + + * Options for keyboard, bell, appearance, connection, and more. + + * Local and remote tunnel configuration + + * Proxy support + + * X11 tunneling support + + + + +The PuTTY GUI is mostly a way to save SSH sessions, so it’s easier to manage all of those various Linux servers and desktops you need to constantly remote into and out of. Once you’ve connected, from PuTTY to the Linux server, you will have a terminal window in which to work. At this point, you may be asking yourself, why not just work from the terminal window? For some, the convenience of saving sessions does make PuTTY worth using. + +Installing PuTTY on Linux is simple. For example, you could issue the command on a Debian-based distribution: + +``` +sudo apt-get install -y putty +``` + +Once installed, you can either run the PuTTY GUI from your desktop menu or issue the command putty. In the PuTTY Configuration window (Figure 1), type the hostname or IP address in the HostName (or IP address) section, configure the port (if not the default 22), select SSH from the connection type, and click Open. + +![PuTTY Connection][4] + +Figure 1: The PuTTY Connection Configuration Window. + +[Used with permission][5] + +Once the connection is made, you’ll then be prompted for the user credentials on the remote server (Figure 2). + +![log in][7] + +Figure 2: Logging into a remote server with PuTTY. + +[Used with permission][5] + +To save a session (so you don’t have to always type the remote server information), fill out the IP address (or hostname), configure the port and connection type, and then (before you click Open), type a name for the connection in the top text area of the Saved Sessions section, and click Save. This will then save the configuration for the session. To then connect to a saved session, select it from the saved sessions window, click Load, and then click Open. You should then be prompted for the remote credentials on the remote server. + +### EasySSH + +Although [EasySSH][8] doesn’t offer the amount of configuration options found in PuTTY, it’s (as the name implies) incredibly easy to use. One of the best features of EasySSH is that it offers a tabbed interface, so you can have multiple SSH connections open and quickly switch between them. Other EasySSH features include: + + * Groups (so you can group tabs for an even more efficient experience). + + * Username/password save. + + * Appearance options. + + * Local and remote tunnel support. + + + + +Install EasySSH on a Linux desktop is simple, as the app can be installed via flatpak (which does mean you must have Flatpak installed on your system). Once flatpak is installed, add EasySSH with the commands: + +``` +sudo flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo + +sudo flatpak install flathub com.github.muriloventuroso.easyssh +``` + +Run EasySSH with the command: + +``` +flatpak run com.github.muriloventuroso.easyssh +``` + +The EasySSH app will open, where you can click the + button in the upper left corner. In the resulting window (Figure 3), configure your SSH connection as required. + +![Adding a connection][10] + +Figure 3: Adding a connection in EasySSH is simple. + +[Used with permission][5] + +Once you’ve added the connection, it will appear in the left navigation of the main window (Figure 4). + +![EasySSH][12] + +Figure 4: The EasySSH main window. + +[Used with permission][5] + +To connect to a remote server in EasySSH, select it from the left navigation and then click the Connect button (Figure 5). + +![Connecting][14] + +Figure 5: Connecting to a remote server with EasySSH. + +[Used with permission][5] + +The one caveat with EasySSH is that you must save the username and password in the connection configuration (otherwise the connection will fail). This means anyone with access to the desktop running EasySSH can remote into your servers without knowing the passwords. Because of this, you must always remember to lock your desktop screen any time you are away (and make sure to use a strong password). The last thing you want is to have a server vulnerable to unwanted logins. + +### Terminator + +Terminator is not actually an SSH GUI. Instead, Terminator functions as a single window that allows you to run multiple terminals (and even groups of terminals) at once. Effectively you can open Terminator, split the window vertical and horizontally (until you have all the terminals you want), and then connect to all of your remote Linux servers by way of the standard SSH command (Figure 6). + +![Terminator][16] + +Figure 6: Terminator split into three different windows, each connecting to a different Linux server. + +[Used with permission][5] + +To install Terminator, issue a command like: + +### sudo apt-get install -y terminator + +Once installed, open the tool either from your desktop menu or from the command terminator. With the window opened, you can right-click inside Terminator and select either Split Horizontally or Split Vertically. Continue splitting the terminal until you have exactly the number of terminals you need, and then start remoting into those servers. +The caveat to using Terminator is that it is not a standard SSH GUI tool, in that it won’t save your sessions or give you quick access to those servers. In other words, you will always have to manually log into your remote Linux servers. However, being able to see your remote Secure Shell sessions side by side does make administering multiple remote machines quite a bit easier. + +Few (But Worthwhile) Options + +There aren’t a lot of SSH GUI tools available for Linux. Why? Because most administrators prefer to simply open a terminal window and use the standard command-line tools to remotely access their servers. However, if you have a need for a GUI tool, you have two solid options and one terminal that makes logging into multiple machines slightly easier. Although there are only a few options for those looking for an SSH GUI tool, those that are available are certainly worth your time. Give one of these a try and see for yourself. + +-------------------------------------------------------------------------------- + +via: https://www.linux.com/blog/learn/intro-to-linux/2018/11/three-ssh-guis-linux + +作者：[Jack Wallen][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.linux.com/users/jlwallen +[b]: https://github.com/lujun9972 +[1]: https://elementary.io/ +[2]: https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html +[3]: https://www.linux.com/files/images/sshguis1jpg +[4]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/ssh_guis_1.jpg?itok=DiNTz_wO (PuTTY Connection) +[5]: https://www.linux.com/licenses/category/used-permission +[6]: https://www.linux.com/files/images/sshguis2jpg +[7]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/ssh_guis_2.jpg?itok=4ORsJlz3 (log in) +[8]: https://github.com/muriloventuroso/easyssh +[9]: https://www.linux.com/files/images/sshguis3jpg +[10]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/ssh_guis_3.jpg?itok=bHC2zlda (Adding a connection) +[11]: https://www.linux.com/files/images/sshguis4jpg +[12]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/ssh_guis_4.jpg?itok=hhJzhRIg (EasySSH) +[13]: https://www.linux.com/files/images/sshguis5jpg +[14]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/ssh_guis_5.jpg?itok=piFEFYTQ (Connecting) +[15]: https://www.linux.com/files/images/sshguis6jpg +[16]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/ssh_guis_6.jpg?itok=-kYl6iSE (Terminator) diff --git a/sources/tech/20181124 14 Best ASCII Games for Linux That are Insanely Good.md b/sources/tech/20181124 14 Best ASCII Games for Linux That are Insanely Good.md new file mode 100644 index 0000000000..094467698b --- /dev/null +++ b/sources/tech/20181124 14 Best ASCII Games for Linux That are Insanely Good.md @@ -0,0 +1,335 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: subject: (14 Best ASCII Games for Linux That are Insanely Good) +[#]: via: (https://itsfoss.com/best-ascii-games/) +[#]: author: (Ankush Das https://itsfoss.com/author/ankush/) +[#]: url: ( ) + +14 Best ASCII Games for Linux That are Insanely Good +====== + +Text-based or should I say [terminal-based games][1] were very popular a decade back – when you didn’t have visual masterpieces like God Of War, Red Dead Redemption 2 or Spiderman. + +Of course, the Linux platform has its share of good games – but not always the “latest and greatest”. But, there are some ASCII games out there – to which you can never turn your back on. + +I’m not sure if you’d believe me, some of the ASCII games proved to be very addictive (So, it might take a while for me to resume work on the next article, or I might just get fired? – Help me!) + +Jokes apart, let us take a look at the best ASCII games. + +**Note:** Installing ASCII games could be time-consuming (some might ask you to install additional dependencies or simply won’t work). You might even encounter some ASCII games that require you build from Source. So, we’ve filtered out only the ones that are easy to install/run – without breaking a sweat. + +### Things to do before Running or Installing an ASCII Game + +Some of the ASCII games might require you to install [Simple DirectMedia Layer][2] unless you already have it installed. So, in case, you should install them first before trying to run any of the games mentioned in this article. + +For that, you just need to type in these commands: + +``` +sudo apt install libsdl2-2.0 +``` + +``` +sudo apt install libsdl2_mixer-2.0 +``` + \--args**) over and over. You can document it with a custom domain, adding directives and indexes along the way. + +Here's an example from our **recipe** domain: + +``` +The recipe contains `tomato` and `cilantro`. + +.. rcp:recipe:: TomatoSoup + :contains: tomato cilantro salt pepper + + This recipe is a tasty tomato soup, combine all ingredients + and cook. +``` + +Now that we've defined the recipe **TomatoSoup** , we can reference it anywhere in our documentation using the custom role **refef**. For example: + +``` +You can use the :rcp:reref:`TomatoSoup` recipe to feed your family. +``` + +This enables our recipes to show up in two indices: the first lists all recipes, and the second lists all recipes by ingredient. + +### What's in a domain? + +A Sphinx domain is a specialized container that ties together roles, directives, and indices, among other things. The domain has a name ( **rcp** ) to address its components in the documentation source. It announces its existence to Sphinx in the **setup()** method of the package. From there, Sphinx can find roles and directives, since these are part of the domain. + +This domain also serves as the central catalog of objects in this sample. Using initial data, it defines two variables, **objects** and **obj2ingredient**. These contain a list of all objects defined (all recipes) and a hash that maps a canonical ingredient name to the list of objects. + +``` +initial_data = { + 'objects': [], # object list + 'obj2ingredient': {}, # ingredient -> [objects] +} +``` + +The way we name objects is common across our extension. For each object created, the canonical name is **rcp. . **, where **< typename>** is the Python type of the object, and **< objectname>** is the name the documentation writer gives the object. This enables the extension to use different object types that share the same name. + +Having a canonical name and central place for our objects is a huge advantage. Both our indices and our cross-referencing code use this feature. + +### Custom roles and directives + +In our example, **.. rcp:recipe::** indicates a custom directive. You might think it's overly specific to create custom syntax for these items, but it illustrates the degree of customization you can get in Sphinx. This provides rich markup that structures documents and leads to better docs. Specialization allows us to extract information from our docs. + +Our definition for this directive will provide minimal formatting, but it will be functional. + +``` +class RecipeNode(ObjectDescription): + """A custom node that describes a recipe.""" + + required_arguments = 1 + + option_spec = { + 'contains': rst.directives.unchanged_required + } +``` + +For this directive, **required_arguments** tells Sphinx to expect one parameter, the recipe name. **option_spec** lists the optional arguments, including their names. Finally, **has_content** specifies that there will be more reStructured Text as a child to this node. + +We also implement multiple methods: + + * **handle_signature()** implements parsing the signature of the directive and passes on the object's name and type to its superclass + * **add_taget_and_index()** adds a target (to link to) and an entry to the index for this node + + + +### Creating indices + +Both **IngredientIndex** and **RecipeIndex** are derived from Sphinx's **Index** class. They implement custom logic to generate a tuple of values that define the index. Note that **RecipeIndex** is a degenerate index that has only one entry. Extending it to cover more object types—and moving from a **RecipeDomain** to a **CookbookDomain** —is not yet part of the code. + +Both indices use the method **generate()** to do their work. This method combines the information from our domain, sorts it, and returns it in a list structure that will be accepted by Sphinx. See the [Sphinx Domain API][3] page for more information. + +The first time you visit the Domain API page, you may be a little overwhelmed by the structure. But our ingredient index is just a list of tuples, like **('tomato', 'TomatoSoup', 'test', 'rec-TomatoSoup',...)**. + +### Referencing recipes + +Adding cross-references is not difficult (but it's also not a given). Add an **XRefRole** to the domain and implement the method **resolve_xref()**. Having a custom role to reference a type allows us to unambiguously reference any object, even if two objects have the same name. If you look at the parameters of **resolve_xref()** in **Domain** , you'll see **typ** and **target**. These define the cross-reference type and its target name. We'll use **target** to resolve our destination from our domain's **objects** because we currently have only one type of node. + +We can add the cross-reference role to **RecipeDomain** in the following way: + +``` +roles = { + 'reref': XRefRole() +} +``` + +There's nothing for us to implement. Defining a working **resolve_xref()** and attaching an **XRefRole** to the domain is all you need to do. + + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/11/building-custom-workflows-sphinx + +作者：[Mark Meyer][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/ofosos +[b]: https://github.com/lujun9972 +[1]: http://www.sphinx-doc.org/en/master/ +[2]: https://github.com/ofosos/sphinxrecipes +[3]: https://www.sphinx-doc.org/en/master/extdev/domainapi.html#sphinx.domains.Index.generate diff --git a/sources/tech/20181128 How to test your network with PerfSONAR.md b/sources/tech/20181128 How to test your network with PerfSONAR.md new file mode 100644 index 0000000000..9e9e66ef62 --- /dev/null +++ b/sources/tech/20181128 How to test your network with PerfSONAR.md @@ -0,0 +1,148 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: subject: (How to test your network with PerfSONAR) +[#]: via: (https://opensource.com/article/18/11/how-test-your-network-perfsonar) +[#]: author: (Jessica Repka https://opensource.com/users/jrepka) +[#]: url: ( ) + +How to test your network with PerfSONAR +====== +Set up a single-node configuration to measure your network performance. + + +[PerfSONAR][1] is a network measurement toolkit collection for testing and sharing data on end-to-end network perfomance. + +The overall benefit of using network measurement tools like PerfSONAR is they can find issues before they become a large elephant in the room that nobody wants to talk about. Specifically, with the right answers from the right tools, patching can become more stringent, network traffic can be shaped to speed connections across the board, and the network infrastructure design can be improved. + +PerfSONAR is licensed under the open source Apache 2.0 license, which makes it more affordable than most tools that do this type of analysis, a key advantage given constrained network infrastructure budgets. + +### PerfSONAR versions + +Several versions of PerfSONAR are available: + + * **Perfsonar-tools:** The command line client version meant for on-demand testing. + * **Perfsonar-testpoint:** Adds automated testing and central management testing to PerfSONAR-tools. It has an archiving feature, but the archive must be set to an external node. + * **Perfsonar-core:** Includes everything in the testpoint software, but with local rather than external archiving. + * **Perfsonar-toolkit:** The core software; it includes a web UI with systemwide security settings. + * **Perfsonar-centralmanagement:** A completely separate version of PerfSONAR that uses mass grids of nodes to display results. It also has a feature to push out task templates to every node that is sending measurements back to the central host. + + + +This tutorial will use **PerfSonar-toolkit** ; the tools used in this software include [iPerf, iPerf3][2], and [OWAMP][3]. + +### Requirements + + * **Recommended operating system:** CentOS/RHEL7 + * **ISO:** [Downloading][4] the full installation ISO is the fastest way to get the software up and running. While there is a [Debian version][5], it is much harder and more complicated to use. + * **Minimum hardware requirements:** 2 cores and 4GB RAM + * **Recommended hardware:** 200GB HDD, 4 cores, 6GB of RAM + + + +### Installing and configuring PerfSONAR + +The installation is a quick CentOS install where you pick your timezone and configuration for the hard drive and user. I suggest using hard drive autoconfiguration, as you only need to choose "Install Toolkit" and follow the prompts from there. + +Select your language. + +Select a destination. + +After base installation, you see the Linux login screen. + +After you log in, you are prompted to create a user ID and password to log into PerfSONAR's web frontend—make sure to remember your login information. + +You're also asked to disable SSH access for root and create a new user for sudo; just follow the steps to create the new user. + +You can use a provisioning service to automatically provide an IP address and hostname. Otherwise, you will have to set the hostname (optional) and configure the IP address. + +### Log into the web frontend + +Once the base configuration is complete, you can log into the web frontend via ** Scribus Online Manual + ++
+ + + ++ +
+
+
++``` + +For more options and usage details, refer the help secion: + +``` +$ hyperfine --help +``` + +And, that’s all for now. If you ever be in a situation where you need to benchmark similar and alternative programs, these tools might help to compare how they performs and share the details with your peers and colleagues. + +More good stuffs to come. Stay tuned! + +Cheers! + + + +-------------------------------------------------------------------------------- + +via: https://www.ostechnix.com/how-to-benchmark-linux-commands-and-programs-from-commandline/ + +作者：[SK][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.ostechnix.com/author/sk/ +[b]: https://github.com/lujun9972 +[1]: https://www.ostechnix.com/some-alternatives-to-top-command-line-utility-you-might-want-to-know/ +[2]: https://aur.archlinux.org/packages/hyperfine +[3]: https://www.ostechnix.com/yay-found-yet-another-reliable-aur-helper/ +[4]: https://github.com/sharkdp/hyperfine/releases diff --git a/sources/tech/20181212 TLP - An Advanced Power Management Tool That Improve Battery Life On Linux Laptop.md b/sources/tech/20181212 TLP - An Advanced Power Management Tool That Improve Battery Life On Linux Laptop.md new file mode 100644 index 0000000000..e1e6a7f25e --- /dev/null +++ b/sources/tech/20181212 TLP - An Advanced Power Management Tool That Improve Battery Life On Linux Laptop.md @@ -0,0 +1,745 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (TLP – An Advanced Power Management Tool That Improve Battery Life On Linux Laptop) +[#]: via: (https://www.2daygeek.com/tlp-increase-optimize-linux-laptop-battery-life/) +[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/) + +TLP – An Advanced Power Management Tool That Improve Battery Life On Linux Laptop +====== + +Laptop battery is highly optimized for Windows OS, that i had realized when i was using Windows OS in my laptop but it’s not same for Linux. + +Over the years Linux has improved a lot for battery optimization but still we need make some necessary things to improve laptop battery life in Linux. + +When i think about battery life, i got few options for that but i felt TLP is a better solutions for me so, i’m going with it. + +In this tutorial we are going to discuss about TLP in details to improve battery life. + +We had written three articles previously in our site about **[laptop battery saving utilities][1]** for Linux **[PowerTOP][2]** and **[Battery Charging State][3]**. + +### What is TLP? + +[TLP][4] is a free opensource advanced power management tool that improve your battery life without making any configuration change. + +Since it comes with a default configuration already optimized for battery life, so you may just install and forget it. + +Also, it is highly customizable to fulfill your specific requirements. TLP is a pure command line tool with automated background tasks. It does not contain a GUI. + +TLP runs on every laptop brand. Setting the battery charge thresholds is available for IBM/Lenovo ThinkPads only. + +All TLP settings are stored in `/etc/default/tlp`. The default configuration provides optimized power saving out of the box. + +The following TLP settings is available for customization and you need to make the necessary changes accordingly if you want it. + +### TLP Features + + * Kernel laptop mode and dirty buffer timeouts + * Processor frequency scaling including “turbo boost” / “turbo core” + * Limit max/min P-state to control power dissipation of the CPU + * HWP energy performance hints + * Power aware process scheduler for multi-core/hyper-threading + * Processor performance versus energy savings policy (x86_energy_perf_policy) + * Hard disk advanced power magement level (APM) and spin down timeout (per disk) + * AHCI link power management (ALPM) with device blacklist + * PCIe active state power management (PCIe ASPM) + * Runtime power management for PCI(e) bus devices + * Radeon graphics power management (KMS and DPM) + * Wifi power saving mode + * Power off optical drive in drive bay + * Audio power saving mode + * I/O scheduler (per disk) + * USB autosuspend with device blacklist/whitelist (input devices excluded automatically) + * Enable or disable integrated wifi, bluetooth or wwan devices upon system startup and shutdown + * Restore radio device state on system startup (from previous shutdown). + * Radio device wizard: switch radios upon network connect/disconnect and dock/undock + * Disable Wake On LAN + * Integrated WWAN and bluetooth state is restored after suspend/hibernate + * Untervolting of Intel processors – requires kernel with PHC-Patch + * Battery charge thresholds – ThinkPads only + * Recalibrate battery – ThinkPads only + + + +### How to Install TLP in Linux + +TLP package is available in most of the distributions official repository so, use the distributions **[Package Manager][5]** to install it. + +For **`Fedora`** system, use **[DNF Command][6]** to install TLP. + +``` +$ sudo dnf install tlp tlp-rdw +``` + +ThinkPads require an additional packages. + +``` +$ sudo dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm +$ sudo dnf install http://repo.linrunner.de/fedora/tlp/repos/releases/tlp-release.fc$(rpm -E %fedora).noarch.rpm +$ sudo dnf install akmod-tp_smapi akmod-acpi_call kernel-devel +``` + +Install smartmontool to display S.M.A.R.T. data in tlp-stat. + +``` +$ sudo dnf install smartmontools +``` + +For **`Debian/Ubuntu`** systems, use **[APT-GET Command][7]** or **[APT Command][8]** to install TLP. + +``` +$ sudo apt install tlp tlp-rdw +``` + +ThinkPads require an additional packages. + +``` +$ sudo apt-get install tp-smapi-dkms acpi-call-dkms +``` + +Install smartmontool to display S.M.A.R.T. data in tlp-stat. + +``` +$ sudo apt-get install smartmontools +``` + +When the official package becomes outdated for Ubuntu based systems then use the following PPA repository which provides an up-to-date version. Run the following commands to install TLP using the PPA. + +``` +$ sudo apt-get install tlp tlp-rdw +``` + +For **`Arch Linux`** based systems, use **[Pacman Command][9]** to install TLP. + +``` +$ sudo pacman -S tlp tlp-rdw +``` + +ThinkPads require an additional packages. + +``` +$ pacman -S tp_smapi acpi_call +``` + +Install smartmontool to display S.M.A.R.T. data in tlp-stat. + +``` +$ sudo pacman -S smartmontools +``` + +Enable TLP & TLP-Sleep service on boot for Arch Linux based systems. + +``` +$ sudo systemctl enable tlp.service +$ sudo systemctl enable tlp-sleep.service +``` + +You should also mask the following services to avoid conflicts and assure proper operation of TLP’s radio device switching options for Arch Linux based systems. + +``` +$ sudo systemctl mask systemd-rfkill.service +$ sudo systemctl mask systemd-rfkill.socket +``` + +For **`RHEL/CentOS`** systems, use **[YUM Command][10]** to install TLP. + +``` +$ sudo yum install tlp tlp-rdw +``` + +Install smartmontool to display S.M.A.R.T. data in tlp-stat. + +``` +$ sudo yum install smartmontools +``` + +For **`openSUSE Leap`** system, use **[Zypper Command][11]** to install TLP. + +``` +$ sudo zypper install TLP +``` + +Install smartmontool to display S.M.A.R.T. data in tlp-stat. + +``` +$ sudo zypper install smartmontools +``` + +After successfully TLP installed, use the following command to start the service. + +``` +$ systemctl start tlp.service +``` + +To show battery information. + +``` +$ sudo tlp-stat -b +or +$ sudo tlp-stat --battery + +--- TLP 1.1 -------------------------------------------- + ++++ Battery Status +/sys/class/power_supply/BAT0/manufacturer = SMP +/sys/class/power_supply/BAT0/model_name = L14M4P23 +/sys/class/power_supply/BAT0/cycle_count = (not supported) +/sys/class/power_supply/BAT0/energy_full_design = 60000 [mWh] +/sys/class/power_supply/BAT0/energy_full = 48850 [mWh] +/sys/class/power_supply/BAT0/energy_now = 48850 [mWh] +/sys/class/power_supply/BAT0/power_now = 0 [mW] +/sys/class/power_supply/BAT0/status = Full + +Charge = 100.0 [%] +Capacity = 81.4 [%] +``` + +To show disk information. + +``` +$ sudo tlp-stat -d +or +$ sudo tlp-stat --disk + +--- TLP 1.1 -------------------------------------------- + ++++ Storage Devices +/dev/sda: + Model = WDC WD10SPCX-24HWST1 + Firmware = 02.01A02 + APM Level = 128 + Status = active/idle + Scheduler = mq-deadline + + Runtime PM: control = on, autosuspend_delay = (not available) + + SMART info: + 4 Start_Stop_Count = 18787 + 5 Reallocated_Sector_Ct = 0 + 9 Power_On_Hours = 606 [h] + 12 Power_Cycle_Count = 1792 + 193 Load_Cycle_Count = 25775 + 194 Temperature_Celsius = 31 [°C] + + ++++ AHCI Link Power Management (ALPM) +/sys/class/scsi_host/host0/link_power_management_policy = med_power_with_dipm +/sys/class/scsi_host/host1/link_power_management_policy = med_power_with_dipm +/sys/class/scsi_host/host2/link_power_management_policy = med_power_with_dipm +/sys/class/scsi_host/host3/link_power_management_policy = med_power_with_dipm + ++++ AHCI Host Controller Runtime Power Management +/sys/bus/pci/devices/0000:00:17.0/ata1/power/control = on +/sys/bus/pci/devices/0000:00:17.0/ata2/power/control = on +/sys/bus/pci/devices/0000:00:17.0/ata3/power/control = on +/sys/bus/pci/devices/0000:00:17.0/ata4/power/control = on +``` + +To show PCI device information. + +``` +$ sudo tlp-stat -e +or +$ sudo tlp-stat --pcie + +--- TLP 1.1 -------------------------------------------- + ++++ Runtime Power Management +Device blacklist = (not configured) +Driver blacklist = amdgpu nouveau nvidia radeon pcieport + +/sys/bus/pci/devices/0000:00:00.0/power/control = auto (0x060000, Host bridge, skl_uncore) +/sys/bus/pci/devices/0000:00:01.0/power/control = auto (0x060400, PCI bridge, pcieport) +/sys/bus/pci/devices/0000:00:02.0/power/control = auto (0x030000, VGA compatible controller, i915) +/sys/bus/pci/devices/0000:00:14.0/power/control = auto (0x0c0330, USB controller, xhci_hcd) +/sys/bus/pci/devices/0000:00:16.0/power/control = auto (0x078000, Communication controller, mei_me) +/sys/bus/pci/devices/0000:00:17.0/power/control = auto (0x010601, SATA controller, ahci) +/sys/bus/pci/devices/0000:00:1c.0/power/control = auto (0x060400, PCI bridge, pcieport) +/sys/bus/pci/devices/0000:00:1c.2/power/control = auto (0x060400, PCI bridge, pcieport) +/sys/bus/pci/devices/0000:00:1c.3/power/control = auto (0x060400, PCI bridge, pcieport) +/sys/bus/pci/devices/0000:00:1d.0/power/control = auto (0x060400, PCI bridge, pcieport) +/sys/bus/pci/devices/0000:00:1f.0/power/control = auto (0x060100, ISA bridge, no driver) +/sys/bus/pci/devices/0000:00:1f.2/power/control = auto (0x058000, Memory controller, no driver) +/sys/bus/pci/devices/0000:00:1f.3/power/control = auto (0x040300, Audio device, snd_hda_intel) +/sys/bus/pci/devices/0000:00:1f.4/power/control = auto (0x0c0500, SMBus, i801_smbus) +/sys/bus/pci/devices/0000:01:00.0/power/control = auto (0x030200, 3D controller, nouveau) +/sys/bus/pci/devices/0000:07:00.0/power/control = auto (0x080501, SD Host controller, sdhci-pci) +/sys/bus/pci/devices/0000:08:00.0/power/control = auto (0x028000, Network controller, iwlwifi) +/sys/bus/pci/devices/0000:09:00.0/power/control = auto (0x020000, Ethernet controller, r8168) +/sys/bus/pci/devices/0000:0a:00.0/power/control = auto (0x010802, Non-Volatile memory controller, nvme) +``` + +To show graphics card information. + +``` +$ sudo tlp-stat -g +or +$ sudo tlp-stat --graphics + +--- TLP 1.1 -------------------------------------------- + ++++ Intel Graphics +/sys/module/i915/parameters/enable_dc = -1 (use per-chip default) +/sys/module/i915/parameters/enable_fbc = 1 (enabled) +/sys/module/i915/parameters/enable_psr = 0 (disabled) +/sys/module/i915/parameters/modeset = -1 (use per-chip default) +``` + +To show Processor information. + +``` +$ sudo tlp-stat -p +or +$ sudo tlp-stat --processor + +--- TLP 1.1 -------------------------------------------- + ++++ Processor +CPU model = Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz + +/sys/devices/system/cpu/cpu0/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu0/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu1/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu1/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu1/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu1/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu1/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu1/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu1/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu2/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu2/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu2/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu2/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu2/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu2/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu2/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu3/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu3/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu3/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu3/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu3/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu3/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu3/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu4/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu4/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu4/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu4/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu4/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu4/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu4/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu5/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu5/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu5/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu5/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu5/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu5/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu5/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu6/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu6/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu6/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu6/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu6/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu6/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu6/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu7/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu7/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu7/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu7/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu7/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu7/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu7/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/intel_pstate/min_perf_pct = 22 [%] +/sys/devices/system/cpu/intel_pstate/max_perf_pct = 100 [%] +/sys/devices/system/cpu/intel_pstate/no_turbo = 0 +/sys/devices/system/cpu/intel_pstate/turbo_pct = 33 [%] +/sys/devices/system/cpu/intel_pstate/num_pstates = 28 + +x86_energy_perf_policy: program not installed. + +/sys/module/workqueue/parameters/power_efficient = Y +/proc/sys/kernel/nmi_watchdog = 0 + ++++ Undervolting +PHC kernel not available. +``` + +To show system data information. + +``` +$ sudo tlp-stat -s +or +$ sudo tlp-stat --system + +--- TLP 1.1 -------------------------------------------- + ++++ System Info +System = LENOVO Lenovo ideapad Y700-15ISK 80NV +BIOS = CDCN35WW +Release = "Manjaro Linux" +Kernel = 4.19.6-1-MANJARO #1 SMP PREEMPT Sat Dec 1 12:21:26 UTC 2018 x86_64 +/proc/cmdline = BOOT_IMAGE=/boot/vmlinuz-4.19-x86_64 root=UUID=69d9dd18-36be-4631-9ebb-78f05fe3217f rw quiet resume=UUID=a2092b92-af29-4760-8e68-7a201922573b +Init system = systemd +Boot mode = BIOS (CSM, Legacy) + ++++ TLP Status +State = enabled +Last run = 11:04:00 IST, 596 sec(s) ago +Mode = battery +Power source = battery +``` + +To show temperatures and fan speed information. + +``` +$ sudo tlp-stat -t +or +$ sudo tlp-stat --temp + +--- TLP 1.1 -------------------------------------------- + ++++ Temperatures +CPU temp = 36 [°C] +Fan speed = (not available) +``` + +To show USB device data information. + +``` +$ sudo tlp-stat -u +or +$ sudo tlp-stat --usb + +--- TLP 1.1 -------------------------------------------- + ++++ USB +Autosuspend = disabled +Device whitelist = (not configured) +Device blacklist = (not configured) +Bluetooth blacklist = disabled +Phone blacklist = disabled +WWAN blacklist = enabled + +Bus 002 Device 001 ID 1d6b:0003 control = auto, autosuspend_delay_ms = 0 -- Linux Foundation 3.0 root hub (hub) +Bus 001 Device 003 ID 174f:14e8 control = auto, autosuspend_delay_ms = 2000 -- Syntek (uvcvideo) +Bus 001 Device 002 ID 17ef:6053 control = on, autosuspend_delay_ms = 2000 -- Lenovo (usbhid) +Bus 001 Device 004 ID 8087:0a2b control = auto, autosuspend_delay_ms = 2000 -- Intel Corp. (btusb) +Bus 001 Device 001 ID 1d6b:0002 control = auto, autosuspend_delay_ms = 0 -- Linux Foundation 2.0 root hub (hub) +``` + +To show warnings. + +``` +$ sudo tlp-stat -w +or +$ sudo tlp-stat --warn + +--- TLP 1.1 -------------------------------------------- + +No warnings detected. +``` + +Status report with configuration and all active settings. + +``` +$ sudo tlp-stat + +--- TLP 1.1 -------------------------------------------- + ++++ Configured Settings: /etc/default/tlp +TLP_ENABLE=1 +TLP_DEFAULT_MODE=AC +TLP_PERSISTENT_DEFAULT=0 +DISK_IDLE_SECS_ON_AC=0 +DISK_IDLE_SECS_ON_BAT=2 +MAX_LOST_WORK_SECS_ON_AC=15 +MAX_LOST_WORK_SECS_ON_BAT=60 +CPU_HWP_ON_AC=balance_performance +CPU_HWP_ON_BAT=balance_power +SCHED_POWERSAVE_ON_AC=0 +SCHED_POWERSAVE_ON_BAT=1 +NMI_WATCHDOG=0 +ENERGY_PERF_POLICY_ON_AC=performance +ENERGY_PERF_POLICY_ON_BAT=power +DISK_DEVICES="sda sdb" +DISK_APM_LEVEL_ON_AC="254 254" +DISK_APM_LEVEL_ON_BAT="128 128" +SATA_LINKPWR_ON_AC="med_power_with_dipm max_performance" +SATA_LINKPWR_ON_BAT="med_power_with_dipm max_performance" +AHCI_RUNTIME_PM_TIMEOUT=15 +PCIE_ASPM_ON_AC=performance +PCIE_ASPM_ON_BAT=powersave +RADEON_POWER_PROFILE_ON_AC=default +RADEON_POWER_PROFILE_ON_BAT=low +RADEON_DPM_STATE_ON_AC=performance +RADEON_DPM_STATE_ON_BAT=battery +RADEON_DPM_PERF_LEVEL_ON_AC=auto +RADEON_DPM_PERF_LEVEL_ON_BAT=auto +WIFI_PWR_ON_AC=off +WIFI_PWR_ON_BAT=on +WOL_DISABLE=Y +SOUND_POWER_SAVE_ON_AC=0 +SOUND_POWER_SAVE_ON_BAT=1 +SOUND_POWER_SAVE_CONTROLLER=Y +BAY_POWEROFF_ON_AC=0 +BAY_POWEROFF_ON_BAT=0 +BAY_DEVICE="sr0" +RUNTIME_PM_ON_AC=on +RUNTIME_PM_ON_BAT=auto +RUNTIME_PM_DRIVER_BLACKLIST="amdgpu nouveau nvidia radeon pcieport" +USB_AUTOSUSPEND=0 +USB_BLACKLIST_BTUSB=0 +USB_BLACKLIST_PHONE=0 +USB_BLACKLIST_PRINTER=1 +USB_BLACKLIST_WWAN=1 +RESTORE_DEVICE_STATE_ON_STARTUP=0 + ++++ System Info +System = LENOVO Lenovo ideapad Y700-15ISK 80NV +BIOS = CDCN35WW +Release = "Manjaro Linux" +Kernel = 4.19.6-1-MANJARO #1 SMP PREEMPT Sat Dec 1 12:21:26 UTC 2018 x86_64 +/proc/cmdline = BOOT_IMAGE=/boot/vmlinuz-4.19-x86_64 root=UUID=69d9dd18-36be-4631-9ebb-78f05fe3217f rw quiet resume=UUID=a2092b92-af29-4760-8e68-7a201922573b +Init system = systemd +Boot mode = BIOS (CSM, Legacy) + ++++ TLP Status +State = enabled +Last run = 11:04:00 IST, 684 sec(s) ago +Mode = battery +Power source = battery + ++++ Processor +CPU model = Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz + +/sys/devices/system/cpu/cpu0/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu0/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu1/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu1/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu1/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu1/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu1/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu1/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu1/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu2/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu2/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu2/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu2/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu2/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu2/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu2/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu3/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu3/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu3/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu3/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu3/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu3/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu3/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu4/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu4/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu4/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu4/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu4/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu4/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu4/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu5/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu5/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu5/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu5/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu5/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu5/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu5/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu6/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu6/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu6/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu6/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu6/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu6/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu6/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/cpu7/cpufreq/scaling_driver = intel_pstate +/sys/devices/system/cpu/cpu7/cpufreq/scaling_governor = powersave +/sys/devices/system/cpu/cpu7/cpufreq/scaling_available_governors = performance powersave +/sys/devices/system/cpu/cpu7/cpufreq/scaling_min_freq = 800000 [kHz] +/sys/devices/system/cpu/cpu7/cpufreq/scaling_max_freq = 3500000 [kHz] +/sys/devices/system/cpu/cpu7/cpufreq/energy_performance_preference = balance_power +/sys/devices/system/cpu/cpu7/cpufreq/energy_performance_available_preferences = default performance balance_performance balance_power power + +/sys/devices/system/cpu/intel_pstate/min_perf_pct = 22 [%] +/sys/devices/system/cpu/intel_pstate/max_perf_pct = 100 [%] +/sys/devices/system/cpu/intel_pstate/no_turbo = 0 +/sys/devices/system/cpu/intel_pstate/turbo_pct = 33 [%] +/sys/devices/system/cpu/intel_pstate/num_pstates = 28 + +x86_energy_perf_policy: program not installed. + +/sys/module/workqueue/parameters/power_efficient = Y +/proc/sys/kernel/nmi_watchdog = 0 + ++++ Undervolting +PHC kernel not available. + ++++ Temperatures +CPU temp = 42 [°C] +Fan speed = (not available) + ++++ File System +/proc/sys/vm/laptop_mode = 2 +/proc/sys/vm/dirty_writeback_centisecs = 6000 +/proc/sys/vm/dirty_expire_centisecs = 6000 +/proc/sys/vm/dirty_ratio = 20 +/proc/sys/vm/dirty_background_ratio = 10 + ++++ Storage Devices +/dev/sda: + Model = WDC WD10SPCX-24HWST1 + Firmware = 02.01A02 + APM Level = 128 + Status = active/idle + Scheduler = mq-deadline + + Runtime PM: control = on, autosuspend_delay = (not available) + + SMART info: + 4 Start_Stop_Count = 18787 + 5 Reallocated_Sector_Ct = 0 + 9 Power_On_Hours = 606 [h] + 12 Power_Cycle_Count = 1792 + 193 Load_Cycle_Count = 25777 + 194 Temperature_Celsius = 31 [°C] + + ++++ AHCI Link Power Management (ALPM) +/sys/class/scsi_host/host0/link_power_management_policy = med_power_with_dipm +/sys/class/scsi_host/host1/link_power_management_policy = med_power_with_dipm +/sys/class/scsi_host/host2/link_power_management_policy = med_power_with_dipm +/sys/class/scsi_host/host3/link_power_management_policy = med_power_with_dipm + ++++ AHCI Host Controller Runtime Power Management +/sys/bus/pci/devices/0000:00:17.0/ata1/power/control = on +/sys/bus/pci/devices/0000:00:17.0/ata2/power/control = on +/sys/bus/pci/devices/0000:00:17.0/ata3/power/control = on +/sys/bus/pci/devices/0000:00:17.0/ata4/power/control = on + ++++ PCIe Active State Power Management +/sys/module/pcie_aspm/parameters/policy = powersave + ++++ Intel Graphics +/sys/module/i915/parameters/enable_dc = -1 (use per-chip default) +/sys/module/i915/parameters/enable_fbc = 1 (enabled) +/sys/module/i915/parameters/enable_psr = 0 (disabled) +/sys/module/i915/parameters/modeset = -1 (use per-chip default) + ++++ Wireless +bluetooth = on +wifi = on +wwan = none (no device) + +hci0(btusb) : bluetooth, not connected +wlp8s0(iwlwifi) : wifi, connected, power management = on + ++++ Audio +/sys/module/snd_hda_intel/parameters/power_save = 1 +/sys/module/snd_hda_intel/parameters/power_save_controller = Y + ++++ Runtime Power Management +Device blacklist = (not configured) +Driver blacklist = amdgpu nouveau nvidia radeon pcieport + +/sys/bus/pci/devices/0000:00:00.0/power/control = auto (0x060000, Host bridge, skl_uncore) +/sys/bus/pci/devices/0000:00:01.0/power/control = auto (0x060400, PCI bridge, pcieport) +/sys/bus/pci/devices/0000:00:02.0/power/control = auto (0x030000, VGA compatible controller, i915) +/sys/bus/pci/devices/0000:00:14.0/power/control = auto (0x0c0330, USB controller, xhci_hcd) +/sys/bus/pci/devices/0000:00:16.0/power/control = auto (0x078000, Communication controller, mei_me) +/sys/bus/pci/devices/0000:00:17.0/power/control = auto (0x010601, SATA controller, ahci) +/sys/bus/pci/devices/0000:00:1c.0/power/control = auto (0x060400, PCI bridge, pcieport) +/sys/bus/pci/devices/0000:00:1c.2/power/control = auto (0x060400, PCI bridge, pcieport) +/sys/bus/pci/devices/0000:00:1c.3/power/control = auto (0x060400, PCI bridge, pcieport) +/sys/bus/pci/devices/0000:00:1d.0/power/control = auto (0x060400, PCI bridge, pcieport) +/sys/bus/pci/devices/0000:00:1f.0/power/control = auto (0x060100, ISA bridge, no driver) +/sys/bus/pci/devices/0000:00:1f.2/power/control = auto (0x058000, Memory controller, no driver) +/sys/bus/pci/devices/0000:00:1f.3/power/control = auto (0x040300, Audio device, snd_hda_intel) +/sys/bus/pci/devices/0000:00:1f.4/power/control = auto (0x0c0500, SMBus, i801_smbus) +/sys/bus/pci/devices/0000:01:00.0/power/control = auto (0x030200, 3D controller, nouveau) +/sys/bus/pci/devices/0000:07:00.0/power/control = auto (0x080501, SD Host controller, sdhci-pci) +/sys/bus/pci/devices/0000:08:00.0/power/control = auto (0x028000, Network controller, iwlwifi) +/sys/bus/pci/devices/0000:09:00.0/power/control = auto (0x020000, Ethernet controller, r8168) +/sys/bus/pci/devices/0000:0a:00.0/power/control = auto (0x010802, Non-Volatile memory controller, nvme) + ++++ USB +Autosuspend = disabled +Device whitelist = (not configured) +Device blacklist = (not configured) +Bluetooth blacklist = disabled +Phone blacklist = disabled +WWAN blacklist = enabled + +Bus 002 Device 001 ID 1d6b:0003 control = auto, autosuspend_delay_ms = 0 -- Linux Foundation 3.0 root hub (hub) +Bus 001 Device 003 ID 174f:14e8 control = auto, autosuspend_delay_ms = 2000 -- Syntek (uvcvideo) +Bus 001 Device 002 ID 17ef:6053 control = on, autosuspend_delay_ms = 2000 -- Lenovo (usbhid) +Bus 001 Device 004 ID 8087:0a2b control = auto, autosuspend_delay_ms = 2000 -- Intel Corp. (btusb) +Bus 001 Device 001 ID 1d6b:0002 control = auto, autosuspend_delay_ms = 0 -- Linux Foundation 2.0 root hub (hub) + ++++ Battery Status +/sys/class/power_supply/BAT0/manufacturer = SMP +/sys/class/power_supply/BAT0/model_name = L14M4P23 +/sys/class/power_supply/BAT0/cycle_count = (not supported) +/sys/class/power_supply/BAT0/energy_full_design = 60000 [mWh] +/sys/class/power_supply/BAT0/energy_full = 51690 [mWh] +/sys/class/power_supply/BAT0/energy_now = 50140 [mWh] +/sys/class/power_supply/BAT0/power_now = 12185 [mW] +/sys/class/power_supply/BAT0/status = Discharging + +Charge = 97.0 [%] +Capacity = 86.2 [%] +``` + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/tlp-increase-optimize-linux-laptop-battery-life/ + +作者：[Magesh Maruthamuthu][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.2daygeek.com/author/magesh/ +[b]: https://github.com/lujun9972 +[1]: https://www.2daygeek.com/check-laptop-battery-status-and-charging-state-in-linux-terminal/ +[2]: https://www.2daygeek.com/powertop-monitors-laptop-battery-usage-linux/ +[3]: https://www.2daygeek.com/monitor-laptop-battery-charging-state-linux/ +[4]: https://linrunner.de/en/tlp/docs/tlp-linux-advanced-power-management.html +[5]: https://www.2daygeek.com/category/package-management/ +[6]: https://www.2daygeek.com/dnf-command-examples-manage-packages-fedora-system/ +[7]: https://www.2daygeek.com/apt-get-apt-cache-command-examples-manage-packages-debian-ubuntu-systems/ +[8]: https://www.2daygeek.com/apt-command-examples-manage-packages-debian-ubuntu-systems/ +[9]: https://www.2daygeek.com/pacman-command-examples-manage-packages-arch-linux-system/ +[10]: https://www.2daygeek.com/yum-command-examples-manage-packages-rhel-centos-systems/ +[11]: https://www.2daygeek.com/zypper-command-examples-manage-packages-opensuse-system/ diff --git a/sources/tech/20181213 Podman and user namespaces- A marriage made in heaven.md b/sources/tech/20181213 Podman and user namespaces- A marriage made in heaven.md new file mode 100644 index 0000000000..adc14c6111 --- /dev/null +++ b/sources/tech/20181213 Podman and user namespaces- A marriage made in heaven.md @@ -0,0 +1,145 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Podman and user namespaces: A marriage made in heaven) +[#]: via: (https://opensource.com/article/18/12/podman-and-user-namespaces) +[#]: author: (Daniel J Walsh https://opensource.com/users/rhatdan) + +Podman and user namespaces: A marriage made in heaven +====== +Learn how to use Podman to run containers in separate user namespaces. + + +[Podman][1], part of the [libpod][2] library, enables users to manage pods, containers, and container images. In my last article, I wrote about [Podman as a more secure way to run containers][3]. Here, I'll explain how to use Podman to run containers in separate user namespaces. + +I have always thought of [user namespace][4], primarily developed by Red Hat's Eric Biederman, as a great feature for separating containers. User namespace allows you to specify a user identifier (UID) and group identifier (GID) mapping to run your containers. This means you can run as UID 0 inside the container and UID 100000 outside the container. If your container processes escape the container, the kernel will treat them as UID 100000. Not only that, but any file object owned by a UID that isn't mapped into the user namespace will be treated as owned by "nobody" (65534, kernel.overflowuid), and the container process will not be allowed access unless the object is accessible by "other" (world readable/writable). + +If you have a file owned by "real" root with permissions [660][5], and the container processes in the user namespace attempt to read it, they will be prevented from accessing it and will see the file as owned by nobody. + +### An example + +Here's how that might work. First, I create a file in my system owned by root. + +``` +$ sudo bash -c "echo Test > /tmp/test" +$ sudo chmod 600 /tmp/test +$ sudo ls -l /tmp/test +-rw-------. 1 root root 5 Dec 17 16:40 /tmp/test +``` + +Next, I volume-mount the file into a container running with a user namespace map 0:100000:5000. + +``` +$ sudo podman run -ti -v /tmp/test:/tmp/test:Z --uidmap 0:100000:5000 fedora sh +# id +uid=0(root) gid=0(root) groups=0(root) +# ls -l /tmp/test +-rw-rw----. 1 nobody nobody 8 Nov 30 12:40 /tmp/test +# cat /tmp/test +cat: /tmp/test: Permission denied +``` + +The **\--uidmap** setting above tells Podman to map a range of 5000 UIDs inside the container, starting with UID 100000 outside the container (so the range is 100000-104999) to a range starting at UID 0 inside the container (so the range is 0-4999). Inside the container, if my process is running as UID 1, it is 100001 on the host + +Since the real UID=0 is not mapped into the container, any file owned by root will be treated as owned by nobody. Even if the process inside the container has **CAP_DAC_OVERRIDE** , it can't override this protection. **DAC_OVERRIDE** enables root processes to read/write any file on the system, even if the process was not owned by root or world readable or writable. + +User namespace capabilities are not the same as capabilities on the host. They are namespaced capabilities. This means my container root has capabilities only within the container—really only across the range of UIDs that were mapped into the user namespace. If a container process escaped the container, it wouldn't have any capabilities over UIDs not mapped into the user namespace, including UID=0. Even if the processes could somehow enter another container, they would not have those capabilities if the container uses a different range of UIDs. + +Note that SELinux and other technologies also limit what would happen if a container process broke out of the container. + +### Using `podman top` to show user namespaces + +We have added features to **podman top** to allow you to examine the usernames of processes running inside a container and identify their real UIDs on the host. + +Let's start by running a sleep container using our UID mapping. + +``` +$ sudo podman run --uidmap 0:100000:5000 -d fedora sleep 1000 +``` + +Now run **podman top** : + +``` +$ sudo podman top --latest user huser +USER HUSER +root 100000 + +$ ps -ef | grep sleep +100000 21821 21809 0 08:04 ? 00:00:00 /usr/bin/coreutils --coreutils-prog-shebang=sleep /usr/bin/sleep 1000 +``` + +Notice **podman top** reports that the user process is running as root inside the container but as UID 100000 on the host (HUSER). Also the **ps** command confirms that the sleep process is running as UID 100000. + +Now let's run a second container, but this time we will choose a separate UID map starting at 200000. + +``` +$ sudo podman run --uidmap 0:200000:5000 -d fedora sleep 1000 +$ sudo podman top --latest user huser +USER HUSER +root 200000 + +$ ps -ef | grep sleep +100000 21821 21809 0 08:04 ? 00:00:00 /usr/bin/coreutils --coreutils-prog-shebang=sleep /usr/bin/sleep 1000 +200000 23644 23632 1 08:08 ? 00:00:00 /usr/bin/coreutils --coreutils-prog-shebang=sleep /usr/bin/sleep 1000 +``` + +Notice that **podman top** reports the second container is running as root inside the container but as UID=200000 on the host. + +Also look at the **ps** command—it shows both sleep processes running: one as 100000 and the other as 200000. + +This means running the containers inside separate user namespaces gives you traditional UID separation between processes, which has been the standard security tool of Linux/Unix from the beginning. + +### Problems with user namespaces + +For several years, I've advocated user namespace as the security tool everyone wants but hardly anyone has used. The reason is there hasn't been any filesystem support or a shifting file system. + +In containers, you want to share the **base** image between lots of containers. The examples above use the Fedora base image in each example. Most of the files in the Fedora image are owned by real UID=0. If I run a container on this image with the user namespace 0:100000:5000, by default it sees all of these files as owned by nobody, so we need to shift all of these UIDs to match the user namespace. For years, I've wanted a mount option to tell the kernel to remap these file UIDs to match the user namespace. Upstream kernel storage developers continue to investigate and make progress on this feature, but it is a difficult problem. + + +Podman can use different user namespaces on the same image because of automatic [chowning][6] built into [containers/storage][7] by a team led by Nalin Dahyabhai. Podman uses containers/storage, and the first time Podman uses a container image in a new user namespace, container/storage "chowns" (i.e., changes ownership for) all files in the image to the UIDs mapped in the user namespace and creates a new image. Think of this as the **fedora:0:100000:5000** image. + +When Podman runs another container on the image with the same UID mappings, it uses the "pre-chowned" image. When I run the second container on 0:200000:5000, containers/storage creates a second image, let's call it **fedora:0:200000:5000**. + +Note if you are doing a **podman build** or **podman commit** and push the newly created image to a container registry, Podman will use container/storage to reverse the shift and push the image with all files chowned back to real UID=0. + +This can cause a real slowdown in creating containers in new UID mappings since the **chown** can be slow depending on the number of files in the image. Also, on a normal [OverlayFS][8], every file in the image gets copied up. The normal Fedora image can take up to 30 seconds to finish the chown and start the container. + +Luckily, the Red Hat kernel storage team, primarily Vivek Goyal and Miklos Szeredi, added a new feature to OverlayFS in kernel 4.19. The feature is called **metadata only copy-up**. If you mount an overlay filesystem with **metacopy=on** as a mount option, it will not copy up the contents of the lower layers when you change file attributes; the kernel creates new inodes that include the attributes with references pointing at the lower-level data. It will still copy up the contents if the content changes. This functionality is available in the Red Hat Enterprise Linux 8 Beta, if you want to try it out. + +This means container chowning can happen in a couple of seconds, and you won't double the storage space for each container. + +This makes running containers with tools like Podman in separate user namespaces viable, greatly increasing the security of the system. + +### Going forward + +I want to add a new flag, like **\--userns=auto** , to Podman that will tell it to automatically pick a unique user namespace for each container you run. This is similar to the way SELinux works with separate multi-category security (MCS) labels. If you set the environment variable **PODMAN_USERNS=auto** , you won't even need to set the flag. + +Podman is finally allowing users to run containers in separate user namespaces. Tools like [Buildah][9] and [CRI-O][10] will also be able to take advantage of user namespaces. For CRI-O, however, Kubernetes needs to understand which user namespace will run the container engine, and the upstream is working on that. + +In my next article, I will explain how to run Podman as non-root in a user namespace. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/12/podman-and-user-namespaces + +作者：[Daniel J Walsh][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/rhatdan +[b]: https://github.com/lujun9972 +[1]: https://podman.io/ +[2]: https://github.com/containers/libpod +[3]: https://opensource.com/article/18/10/podman-more-secure-way-run-containers +[4]: http://man7.org/linux/man-pages/man7/user_namespaces.7.html +[5]: https://chmodcommand.com/chmod-660/ +[6]: https://en.wikipedia.org/wiki/Chown +[7]: https://github.com/containers/storage +[8]: https://en.wikipedia.org/wiki/OverlayFS +[9]: https://buildah.io/ +[10]: http://cri-o.io/ diff --git a/sources/tech/20181214 Tips for using Flood Element for performance testing.md b/sources/tech/20181214 Tips for using Flood Element for performance testing.md new file mode 100644 index 0000000000..90994b0724 --- /dev/null +++ b/sources/tech/20181214 Tips for using Flood Element for performance testing.md @@ -0,0 +1,180 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Tips for using Flood Element for performance testing) +[#]: via: (https://opensource.com/article/18/12/tips-flood-element-testing) +[#]: author: (Nicole van der Hoeven https://opensource.com/users/nicolevanderhoeven) + +Tips for using Flood Element for performance testing +====== +Get started with this powerful, intuitive load testing tool. + + +In case you missed it, there’s a new performance test tool on the block: [Flood Element][1]. It’s a scalable, browser-based tool that allows you to write scripts in JavaScript that interact with web pages like a real user would. + +Browser Level Users is a [newer approach to load testing][2] that overcomes many of the common challenges we hear about traditional methods of testing. It offers: + + * Scripting that is akin to common functional tools like Selenium and easier to learn + * More realistic results that are based on true browser performance rather than API response + * The ability to test against all components of your web app, including things like JavaScript that are rendered via the browser + + + +Given the above benefits, it’s a no-brainer to check out Flood Element for your web load testing, especially if you have struggled with existing tools like JMeter or HP LoadRunner. + +Pairing Element with [Flood][3] turns it into a pretty powerful load test tool. We have a [great guide here][4] that you can follow if you’d like to get started. I’ve been using and testing Element for several months now, and I’d like to share some tips I’ve learned along the way. + +### Initializing your script + +You can always start from scratch, but the quickest way to get started is to type `element init myfirstelementtest` from your terminal, filling in your preferred project name. + +You’ll then be asked to type the title of your test as well as the URL you’d like to script against. After a minute, you’ll see that a new directory has been created: + + + +Element will automatically create a file called **test.ts**. This file contains the skeleton of a script, along with some sample code to help you find a button and then click on it. But before you open it, let’s move on to… + +### Choosing the right text editor + +Scripting in Element is already pretty simple, but two things that help are syntax highlighting and code completion. Syntax highlighting will greatly improve the experience of learning a new test tool like Element, and code completion will make your scripting lightning-fast as you become more experienced. My text editor of choice is [Visual Studio Code][5], which has both of those features. It’s slick and clean, and it does the job. + +Syntax highlighting is when the text editor intelligently changes the font color of your code according to its role in the programming language you’re using. Here’s a screenshot of the **test.ts** file we generated earlier in VS Code to show you what I mean: + + + +This makes it easier to make sense of the code at a glance: Comments are in green, values and labels are in orange, etc. + +Code completion is when you start to type something, and VS Code helpfully opens a context menu with suggestions for methods you can use. + +![][6] + +I love this because it means I don’t need to remember the exact name of the method. It also suggests names of variables you’ve already defined and highlights code that doesn’t make sense. This will help to make your tests more maintainable and readable for others, which is a great benefit as you look to scale your testing out in the future. + + + +### Taking screenshots + +One of the most powerful features of Element is its ability to take screenshots. I find it immensely useful when debugging because sometimes it’s just easier to see what’s going on visually. With protocol-based tools, debugging can be a much more involved and technical process. + +There are two ways to take screenshots in Element: + + 1. Add a setting to automatically take a screenshot when an error is encountered. You can do this by setting `screenshotOnFailure` to "true" in `TestSettings`: + + + +``` +export const settings: TestSettings = { + device: Device.iPadLandscape, + userAgent: 'flood-chrome-test', + clearCache: true, + disableCache: true, + screenshotOnFailure: true, +} +``` + + 2. Explicitly take a screenshot at a particular point in the script. You can do this by adding + + + +``` +await browser.takeScreenshot() +``` + +to your code. + +### Viewing screenshots + +Once you’ve taken screenshots within your tests, you will probably want to view them and know that they will be stored for future safekeeping. Whether you are running your test locally on have uploaded it to Flood to run with increased concurrency, Flood Element has you covered. + +**Locally run tests** + +Screenshots will be saved as .jpg files in a timestamped folder corresponding to your run. It should look something like this: **…myfirstelementtest/tmp/element-results/test/2018-11-20T135700.595Z/flood/screenshots/**. The screenshots will be uniquely named so that new screenshots, even for the same step, don’t overwrite older ones. + +However, I rarely need to look up the screenshots in that folder because I prefer to see them in iTerm2 for MacOS. iTerm is an alternative to the terminal that works particularly well with Element. When you take a screenshot, iTerm actually shows it in-line: + + + +**Tests run in Flood** + +Running an Element script on Flood is ideal when you need larger concurrency. Rather than accessing your screenshot locally, Flood will centralize the images into your account, so the images remain even after the cloud load injectors are destroyed. You can get to the screenshot files by downloading Archived Results: + + + +You can also click on a step on the dashboard to see a filmstrip of your test: + + + +### Using logs + +You may need to check out the logs for more technical debugging, especially when the screenshots don’t tell the whole story. Again, whether you are running your test locally or have uploaded it to Flood to run with increased concurrency, Flood Element has you covered. + +**Locally run tests** + +You can print to the console by typing, for example: `console.log('orderValues = ’ + orderValues)` + +This will print the value of the variable `orderValues` at that point in the script. You would see this in your terminal if you’re running Element locally. + +**Tests run in Flood** + +If you’re running the script on Flood, you can either download the log (in the same Archived Results zipped file mentioned earlier) or click on the Logs tab: + + + +### Fun with flags + +Element comes with a few flags that give you more control over how the script is run locally. Here are a few of my favorites: + +**Headless flag** + +When in doubt, run Element in non-headless mode to see the script actually opening the web app on Chrome and interacting with the page. This is only possible locally, but there’s nothing like actually seeing for yourself what’s happening in real time instead of relying on screenshots and logs after the fact. To enable this mode, add the flag when running your test: + +``` +element run myfirstelementtest.ts --no-headless +``` + +**Watch flag** + +Element will automatically close the browser window when it encounters an error or finishes the iteration. Adding `--watch` will leave the browser window open and then monitor the script. As soon as the script is saved, it will automatically run it in the same window from the beginning. Simply add this flag like the above example: + +``` +--watch +``` + +**Dev tools flag** + +This opens a browser instance and runs the script with the Chrome Dev Tools open, allowing you to find locators for the next action you want to script. Simply add this flag as in the first example: + +``` +--dev-tools +``` + +For more flags, use `element run --help`. + +### Try Element + +You’ve just gotten a crash course on Flood Element and are ready to get started. [Download Element][1] to start writing functional test scripts and reusing them as load test scripts on Flood. If you don’t have a Flood account, you can easily sign up for a free trial [on the Flood website][7]. + +We’re proud to contribute to the open source community and can’t wait to have you try this new addition to the Flood line. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/12/tips-flood-element-testing + +作者：[Nicole van der Hoeven][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/nicolevanderhoeven +[b]: https://github.com/lujun9972 +[1]: https://element.flood.io/ +[2]: https://flood.io/blog/why-you-should-load-test-with-browsers/ +[3]: https://flood.io/ +[4]: https://help.flood.io/getting-started-with-load-testing/step-by-step-guide-flood-element +[5]: https://code.visualstudio.com/ +[6]: https://flood.io/wp-content/uploads/2018/11/vscode-codecompletion2.gif +[7]: https://flood.io/load-performance-testing-tool/free-load-testing-trial/ diff --git a/sources/tech/20181216 Schedule a visit with the Emacs psychiatrist.md b/sources/tech/20181216 Schedule a visit with the Emacs psychiatrist.md new file mode 100644 index 0000000000..6d72cda348 --- /dev/null +++ b/sources/tech/20181216 Schedule a visit with the Emacs psychiatrist.md @@ -0,0 +1,62 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Schedule a visit with the Emacs psychiatrist) +[#]: via: (https://opensource.com/article/18/12/linux-toy-eliza) +[#]: author: (Jason Baker https://opensource.com/users/jason-baker) + +Schedule a visit with the Emacs psychiatrist +====== +Eliza is a natural language processing chatbot hidden inside of one of Linux's most popular text editors. + + +Welcome to another day of the 24-day-long Linux command-line toys advent calendar. If this is your first visit to the series, you might be asking yourself what a command-line toy even is. We’re figuring that out as we go, but generally, it could be a game, or any simple diversion that helps you have fun at the terminal. + +Some of you will have seen various selections from our calendar before, but we hope there’s at least one new thing for everyone. + +Today's selection is a hidden gem inside of Emacs: Eliza, the Rogerian psychotherapist, a terminal toy ready to listen to everything you have to say. + +A brief aside: While this toy is amusing, your health is no laughing matter. Please take care of yourself this holiday season, physically and mentally, and if stress and anxiety from the holidays are having a negative impact on your wellbeing, please consider seeing a professional for guidance. It really can help. + +To launch [Eliza][1], first, you'll need to launch Emacs. There's a good chance Emacs is already installed on your system, but if it's not, it's almost certainly in your default repositories. + +Since I've been pretty fastidious about keeping this series in the terminal, launch Emacs with the **-nw** flag to keep in within your terminal emulator. + +``` +$ emacs -nw +``` + +Inside of Emacs, type M-x doctor to launch Eliza. For those of you like me from a Vim background who have no idea what this means, just hit escape, type x and then type doctor. Then, share all of your holiday frustrations. + +Eliza goes way back, all the way to the mid-1960s a the MIT Artificial Intelligence Lab. [Wikipedia][2] has a rather fascinating look at her history. + +Eliza isn't the only amusement inside of Emacs. Check out the [manual][3] for a whole list of fun toys. + + +![Linux toy: eliza animated][5] + +Do you have a favorite command-line toy that you think I ought to profile? We're running out of time, but I'd still love to hear your suggestions. Let me know in the comments below, and I'll check it out. And let me know what you thought of today's amusement. + +Be sure to check out yesterday's toy, [Head to the arcade in your Linux terminal with this Pac-man clone][6], and come back tomorrow for another! + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/12/linux-toy-eliza + +作者：[Jason Baker][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/jason-baker +[b]: https://github.com/lujun9972 +[1]: https://www.emacswiki.org/emacs/EmacsDoctor +[2]: https://en.wikipedia.org/wiki/ELIZA +[3]: https://www.gnu.org/software/emacs/manual/html_node/emacs/Amusements.html +[4]: /file/417326 +[5]: https://opensource.com/sites/default/files/uploads/linux-toy-eliza-animated.gif (Linux toy: eliza animated) +[6]: https://opensource.com/article/18/12/linux-toy-myman diff --git a/sources/tech/20181217 6 tips and tricks for using KeePassX to secure your passwords.md b/sources/tech/20181217 6 tips and tricks for using KeePassX to secure your passwords.md new file mode 100644 index 0000000000..ad688a7820 --- /dev/null +++ b/sources/tech/20181217 6 tips and tricks for using KeePassX to secure your passwords.md @@ -0,0 +1,78 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (6 tips and tricks for using KeePassX to secure your passwords) +[#]: via: (https://opensource.com/article/18/12/keepassx-security-best-practices) +[#]: author: (Michael McCune https://opensource.com/users/elmiko) + +6 tips and tricks for using KeePassX to secure your passwords +====== +Get more out of your password manager by following these best practices. + + +Our increasingly interconnected digital world makes security an essential and common discussion topic. We hear about [data breaches][1] with alarming regularity and are often on our own to make informed decisions about how to use technology securely. Although security is a deep and nuanced topic, there are some easy daily habits you can keep to reduce your attack surface. + +Securing passwords and account information is something that affects anyone today. Technologies like [OAuth][2] help make our lives simpler by reducing the number of accounts we need to create, but we are still left with a staggering number of places where we need new, unique information to keep our records secure. An easy way to deal with the increased mental load of organizing all this sensitive information is to use a password manager like [KeePassX][3]. + +In this article, I will explain the importance of keeping your password information secure and offer suggestions for getting the most out of KeePassX. For an introduction to KeePassX and its features, I highly recommend Ricardo Frydman's article "[Managing passwords in Linux with KeePassX][4]." + +### Why are unique passwords important? + +Using a different password for each account is the first step in ensuring that your accounts are not vulnerable to shared information leaks. Generating new credentials for every account is time-consuming, and it is extremely common for people to fall into the trap of using the same password on several accounts. The main problem with reusing passwords is that you increase the number of accounts an attacker could access if one of them experiences a credential breach. + +It may seem like a burden to create new credentials for each account, but the few minutes you spend creating and recording this information will pay for itself many times over in the event of a data breach. This is where password management tools like KeePassX are invaluable for providing convenience and reliability in securing your logins. + +### 3 tips for getting the most out of KeePassX + +I have been using KeePassX to manage my password information for many years, and it has become a primary resource in my digital toolbox. Overall, it's fairly simple to use, but there are a few best practices I've learned that I think are worth highlighting. + + 1. Add the direct login URL for each account entry. KeePassX has a very convenient shortcut to open the URL listed with an entry. (It's Control+Shift+U on Linux.) When creating a new account entry for a website, I spend some time to locate the site's direct login URL. Although most websites have a login widget in their navigation toolbars, they also usually have direct pages for login forms. By putting this URL into the URL field on the account entry setup form, I can use the shortcut to directly open the login page in my browser. + + + + 2. Use the Notes field to record extra security information. In addition to passwords, most websites will ask several questions to create additional authentication factors for an account. I use the Notes sections in my account entries to record these additional factors. + + + + 3. Turn on automatic database locking. In the **Application Settings** under the **Tools** menu, there is an option to lock the database after a period of inactivity. Enabling this option is a good common-sense measure, similar to enabling a password-protected screen lock, that will help ensure your password database is not left open and unprotected if someone else gains access to your computer. + + + +### Food for thought + +Protecting your accounts with better password practices and daily habits is just the beginning. Once you start using a password manager, you need to consider issues like protecting the password database file and ensuring you don't forget or lose the master credentials. + +The cloud-native world of disconnected devices and edge computing makes having a central password store essential. The practices and methodologies you adopt will help minimize your risk while you explore and work in the digital world. + + 1. Be aware of retention policies when storing your database in the cloud. KeePassX's database has an open format used by several tools on multiple platforms. Sooner or later, you will want to transfer your database to another device. As you do this, consider the medium you will use to transfer the file. The best option is to use some sort of direct transfer between devices, but this is not always convenient. Always think about where the database file might be stored as it winds its way through the information superhighway; an email may get cached on a server, an object store may move old files to a trash folder. Learn about these interactions for the platforms you are using before deciding where and how you will share your database file. + + 2. Consider the source of truth for your database while you're making edits. After you share your database file between devices, you might need to create accounts for new services or change information for existing services while using a device. To ensure your information is always correct across all your devices, you need to make sure any edits you make on one device end up in all copies of the database file. There is no easy solution to this problem, but you might think about making all edits from a single device or storing the master copy in a location where all your devices can make edits. + + 3. Do you really need to know your passwords? This is more of a philosophical question that touches on the nature of memorable passwords, convenience, and secrecy. I hardly look at passwords as I create them for new accounts; in most cases, I don't even click the "Show Password" checkbox. There is an idea that you can be more secure by not knowing your passwords, as it would be impossible to compel you to provide them. This may seem like a worrisome idea at first, but consider that you can recover or reset passwords for most accounts through alternate verification methods. When you consider that you might want to change your passwords on a semi-regular basis, it almost makes more sense to treat them as ephemeral information that can be regenerated or replaced. + + + + +Here are a few more ideas to consider as you develop your best practices. + +I hope these tips and tricks have helped expand your knowledge of password management and KeePassX. You can find tools that support the KeePass database format on nearly every platform. If you are not currently using a password manager or have never tried KeePassX, I highly recommend doing so now! + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/12/keepassx-security-best-practices + +作者：[Michael McCune][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/elmiko +[b]: https://github.com/lujun9972 +[1]: https://vigilante.pw/ +[2]: https://en.wikipedia.org/wiki/OAuth +[3]: https://www.keepassx.org/ +[4]: https://opensource.com/business/16/5/keepassx diff --git a/sources/tech/20181218 Insync- The Hassleless Way of Using Google Drive on Linux.md b/sources/tech/20181218 Insync- The Hassleless Way of Using Google Drive on Linux.md new file mode 100644 index 0000000000..c10e7ae4ed --- /dev/null +++ b/sources/tech/20181218 Insync- The Hassleless Way of Using Google Drive on Linux.md @@ -0,0 +1,137 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Insync: The Hassleless Way of Using Google Drive on Linux) +[#]: via: (https://itsfoss.com/insync-linux-review/) +[#]: author: (Abhishek Prakash https://itsfoss.com/author/abhishek/) + +Insync: The Hassleless Way of Using Google Drive on Linux +====== + +Using Google Drive on Linux is a pain and you probably already know that. There is no official desktop client of Google Drive for Linux. It’s been [more than six years since Google promised Google Drive on Linux][1] but it doesn’t seem to be happening. + +In the absence of the official Google Drive client on Linux, you have no option other than trying the alternatives. I have already discussed a number of [tools that allow you to use Google Drive on Linux][2]. One of those to[ols is][3] Insync, and in my opinion, this is your best bet for a native Google Drive experience on desktop Linux. + +Note that Insync is not an open source software. Heck, it is not even free to use. + +But it has so many features that it becomes an essential tool for those Linux users who rely heavily on Google Drive. + +I briefly discussed Insync in the old article about [Google Drive and Linux][2]. In this article, I’ll discuss Insync features in detail. + +### Insync brings native Google Drive experience to Linux desktop + +![Use insync to access Google Drive in Linux][4] + +The core competency of Insync is syncing your Google Drive, but the app is much more than that. It has features to help you maximize and control your productivity, your Google Drive and your files such as: + + * Cross-platform access (supports Linux, Windows and macOS) + * Easy multiple Google Drive accounts access + * Choose your syncing location. Sync files to your hard drive, external drives and NAS! + * Support for features like file matching, symlink and ignore list + + + +Let me show you some of the main features in action: + +#### Cross-platform in true sense + +Insync claims to run the same app across all operating systems i.e., Linux, Windows, and macOS. That means that you can access the same UI across different OSes, making it easy for you to manage your files across multiple machines. + +![The UI of Insync and the default location of the Insync folder.][5]The UI of Insync and the default location of the Insync folder. + +#### Multiple Google account management + +Insync interface allows you to manage multiple Google Drive accounts seamlessly. You can easily switch between several accounts just by clicking your Google account. + +![Switching between multiple Google accounts in Insync][6]Switching between multiple Google accounts + +#### Custom sync folders + +Customize the way you sync your files and folders. You can easily set your syncing destination anywhere on your machine including external drive and network drives. + +![Customize sync location in Insync][7]Customize sync location + +The selective syncing mode also allows you to easily select a number of files and folders you’d want to sync (or unsync) in your local machine. This includes selectively syncing files within folders. + +![Selective synchronization in Insync][8]Selective synchronization + +It has features like file matching and ‘ignore list’ to help you filter files you don’t want to sync or files that you already have on your machine. + +![File matching feature in Insync][9]Avoids duplication of files + +The ‘ignore list’ allows you to set rules to exclude certain type of files from synchronization. + +![Selective syncing based on rules in Insync][10]Selective syncing based on rules + +If you prefer to work out of the desktop, you have an “Add to Insync” feature that will allow you to add any local file to your Drive. + +![Sync files right from your desktop][11]Sync files right from your desktop + +Insync also supports symlinks for those with workflows that use symbolic links. To learn more about Insync and symlinks, you can refer to [this article.][12] + +#### Exclusive features for Linux + +Insync supports the most commonly used 64-bit Linux distributions like **Ubuntu, Debian and Fedora**. You can check out the full list of distribution support [here][13]. + +Insync also has [headless][14] support for those looking to sync through the command line interface. This is perfect if you use a distro that is not fully supported by the GUI app or if you are working with servers or if you simply prefer the CLI. + +![Insync CLI][15]Command Line Interface + +You can learn more about installing and running Insync headless [here][16]. + +### Insync pricing and special discount + +Insync is a premium tool and it comes with a [price tag][17]. You have 2 licenses to choose from: + + * **Prime** is priced at $29.99 per Google account. You’ll get access to: cross-platform syncing, multiple accounts access and **support**. + * **Teams** is priced at $49.99 per Google account. You’ll be able to access all the Prime features + Team Drives syncing + + + +It’s a one-time fee which means once you buy it, you don’t have to pay it again. In a world where everything is paid monthly, it’s refreshing to pay for software that is still one-time! + +Each Google account has a 15-day free trial that will allow you to test the full suite of features, including [Team Drives][18] syncing. + +If you think it’s a bit expensive for your budget, I have good news for you. As an It’s FOSS reader, you get Insync at 25% discount. + +Just use the code ITSFOSS25 at checkout time and you will get 25% immediate discount on any license. Isn’t it cool? + +If you are not certain yet, you can try Insync free for 15 days. And if you think it’s worth the money, purchase the license with **ITSFOSS25** coupon code. + +You can download Insync from their website. + +I have used Insync from the time when it was available for free and I have always liked it. They have added more features over the time and improved its UI and performance. Overall, it’s a nice-to-have application if you use Google Drive a lot and do not mind paying for the efforts of the developers. + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/insync-linux-review/ + +作者：[Abhishek Prakash][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://itsfoss.com/author/abhishek/ +[b]: https://github.com/lujun9972 +[1]: https://abevoelker.github.io/how-long-since-google-said-a-google-drive-linux-client-is-coming/ +[2]: https://itsfoss.com/use-google-drive-linux/ +[3]: https://www.insynchq.com +[4]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2018/12/google-drive-linux-insync.jpeg?resize=800%2C450&ssl=1 +[5]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2018/11/insync_interface.jpeg?fit=800%2C501&ssl=1 +[6]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2018/11/insync_multiple_google_account.jpeg?ssl=1 +[7]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2018/11/insync_folder_settings.png?ssl=1 +[8]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2018/11/insync_selective_sync.png?ssl=1 +[9]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2018/11/insync_file_matching.jpeg?ssl=1 +[10]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2018/11/insync_ignore_list_1.png?ssl=1 +[11]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2018/11/add-to-insync-shortcut.jpeg?ssl=1 +[12]: https://help.insynchq.com/key-features-and-syncing-explained/syncing-superpowers/using-symlinks-on-google-drive-with-insync +[13]: https://www.insynchq.com/downloads +[14]: https://en.wikipedia.org/wiki/Headless_software +[15]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/11/insync_cli.jpeg?fit=800%2C478&ssl=1 +[16]: https://help.insynchq.com/installation-on-windows-linux-and-macos/advanced/linux-controlling-insync-via-command-line-cli +[17]: https://www.insynchq.com/pricing +[18]: https://gsuite.google.com/learning-center/products/drive/get-started-team-drive/#!/ diff --git a/sources/tech/20181219 PowerTOP - Monitors Power Usage and Improve Laptop Battery Life in Linux.md b/sources/tech/20181219 PowerTOP - Monitors Power Usage and Improve Laptop Battery Life in Linux.md new file mode 100644 index 0000000000..a615ffc73a --- /dev/null +++ b/sources/tech/20181219 PowerTOP - Monitors Power Usage and Improve Laptop Battery Life in Linux.md @@ -0,0 +1,411 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (PowerTOP – Monitors Power Usage and Improve Laptop Battery Life in Linux) +[#]: via: (https://www.2daygeek.com/powertop-monitors-laptop-battery-usage-linux/) +[#]: author: (Vinoth Kumar https://www.2daygeek.com/author/vinoth/) + +PowerTOP – Monitors Power Usage and Improve Laptop Battery Life in Linux +====== + +We all know, we almost 80-90% migrated from PC (Desktop) to laptop. + +But one thing we want from a laptop, it’s long battery life and we want to use every drop of power. + +So it’s good to know where our power is going and getting waste. + +You can use the powertop utility to see what’s drawing power when your system’s not plugged in. + +You need to run the powertop utility in terminal with super user privilege. + +It will access the hardware and measure power usage. + +### What is PowerTOP + +PowerTOP is a Linux tool to diagnose issues with power consumption and power management. + +It was developed by Intel to enable various power-saving modes in kernel, userspace, and hardware. + +In addition to being a diagnostic tool, PowerTOP also has an interactive mode where the user can experiment various power management settings for cases where the Linux distribution has not enabled these settings. + +It is possible to monitor processes and show which of them are utilizing the CPU and wake it from its Idle-States, allowing to identify applications with particular high power demands. + +### How to Install PowerTOP + +PowerTOP package is available in most of the distributions official repository so, use the distributions **[Package Manager][1]** to install it. + +For **`Fedora`** system, use **[DNF Command][2]** to install PowerTOP. + +``` +$ sudo dnf install powertop +``` + +For **`Debian/Ubuntu`** systems, use **[APT-GET Command][3]** or **[APT Command][4]** to install PowerTOP. + +``` +$ sudo apt install powertop +``` + +For **`Arch Linux`** based systems, use **[Pacman Command][5]** to install PowerTOP. + +``` +$ sudo pacman -S powertop +``` + +For **`RHEL/CentOS`** systems, use **[YUM Command][6]** to install PowerTOP. + +``` +$ sudo yum install powertop +``` + +For **`openSUSE Leap`** system, use **[Zypper Command][7]** to install PowerTOP. + +``` +$ sudo zypper install powertop +``` + +### How To Access PowerTOP + +PowerTOP requires super user privilege so, run as root to use PowerTOP utility on your Linux system. + +By default it shows `Overview` tab where we can see the power usage consumption for all the devices. Also shows your system wakeups seconds. + +``` +$ sudo powertop + +PowerTOP v2.9 Overview Idle stats Frequency stats Device stats Tunables + +The battery reports a discharge rate of 12.6 W +The power consumed was 259 J +The estimated remaining time is 1 hours, 52 minutes + +Summary: 1692.9 wakeups/second, 0.0 GPU ops/seconds, 0.0 VFS ops/sec and 54.9% CPU use + + Usage Events/s Category Description + 9.3 ms/s 529.4 Timer tick_sched_timer + 378.5 ms/s 139.8 Process [PID 2991] /usr/lib/firefox/firefox -contentproc -childID 7 -isForBrowser -prefsLen 8314 -prefMapSize 173895 -schedulerPrefs 00 + 7.5 ms/s 141.7 Timer hrtimer_wakeup + 3.3 ms/s 102.7 Process [PID 1527] /usr/lib/firefox/firefox --new-window + 11.6 ms/s 69.1 Process [PID 1568] /usr/lib/firefox/firefox -contentproc -childID 1 -isForBrowser -prefsLen 1 -prefMapSize 173895 -schedulerPrefs 0001, + 6.2 ms/s 59.0 Process [PID 1496] /usr/lib/firefox/firefox --new-window + 2.1 ms/s 59.6 Process [PID 2466] /usr/lib/firefox/firefox -contentproc -childID 3 -isForBrowser -prefsLen 5814 -prefMapSize 173895 -schedulerPrefs 00 + 1.8 ms/s 52.3 Process [PID 2052] /usr/lib/firefox/firefox -contentproc -childID 4 -isForBrowser -prefsLen 5814 -prefMapSize 173895 -schedulerPrefs 00 + 1.8 ms/s 50.8 Process [PID 3034] /usr/lib/firefox/firefox -contentproc -childID 7 -isForBrowser -prefsLen 8314 -prefMapSize 173895 -schedulerPrefs 00 + 3.6 ms/s 48.4 Process [PID 3009] /usr/lib/firefox/firefox -contentproc -childID 7 -isForBrowser -prefsLen 8314 -prefMapSize 173895 -schedulerPrefs 00 + 7.5 ms/s 46.2 Process [PID 2996] /usr/lib/firefox/firefox -contentproc -childID 7 -isForBrowser -prefsLen 8314 -prefMapSize 173895 -schedulerPrefs 00 + 25.2 ms/s 33.6 Process [PID 1528] /usr/lib/firefox/firefox --new-window + 5.7 ms/s 32.2 Interrupt [7] sched(softirq) + 2.1 ms/s 32.2 Process [PID 1811] /usr/lib/firefox/firefox -contentproc -childID 4 -isForBrowser -prefsLen 5814 -prefMapSize 173895 -schedulerPrefs 00 + 19.7 ms/s 25.0 Process [PID 1794] /usr/lib/firefox/firefox -contentproc -childID 4 -isForBrowser -prefsLen 5814 -prefMapSize 173895 -schedulerPrefs 00 + 1.9 ms/s 31.5 Process [PID 1596] /usr/lib/firefox/firefox -contentproc -childID 1 -isForBrowser -prefsLen 1 -prefMapSize 173895 -schedulerPrefs 0001, + 3.1 ms/s 29.9 Process [PID 1535] /usr/lib/firefox/firefox --new-window + 7.1 ms/s 28.2 Process [PID 1488] /usr/lib/firefox/firefox --new-window + 1.8 ms/s 29.5 Process [PID 1762] /usr/lib/firefox/firefox -contentproc -childID 3 -isForBrowser -prefsLen 5814 -prefMapSize 173895 -schedulerPrefs 00 + 8.8 ms/s 23.3 Process [PID 1121] /usr/bin/gnome-shell + 1.2 ms/s 21.8 Process [PID 1657] /usr/lib/firefox/firefox -contentproc -childID 2 -isForBrowser -prefsLen 920 -prefMapSize 173895 -schedulerPrefs 000 + 13.3 ms/s 13.9 Process [PID 1746] /usr/lib/firefox/firefox -contentproc -childID 3 -isForBrowser -prefsLen 5814 -prefMapSize 173895 -schedulerPrefs 00 + 2.7 ms/s 11.1 Process [PID 3410] /usr/lib/gnome-terminal-server + 3.8 ms/s 10.8 Process [PID 1057] /usr/lib/Xorg vt2 -displayfd 3 -auth /run/user/1000/gdm/Xauthority -nolisten tcp -background none -noreset -keeptty + 3.1 ms/s 9.8 Process [PID 1629] /usr/lib/firefox/firefox -contentproc -childID 2 -isForBrowser -prefsLen 920 -prefMapSize 173895 -schedulerPrefs 000 + 0.9 ms/s 6.7 Interrupt [136] xhci_hcd + 278.0 us/s 6.4 Process [PID 414] [irq/141-iwlwifi] + 128.7 us/s 5.7 Process [PID 1] /sbin/init + 118.5 us/s 5.2 Process [PID 10] [rcu_preempt] + 49.0 us/s 4.7 Interrupt [0] HI_SOFTIRQ + 459.3 us/s 3.1 Interrupt [142] i915 + 2.1 ms/s 2.3 Process [PID 3451] powertop + 8.4 us/s 2.7 kWork intel_atomic_helper_free_state_ + 1.2 ms/s 1.8 kWork intel_atomic_commit_work + 374.2 us/s 2.1 Interrupt [9] acpi + 42.1 us/s 1.8 kWork intel_atomic_cleanup_work + 3.5 ms/s 0.25 kWork delayed_fput + 238.0 us/s 1.5 Process [PID 907] /usr/lib/upowerd + 17.7 us/s 1.5 Timer intel_uncore_fw_release_timer + 26.4 us/s 1.4 Process [PID 576] [i915/signal:0] + 19.8 us/s 1.3 Timer watchdog_timer_fn + 1.1 ms/s 0.00 Process [PID 206] [kworker/7:2] + 2.4 ms/s 0.00 Interrupt [1] timer(softirq) + 13.4 us/s 0.9 Process [PID 9] [ksoftirqd/0] + + Exit | / Navigate | +``` + +The powertop output looks similar to the above screenshot, it will be slightly different based on your hardware. This have many screen you can switch between screen the using `Tab` and `Shift+Tab` button. + +### Idle Stats Tab + +It displays various information about the processor. + +``` +PowerTOP v2.9 Overview Idle stats Frequency stats Device stats Tunables + + + Package | Core | CPU 0 CPU 4 + | | C0 active 6.7% 7.2% + | | POLL 0.0% 0.1 ms 0.0% 0.1 ms + | | C1E 1.2% 0.2 ms 1.6% 0.3 ms +C2 (pc2) 7.5% | | +C3 (pc3) 25.2% | C3 (cc3) 0.7% | C3 0.5% 0.2 ms 0.6% 0.1 ms +C6 (pc6) 0.0% | C6 (cc6) 7.1% | C6 6.6% 0.5 ms 6.3% 0.5 ms +C7 (pc7) 0.0% | C7 (cc7) 59.8% | C7s 0.0% 0.0 ms 0.0% 0.0 ms +C8 (pc8) 0.0% | | C8 33.9% 1.6 ms 32.3% 1.5 ms +C9 (pc9) 0.0% | | C9 2.1% 3.4 ms 0.7% 2.8 ms +C10 (pc10) 0.0% | | C10 39.5% 4.7 ms 41.4% 4.7 ms + + | Core | CPU 1 CPU 5 + | | C0 active 8.3% 7.2% + | | POLL 0.0% 0.0 ms 0.0% 0.1 ms + | | C1E 1.3% 0.2 ms 1.4% 0.3 ms + | | + | C3 (cc3) 0.5% | C3 0.5% 0.2 ms 0.4% 0.2 ms + | C6 (cc6) 6.0% | C6 5.3% 0.5 ms 4.7% 0.5 ms + | C7 (cc7) 59.3% | C7s 0.0% 0.8 ms 0.0% 1.0 ms + | | C8 27.2% 1.5 ms 23.8% 1.4 ms + | | C9 1.6% 3.0 ms 0.5% 3.0 ms + | | C10 44.5% 4.7 ms 52.2% 4.6 ms + + | Core | CPU 2 CPU 6 + | | C0 active 11.2% 8.4% + | | POLL 0.0% 0.0 ms 0.0% 0.0 ms + | | C1E 1.4% 0.4 ms 1.3% 0.3 ms + | | + | C3 (cc3) 0.3% | C3 0.2% 0.1 ms 0.4% 0.2 ms + | C6 (cc6) 4.0% | C6 3.7% 0.5 ms 4.3% 0.5 ms + | C7 (cc7) 54.2% | C7s 0.0% 0.0 ms 0.0% 1.0 ms + | | C8 20.0% 1.5 ms 20.7% 1.4 ms + | | C9 1.0% 3.4 ms 0.4% 3.8 ms + | | C10 48.8% 4.6 ms 52.3% 5.0 ms + + | Core | CPU 3 CPU 7 + | | C0 active 8.8% 8.1% + | | POLL 0.0% 0.1 ms 0.0% 0.0 ms + | | C1E 1.2% 0.2 ms 1.2% 0.2 ms + | | + | C3 (cc3) 0.6% | C3 0.6% 0.2 ms 0.4% 0.2 ms + | C6 (cc6) 7.0% | C6 7.5% 0.5 ms 4.4% 0.5 ms + | C7 (cc7) 56.8% | C7s 0.0% 0.0 ms 0.0% 0.9 ms + | | C8 29.4% 1.4 ms 23.8% 1.4 ms + | | C9 1.1% 2.7 ms 0.7% 3.9 ms + | | C10 41.0% 4.0 ms 50.0% 4.8 ms + + + Exit | / Navigate | +``` + +### Frequency Stats Tab + +It displays the frequency of CPU. + +``` +PowerTOP v2.9 Overview Idle stats Frequency stats Device stats Tunables + + + Package | Core | CPU 0 CPU 4 + | | Average 930 MHz 1101 MHz +Idle | Idle | Idle + + | Core | CPU 1 CPU 5 + | | Average 1063 MHz 979 MHz + | Idle | Idle + + | Core | CPU 2 CPU 6 + | | Average 976 MHz 942 MHz + | Idle | Idle + + | Core | CPU 3 CPU 7 + | | Average 924 MHz 957 MHz + | Idle | Idle + +``` + +### Device Stats Tab + +It displays power usage information against only devices. + +``` +PowerTOP v2.9 Overview Idle stats Frequency stats Device stats Tunables + + +The battery reports a discharge rate of 13.8 W +The power consumed was 280 J + + Usage Device name + 46.7% CPU misc + 46.7% DRAM + 46.7% CPU core + 19.0% Display backlight + 0.0% Audio codec hwC0D0: Realtek + 0.0% USB device: Lenovo EasyCamera (160709000341) + 100.0% PCI Device: Intel Corporation HD Graphics 530 + 100.0% Radio device: iwlwifi + 100.0% PCI Device: O2 Micro, Inc. SD/MMC Card Reader Controller + 100.0% PCI Device: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Host Bridge/DRAM Registers + 100.0% USB device: Lenovo Wireless Optical Mouse N100 + 100.0% PCI Device: Intel Corporation Wireless 8260 + 100.0% PCI Device: Intel Corporation HM170/QM170 Chipset SATA Controller [AHCI Mode] + 100.0% Radio device: btusb + 100.0% PCI Device: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #4 + 100.0% USB device: xHCI Host Controller + 100.0% PCI Device: Intel Corporation 100 Series/C230 Series Chipset Family USB 3.0 xHCI Controller + 100.0% PCI Device: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller + 100.0% PCI Device: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #3 + 100.0% PCI Device: Samsung Electronics Co Ltd NVMe SSD Controller SM951/PM951 + 100.0% PCI Device: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #2 + 100.0% PCI Device: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #9 + 100.0% PCI Device: Intel Corporation 100 Series/C230 Series Chipset Family SMBus + 26.1 pkts/s Network interface: wlp8s0 (iwlwifi) + 0.0% USB device: usb-device-8087-0a2b + 0.0% runtime-reg-dummy + 0.0% Audio codec hwC0D2: Intel + 0.0 pkts/s Network interface: enp9s0 (r8168) + 0.0% PCI Device: Intel Corporation 100 Series/C230 Series Chipset Family Power Management Controller + 0.0% PCI Device: Intel Corporation HM170 Chipset LPC/eSPI Controller + 0.0% PCI Device: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor PCIe Controller (x16) + 0.0% PCI Device: Intel Corporation 100 Series/C230 Series Chipset Family MEI Controller #1 + 0.0% PCI Device: NVIDIA Corporation GM107M [GeForce GTX 960M] + 0.0% I2C Adapter (i2c-8): nvkm-0000:01:00.0-bus-0005 + 0.0% runtime-PNP0C14:00 + 0.0% PCI Device: Intel Corporation 100 Series/C230 Series Chipset Family HD Audio Controller + 0.0% runtime-PNP0C0C:00 + 0.0% USB device: xHCI Host Controller + 0.0% runtime-ACPI000C:00 + 0.0% runtime-regulatory.0 + 0.0% runtime-PNP0C14:01 + 0.0% runtime-vesa-framebuffer.0 + 0.0% runtime-coretemp.0 + 0.0% runtime-alarmtimer + + Exit | / Navigate | +``` + +### Tunables Stats Tab + +This tab is important area that provides suggestions to optimize your laptop battery. + +``` +PowerTOP v2.9 Overview Idle stats Frequency stats Device stats Tunables + + +>> Bad Enable SATA link power management for host2 + Bad Enable SATA link power management for host3 + Bad Enable SATA link power management for host0 + Bad Enable SATA link power management for host1 + Bad VM writeback timeout + Bad Autosuspend for USB device Lenovo Wireless Optical Mouse N100 [1-2] + Good Bluetooth device interface status + Good Enable Audio codec power management + Good NMI watchdog should be turned off + Good Runtime PM for I2C Adapter i2c-7 (nvkm-0000:01:00.0-bus-0002) + Good Autosuspend for unknown USB device 1-11 (8087:0a2b) + Good Runtime PM for I2C Adapter i2c-3 (i915 gmbus dpd) + Good Autosuspend for USB device Lenovo EasyCamera [160709000341] + Good Runtime PM for I2C Adapter i2c-1 (i915 gmbus dpc) + Good Runtime PM for I2C Adapter i2c-12 (nvkm-0000:01:00.0-bus-0009) + Good Autosuspend for USB device xHCI Host Controller [usb1] + Good Runtime PM for I2C Adapter i2c-13 (nvkm-0000:01:00.0-aux-000a) + Good Runtime PM for I2C Adapter i2c-2 (i915 gmbus dpb) + Good Runtime PM for I2C Adapter i2c-8 (nvkm-0000:01:00.0-bus-0005) + Good Runtime PM for I2C Adapter i2c-15 (nvkm-0000:01:00.0-aux-000c) + Good Runtime PM for I2C Adapter i2c-16 (nvkm-0000:01:00.0-aux-000d) + Good Runtime PM for I2C Adapter i2c-5 (nvkm-0000:01:00.0-bus-0000) + Good Runtime PM for I2C Adapter i2c-0 (SMBus I801 adapter at 6040) + Good Runtime PM for I2C Adapter i2c-11 (nvkm-0000:01:00.0-bus-0008) + Good Runtime PM for I2C Adapter i2c-14 (nvkm-0000:01:00.0-aux-000b) + Good Autosuspend for USB device xHCI Host Controller [usb2] + Good Runtime PM for I2C Adapter i2c-9 (nvkm-0000:01:00.0-bus-0006) + Good Runtime PM for I2C Adapter i2c-10 (nvkm-0000:01:00.0-bus-0007) + Good Runtime PM for I2C Adapter i2c-6 (nvkm-0000:01:00.0-bus-0001) + Good Runtime PM for PCI Device Intel Corporation 100 Series/C230 Series Chipset Family HD Audio Controller + Good Runtime PM for PCI Device Intel Corporation 100 Series/C230 Series Chipset Family USB 3.0 xHCI Controller + Good Runtime PM for PCI Device Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Host Bridge/DRAM Registers + Good Runtime PM for PCI Device Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #9 + Good Runtime PM for PCI Device Intel Corporation HD Graphics 530 + Good Runtime PM for PCI Device Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller + Good Runtime PM for PCI Device Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #3 + Good Runtime PM for PCI Device O2 Micro, Inc. SD/MMC Card Reader Controller + Good Runtime PM for PCI Device Intel Corporation HM170 Chipset LPC/eSPI Controller + Good Runtime PM for PCI Device Intel Corporation 100 Series/C230 Series Chipset Family MEI Controller #1 + Good Runtime PM for PCI Device Samsung Electronics Co Ltd NVMe SSD Controller SM951/PM951 + Good Runtime PM for PCI Device Intel Corporation HM170/QM170 Chipset SATA Controller [AHCI Mode] + Good Runtime PM for PCI Device Intel Corporation 100 Series/C230 Series Chipset Family Power Management Controller + Good Runtime PM for PCI Device Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #2 + Good Runtime PM for PCI Device Intel Corporation Wireless 8260 + Good Runtime PM for PCI Device Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor PCIe Controller (x16) + Good Runtime PM for PCI Device Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #4 + Good Runtime PM for PCI Device Intel Corporation 100 Series/C230 Series Chipset Family SMBus + Good Runtime PM for PCI Device NVIDIA Corporation GM107M [GeForce GTX 960M] + + Exit | Toggle tunable | Window refresh +``` + +### How To Generate PowerTop HTML Report + +Run the following command to generate the PowerTop HTML report. + +``` +$ sudo powertop --html=powertop.html +modprobe cpufreq_stats failedLoaded 100 prior measurements +Cannot load from file /var/cache/powertop/saved_parameters.powertop +File will be loaded after taking minimum number of measurement(s) with battery only +RAPL device for cpu 0 +RAPL Using PowerCap Sysfs : Domain Mask f +RAPL device for cpu 0 +RAPL Using PowerCap Sysfs : Domain Mask f +Devfreq not enabled +glob returned GLOB_ABORTED +Cannot load from file /var/cache/powertop/saved_parameters.powertop +File will be loaded after taking minimum number of measurement(s) with battery only +Preparing to take measurements +To show power estimates do 182 measurement(s) connected to battery only +Taking 1 measurement(s) for a duration of 20 second(s) each. +PowerTOP outputing using base filename powertop.html +``` + +Navigate to `file:///home/daygeek/powertop.html` file to access the generated PowerTOP HTML report. +![][9] + +### Auto-Tune mode + +This feature sets all tunable options from `BAD` to `GOOD` which increase the laptop battery life in Linux. + +``` +$ sudo powertop --auto-tune +modprobe cpufreq_stats failedLoaded 210 prior measurements +Cannot load from file /var/cache/powertop/saved_parameters.powertop +File will be loaded after taking minimum number of measurement(s) with battery only +RAPL device for cpu 0 +RAPL Using PowerCap Sysfs : Domain Mask f +RAPL device for cpu 0 +RAPL Using PowerCap Sysfs : Domain Mask f +Devfreq not enabled +glob returned GLOB_ABORTED +Cannot load from file /var/cache/powertop/saved_parameters.powertop +File will be loaded after taking minimum number of measurement(s) with battery only +To show power estimates do 72 measurement(s) connected to battery only +Leaving PowerTOP +``` + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/powertop-monitors-laptop-battery-usage-linux/ + +作者：[Vinoth Kumar][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.2daygeek.com/author/vinoth/ +[b]: https://github.com/lujun9972 +[1]: https://www.2daygeek.com/category/package-management/ +[2]: https://www.2daygeek.com/dnf-command-examples-manage-packages-fedora-system/ +[3]: https://www.2daygeek.com/apt-get-apt-cache-command-examples-manage-packages-debian-ubuntu-systems/ +[4]: https://www.2daygeek.com/apt-command-examples-manage-packages-debian-ubuntu-systems/ +[5]: https://www.2daygeek.com/pacman-command-examples-manage-packages-arch-linux-system/ +[6]: https://www.2daygeek.com/yum-command-examples-manage-packages-rhel-centos-systems/ +[7]: https://www.2daygeek.com/zypper-command-examples-manage-packages-opensuse-system/ +[8]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[9]: https://www.2daygeek.com/wp-content/uploads/2015/07/powertop-html-output.jpg diff --git a/sources/tech/20181220 Getting started with Prometheus.md b/sources/tech/20181220 Getting started with Prometheus.md new file mode 100644 index 0000000000..79704addb7 --- /dev/null +++ b/sources/tech/20181220 Getting started with Prometheus.md @@ -0,0 +1,166 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Getting started with Prometheus) +[#]: via: (https://opensource.com/article/18/12/introduction-prometheus) +[#]: author: (Michael Zamot https://opensource.com/users/mzamot) + +Getting started with Prometheus +====== +Learn to install and write queries for the Prometheus monitoring and alerting system. + + +[Prometheus][1] is an open source monitoring and alerting system that directly scrapes metrics from agents running on the target hosts and stores the collected samples centrally on its server. Metrics can also be pushed using plugins like **collectd_exporter** —although this is not Promethius' default behavior, it may be useful in some environments where hosts are behind a firewall or prohibited from opening ports by security policy. + +Prometheus, a project of the [Cloud Native Computing Foundation][2], scales up using a federation model, which enables one Prometheus server to scrape another Prometheus server. This allows creation of a hierarchical topology, where a central system or higher-level Prometheus server can scrape aggregated data already collected from subordinate instances. + +Besides the Prometheus server, its most common components are its [Alertmanager][3] and its exporters. + +Alerting rules can be created within Prometheus and configured to send custom alerts to Alertmanager. Alertmanager then processes and handles these alerts, including sending notifications through different mechanisms like email or third-party services like [PagerDuty][4]. + +Prometheus' exporters can be libraries, processes, devices, or anything else that exposes the metrics that will be scraped by Prometheus. The metrics are available at the endpoint **/metrics** , which allows Prometheus to scrape them directly without needing an agent. The tutorial in this article uses **node_exporter** to expose the target hosts' hardware and operating system metrics. Exporters' outputs are plaintext and highly readable, which is one of Prometheus' strengths. + +In addition, you can configure [Grafana][5] to use Prometheus as a backend to provide data visualization and dashboarding functions. + +### Making sense of Prometheus' configuration file + +The number of seconds between when **/metrics** is scraped controls the granularity of the time-series database. This is defined in the configuration file as the **scrape_interval** parameter, which by default is set to 60 seconds. + +Targets are set for each scrape job in the **scrape_configs** section. Each job has its own name and a set of labels that can help filter, categorize, and make it easier to identify the target. One job can have many targets. + +### Installing Prometheus + +In this tutorial, for simplicity, we will install a Prometheus server and **node_exporter** with docker. Docker should already be installed and configured properly on your system. For a more in-depth, automated method, I recommend Steve Ovens' article [How to use Ansible to set up system monitoring with Prometheus][6]. + +Before starting, create the Prometheus configuration file **prometheus.yml** in your work directory as follows: + +``` +global: + scrape_interval: 15s + evaluation_interval: 15s + +scrape_configs: + - job_name: 'prometheus' + + static_configs: + - targets: ['localhost:9090'] + + - job_name: 'webservers' + + static_configs: + - targets: [' :9100'] +``` + +Start Prometheus with Docker by running the following command: + +``` +$ sudo docker run -d -p 9090:9090 -v +/path/to/prometheus.yml:/etc/prometheus/prometheus.yml +prom/prometheus +``` + +By default, the Prometheus server will use port 9090. If this port is already in use, you can change it by adding the parameter **\--web.listen-address=" : "** at the end of the previous command. + +In the machine you want to monitor, download and run the **node_exporter** container by using the following command: + +``` +$ sudo docker run -d -v "/proc:/host/proc" -v "/sys:/host/sys" -v +"/:/rootfs" --net="host" prom/node-exporter --path.procfs +/host/proc --path.sysfs /host/sys --collector.filesystem.ignored- +mount-points "^/(sys|proc|dev|host|etc)($|/)" +``` + +For the purposes of this learning exercise, you can install **node_exporter** and Prometheus on the same machine. Please note that it's not wise to run **node_exporter** under Docker in production—this is for testing purposes only. + +To verify that **node_exporter** is running, open your browser and navigate to **http:// :9100/metrics**. All the metrics collected will be displayed; these are the same metrics Prometheus will scrape. + + + +To verify the Prometheus server installation, open your browser and navigate to + 3361 0.00s 0.01s 0K 0K NE 0 0 E - 0% + 3363 0.01s 0.00s 0K 0K NE 0 0 E - 0% +31357 0.00s 0.00s 0K 0K -- - 1 S 1 0% bash + 3364 0.00s 0.00s 8032K 756K N- - 1 S 1 0% sleep + 2931 0.00s 0.00s 0K 0K -- - 1 I 1 0% kworker/u8:2-e + 3356 0.00s 0.00s 0K 0K -E 0 0 E - 0% + 3360 0.00s 0.00s 0K 0K NE 0 0 E - 0% + 3362 0.00s 0.00s 0K 0K NE 0 0 E - 0% +``` + +If you want to look at _just_ the disk stats, you can easily manage that with a command like this: + +``` +$ atop | grep DSK +$ atop | grep DSK +DSK | sda | busy 0% | read 122901 | write 3318e3 | avio 0.67 ms | +DSK | sdb | busy 0% | read 1168 | write 103 | avio 0.73 ms | +DSK | sda | busy 2% | read 0 | write 92 | avio 2.39 ms | +DSK | sda | busy 2% | read 0 | write 94 | avio 2.47 ms | +DSK | sda | busy 2% | read 0 | write 99 | avio 2.26 ms | +DSK | sda | busy 2% | read 0 | write 94 | avio 2.43 ms | +DSK | sda | busy 2% | read 0 | write 94 | avio 2.43 ms | +DSK | sda | busy 2% | read 0 | write 92 | avio 2.43 ms | +^C +``` + +### Being in the know with disk I/O + +Linux provides enough commands to give you good insights into how hard your disks are working and help you focus on potential problems or slowdowns. Hopefully, one of these commands will tell you just what you need to know when it's time to question disk performance. Occasional use of these commands will help ensure that especially busy or slow disks will be obvious when you need to check them. + +Join the Network World communities on [Facebook][2] and [LinkedIn][3] to comment on topics that are top of mind. + +-------------------------------------------------------------------------------- + +via: https://www.networkworld.com/article/3330497/linux/linux-commands-for-measuring-disk-activity.html + +作者：[Sandra Henry-Stocker][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.networkworld.com/author/Sandra-Henry_Stocker/ +[b]: https://github.com/lujun9972 +[1]: https://www.networkworld.com/article/3291616/linux/examining-linux-system-performance-with-dstat.html +[2]: https://www.facebook.com/NetworkWorld/ +[3]: https://www.linkedin.com/company/network-world diff --git a/sources/tech/20181231 Easily Upload Text Snippets To Pastebin-like Services From Commandline.md b/sources/tech/20181231 Easily Upload Text Snippets To Pastebin-like Services From Commandline.md new file mode 100644 index 0000000000..58b072f2fc --- /dev/null +++ b/sources/tech/20181231 Easily Upload Text Snippets To Pastebin-like Services From Commandline.md @@ -0,0 +1,259 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Easily Upload Text Snippets To Pastebin-like Services From Commandline) +[#]: via: (https://www.ostechnix.com/how-to-easily-upload-text-snippets-to-pastebin-like-services-from-commandline/) +[#]: author: (SK https://www.ostechnix.com/author/sk/) + +Easily Upload Text Snippets To Pastebin-like Services From Commandline +====== + + + +Whenever there is need to share the code snippets online, the first one probably comes to our mind is Pastebin.com, the online text sharing site launched by **Paul Dixon** in 2002. Now, there are several alternative text sharing services available to upload and share text snippets, error logs, config files, a command’s output or any sort of text files. If you happen to share your code often using various Pastebin-like services, I do have a good news for you. Say hello to **Wgetpaste** , a command line BASH utility to easily upload text snippets to pastebin-like services. Using Wgetpaste script, anyone can quickly share text snippets to their friends, colleagues, or whoever wants to see/use/review the code from command line in Unix-like systems. + +### Installing Wgetpaste + +Wgetpaste is available in Arch Linux [Community] repository. To install it on Arch Linux and its variants like Antergos and Manjaro Linux, just run the following command: + +``` +$ sudo pacman -S wgetpaste +``` + +For other distributions, grab the source code from [**Wgetpaste website**][1] and install it manually as described below. + +First download the latest Wgetpaste tar file: + +``` +$ wget http://wgetpaste.zlin.dk/wgetpaste-2.28.tar.bz2 +``` + +Extract it: + +``` +$ tar -xvjf wgetpaste-2.28.tar.bz2 +``` + +It will extract the contents of the tar file in a folder named “wgetpaste-2.28”. + +Go to that directory: + +``` +$ cd wgetpaste-2.28/ +``` + +Copy the wgetpaste binary to your $PATH, for example **/usr/local/bin/**. + +``` +$ sudo cp wgetpaste /usr/local/bin/ +``` + +Finally, make it executable using command: + +``` +$ sudo chmod +x /usr/local/bin/wgetpaste +``` + +### Upload Text Snippets To Pastebin-like Services + +Uploading text snippets using Wgetpaste is trivial. Let me show you a few examples. + +**1\. Upload text files** + +To upload any text file using Wgetpaste, just run: + +``` +$ wgetpaste mytext.txt +``` + +This command will upload the contents of mytext.txt file. + +Sample output: + +``` +Your paste can be seen here: https://paste.pound-python.org/show/eO0aQjTgExP0wT5uWyX7/ +``` + + + +You can share the pastebin URL via any medium like mail, message, whatsapp or IRC etc. Whoever has this URL can visit it and view the contents of the text file in a web browser of their choice. + +Here is the contents of mytext.txt file in web browser: + + + +You can also use **‘tee’** command to display what is being pasted, instead of uploading them blindly. + +To do so, use **-t** option like below. + +``` +$ wgetpaste -t mytext.txt +``` + +![][3] + +**2. Upload text snippets to different services +** + +By default, Wgetpaste will upload the text snippets to **poundpython** ( +``` + +For example, if you want to use [Lodash][8] in your project, you can add it using Yarn like this: + +``` +yarn add lodash +yarn add v1.12.3 +info No lockfile found. +[1/4] Resolving packages… +[2/4] Fetching packages… +[3/4] Linking dependencies… +[4/4] Building fresh packages… +success Saved lockfile. +success Saved 1 new dependency. +info Direct dependencies +└─ [email protected] +info All dependencies +└─ [email protected] +Done in 2.67s. +``` + +And you can see that this dependency has been added automatically in the package.json file: + +``` +{ + "name": "test_yarn_proect", + "version": "0.1", + "description": "Test Yarn", + "main": "index.js", + "author": "abhishek", + "license": "MIT", + "dependencies": { + "lodash": "^4.17.11" + } +} +``` + +By default, Yarn will add the latest version of a package in the dependency. If you want to use a specific version, you may specify it while adding. + +As always, you can also update the package.json file manually. + +#### Upgrading dependencies with Yarn + +You can upgrade a particular dependency to its latest version with the following command: + +``` +yarn upgrade +``` + +It will see if the package in question has a newer version and will update it accordingly. + +You can also change the version of an already added dependency in the following manner: + +You can also upgrade all the dependencies of your project to their latest version with one single command: + +``` +yarn upgrade +``` + +It will check the versions of all the dependencies and will update them if there are any newer versions. + +#### Removing dependencies with Yarn + +You can remove a package from the dependencies of your project in this way: + +``` +yarn remove +``` + +#### Install all project dependencies + +If you made any changes to the project.json file, you should run either + +``` +yarn +``` + +or + +``` +yarn install +``` + +to install all the dependencies at once. + +### How to remove Yarn from Ubuntu or Debian + +I’ll complete this tutorial by mentioning the steps to remove Yarn from your system if you used the above steps to install it. If you ever realized that you don’t need Yarn anymore, you will be able to remove it. + +Use the following command to remove Yarn and its dependencies. + +``` +sudo apt purge yarn +``` + +You should also remove the Yarn repository from the repository list: + +``` +sudo rm /etc/apt/sources.list.d/yarn.list +``` + +The optional next step is to remove the GPG key you had added to the trusted keys. But for that, you need to know the key. You can get that using the apt-key command: + +Warning: apt-key output should not be parsed (stdout is not a terminal) pub rsa4096 2016-10-05 [SC] 72EC F46A 56B4 AD39 C907 BBB7 1646 B01B 86E5 0310 uid [ unknown] Yarn Packaging + +Warning: apt-key output should not be parsed (stdout is not a terminal) pub rsa4096 2016-10-05 [SC] 72EC F46A 56B4 AD39 C907 BBB7 1646 B01B 86E5 0310 uid [ unknown] Yarn Packaging yarn@dan.cx sub rsa4096 2016-10-05 [E] sub rsa4096 2019-01-02 [S] [expires: 2020-02-02] + +The key here is the last 8 characters of the GPG key’s fingerprint in the line starting with pub. + +So, in my case, the key is 86E50310 and I’ll remove it using this command: + +``` +sudo apt-key del 86E50310 +``` + +You’ll see an OK in the output and the GPG key of Yarn package will be removed from the list of GPG keys your system trusts. + +I hope this tutorial helped you to install Yarn on Ubuntu, Debian, Linux Mint, elementary OS etc. I provided some basic Yarn commands to get you started along with complete steps to remove Yarn from your system. + +I hope you liked this tutorial and if you have any questions or suggestions, please feel free to leave a comment below. + + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/install-yarn-ubuntu + +作者：[Abhishek Prakash][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://itsfoss.com/author/abhishek/ +[b]: https://github.com/lujun9972 +[1]: https://yarnpkg.com/lang/en/ +[2]: https://code.fb.com/ +[3]: https://www.npmjs.com/ +[4]: https://itsfoss.com/checksum-tools-guide-linux/ +[5]: https://itsfoss.com/install-nodejs-ubuntu/ +[6]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/yarn-js-ubuntu-debian.jpeg?resize=800%2C450&ssl=1 +[7]: https://itsfoss.com/update-ubuntu/ +[8]: https://lodash.com/ diff --git a/sources/tech/20190104 Search, Study And Practice Linux Commands On The Fly.md b/sources/tech/20190104 Search, Study And Practice Linux Commands On The Fly.md new file mode 100644 index 0000000000..fa92d3450a --- /dev/null +++ b/sources/tech/20190104 Search, Study And Practice Linux Commands On The Fly.md @@ -0,0 +1,223 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Search, Study And Practice Linux Commands On The Fly!) +[#]: via: (https://www.ostechnix.com/search-study-and-practice-linux-commands-on-the-fly/) +[#]: author: (SK https://www.ostechnix.com/author/sk/) + +Search, Study And Practice Linux Commands On The Fly! +====== + + + +The title may look like sketchy and click bait. Allow me to explain what I am about to explain in this tutorial. Let us say you want to download an archive file, extract it and move the file from one location to another from command line. As per the above scenario, we may need at least three Linux commands, one for downloading the file, one for extracting the downloaded file and one for moving the file. If you’re intermediate or advanced Linux user, you could do this easily with an one-liner command or a script in few seconds/minutes. But, if you are a noob who don’t know much about Linux commands, you might need little help. + +Of course, a quick google search may yield many results. Or, you could use [**man pages**][1]. But some man pages are really long, comprehensive and lack in useful example. You might need to scroll down for quite a long time when you’re looking for a particular information on the specific flags/options. Thankfully, there are some [**good alternatives to man pages**][2], which are focused on mostly practical commands. One such good alternative is **TLDR pages**. Using TLDR pages, we can quickly and easily learn a Linux command with practical examples. To access the TLDR pages, we require a TLDR client. There are many clients available. Today, we are going to learn about one such client named **“Tldr++”**. + +Tldr++ is a fast and interactive tldr client written with **Go** programming language. Unlike the other Tldr clients, it is fully interactive. That means, you can pick a command, read all examples , and immediately run any command without having to retype or copy/paste each command in the Terminal. Still don’t get it? No problem. Read on to learn and practice Linux commands on the fly. + +### Install Tldr++ + +Installing Tldr++ is very simple. Download tldr++ latest version from the [**releases page**][3]. Extract it and move the tldr++ binary to your $PATH. + +``` +$ wget https://github.com/isacikgoz/tldr/releases/download/v0.5.0/tldr_0.5.0_linux_amd64.tar.gz + +$ tar xzf tldr_0.5.0_linux_amd64.tar.gz + +$ sudo mv tldr /usr/local/bin + +$ sudo chmod +x /usr/local/bin/tldr +``` + +Now, run ‘tldr’ binary to populate the tldr pages in your local system. + +``` +$ tldr +``` + +Sample output: + +``` +Enumerating objects: 6, done. +Counting objects: 100% (6/6), done. +Compressing objects: 100% (6/6), done. +Total 18157 (delta 0), reused 3 (delta 0), pack-reused 18151 +Successfully cloned into: /home/sk/.local/share/tldr +``` + + + +Tldr++ is available in AUR. If you’re on Arch Linux, you can install it using any AUR helper, for example [**YaY**][4]. Make sure you have removed any existing tldr client from your system and run the following command to install tldr++. + +``` +$ yay -S tldr++ +``` + +Alternatively, you can build from source as described below. Since Tldr++ is written using Go language, make sure you have installed it on your Linux box. If it isn’t installed yet, refer the following guide. + ++ [How To Install Go Language In Linux](https://www.ostechnix.com/install-go-language-linux/) + +After installing Go, run the following command to install Tldr++. + +``` +$ go get -u github.com/isacikgoz/tldr +``` + +This command will download the contents of tldr repository in a folder named **‘go’** in the current working directory. + +Now run the ‘tldr’ binary to populate all tldr pages in your local system using command: + +``` +$ go/bin/tldr +``` + +Sample output: + +![][6] + +Finally, copy the tldr binary to your PATH. + +``` +$ sudo mv tldr /usr/local/bin +``` + +It is time to see some examples. + +### Tldr++ Usage + +Type ‘tldr’ command without any options to display all command examples in alphabetical order. + +![][7] + +Use the **UP/DOWN arrows** to navigate through the commands, type any letters to search or type a command name to view the examples of that respective command. Press **?** for more and **Ctrl+c** to return/exit. + +To display the example commands of a specific command, for example **apt** , simply do: + +``` +$ tldr apt +``` + +![][8] + +Choose any example command from the list and hit ENTER. You will see a *** symbol** before the selected command. For example, I choose the first command i.e ‘sudo apt update’. Now, it will ask you whether to continue or not. If the command is correct, just type ‘y’ to continue and type your sudo password to run the selected command. + +![][9] + +See? You don’t need to copy/paste or type the actual command in the Terminal. Just choose it from the list and run on the fly! + +There are hundreds of Linux command examples are available in Tldr pages. You can choose one or two commands per day and learn them thoroughly. And keep this practice everyday to learn as much as you can. + +### Learn And Practice Linux Commands On The Fly Using Tldr++ + +Now think of the scenario that I mentioned in the first paragraph. You want to download a file, extract it and move it to different location and make it executable. Let us see how to do it interactively using Tldr++ client. + +**Step 1 – Download a file from Internet** + +To download a file from command line, we mostly use **‘curl’** or **‘wget’** commands. Let me use ‘wget’ to download the file. To open tldr page of wget command, just run: + +``` +$ tldr wget +``` + +Here is the examples of wget command. + + + +You can use **UP/DOWN** arrows to go through the list of commands. Once you choose the command of your choice, press ENTER. Here I chose the first command. + +Now, enter the path of the file to download. + + + +You will then be asked to confirm if it is the correct command or not. If the command is correct, simply type ‘yes’ or ‘y’ to start downloading the file. + +![][10] + +We have downloaded the file. Let us go ahead and extract this file. + +**Step 2 – Extract downloaded archive** + +We downloaded the **tar.gz** file. So I am going to open the ‘tar’ tldr page. + +``` +$ tldr tar +``` + +You will see the list of example commands. Go through the examples and find which command is suitable to extract tar.gz(gzipped archive) file and hit ENTER key. In our case, it is the third command. + +![][11] + +Now, you will be prompted to enter the path of the tar.gz file. Just type the path and hit ENTER key. Tldr++ supports smart file suggestions. That means it will suggest the file name automatically as you type. Just press TAB key for auto-completion. + +![][12] + +If you downloaded the file to some other location, just type the full path, for example **/home/sk/Downloads/tldr_0.5.0_linux_amd64.tar.gz.** + +Once you enter the path of the file to extract, press ENTER and then, type ‘y’ to confirm. + +![][13] + +**Step 3 – Move file from one location to another** + +We extracted the archive. Now we need to move the file to another location. To move the files from one location to another, we use ‘mv’ command. So, let me open the tldr page for mv command. + +``` +$ tldr mv +``` + +Choose the correct command to move the files from one location to another. In our case, the first command will work, so let me choose it. + +![][14] + +Type the path of the file that you want to move and enter the destination path and hit ENTER key. + +![][15] + +**Note:** Type **y!** or **yes!** to run command with **sudo** privileges. + +As you see in the above screenshot, I moved the file named **‘tldr’** to **‘/usr/local/bin/’** location. + +For more details, refer the project’s GitHub page given at the end. + + +### Conclusion + +Don’t get me wrong. **Man pages are great!** There is no doubt about it. But, as I already said, many man pages are comprehensive and doesn’t have useful examples. There is no way I could memorize all lengthy commands with tricky flags. Some times I spent much time on man pages and remained clueless. The Tldr pages helped me to find what I need within few minutes. Also, we use some commands once in a while and then we forget them completely. Tldr pages on the other hand actually helps when it comes to using commands we rarely use. Tldr++ client makes this task much easier with smart user interaction. Give it a go and let us know what you think about this tool in the comment section below. + +And, that’s all. More good stuffs to come. Stay tuned! + +Good luck! + + + +-------------------------------------------------------------------------------- + +via: https://www.ostechnix.com/search-study-and-practice-linux-commands-on-the-fly/ + +作者：[SK][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.ostechnix.com/author/sk/ +[b]: https://github.com/lujun9972 +[1]: https://www.ostechnix.com/learn-use-man-pages-efficiently/ +[2]: https://www.ostechnix.com/3-good-alternatives-man-pages-every-linux-user-know/ +[3]: https://github.com/isacikgoz/tldr/releases +[4]: https://www.ostechnix.com/yay-found-yet-another-reliable-aur-helper/ +[5]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[6]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-1.png +[7]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-11.png +[8]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-12.png +[9]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-13.png +[10]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-4.png +[11]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-6.png +[12]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-7.png +[13]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-8.png +[14]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-9.png +[15]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-10.png diff --git a/sources/tech/20190105 Setting up an email server, part 1- The Forwarder.md b/sources/tech/20190105 Setting up an email server, part 1- The Forwarder.md new file mode 100644 index 0000000000..c6c520e339 --- /dev/null +++ b/sources/tech/20190105 Setting up an email server, part 1- The Forwarder.md @@ -0,0 +1,224 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Setting up an email server, part 1: The Forwarder) +[#]: via: (https://blog.jak-linux.org/2019/01/05/setting-up-an-email-server-part1/) +[#]: author: (Julian Andres Klode https://blog.jak-linux.org/) + +Setting up an email server, part 1: The Forwarder +====== + +This week, I’ve been working on rolling out mail services on my server. I started working on a mail server setup at the end of November, while the server was not yet in use, but only for about two days, and then let it rest. + +As my old shared hosting account expired on January 1, I had to move mail forwarding duties over to the new server. Yes forwarding - I do plan to move hosting the actual email too, but at the moment it’s “just” forwarding to gmail. + +### The Software + +As you might know from the web server story, my server runs on Ubuntu 18.04. I set up a mail server on this system using + + * [Postfix][1] for SMTP duties (warning, they oddly do not have an https page) + * [rspamd][2] for spam filtering, and signing DKIM / ARC + * [bind9][3] for DNS resolving + * [postsrsd][4] for SRS + + + +You might wonder why bind9 is in there. It turns out that DNS blacklists used by spam filters block the caching DNS servers you usually use, so you have to use your own recursive DNS server. Ubuntu offers you the choice between bind9 and dnsmasq in main, and it seems like bind9 is more appropriate here than dnsmasq. + +### Setting up postfix + +Most of the postfix configuration is fairly standard. So, let’s skip TLS configuration and outbound SMTP setups (this is email, and while they support TLS, it’s all optional, so let’s not bother that much here). + +The most important part is restrictions in `main.cf`. + +First of all, relay restrictions prevent us from relaying emails to weird domains: + +``` +# Relay Restrictions +smtpd_relay_restrictions = reject_non_fqdn_recipient reject_unknown_recipient_domain permit_mynetworks permit_sasl_authenticated defer_unauth_destination +``` + +We also only accept mails from hosts that know their own full qualified name: + +``` +# Helo restrictions (hosts not having a proper fqdn) +smtpd_helo_required = yes +smtpd_helo_restrictions = permit_mynetworks reject_invalid_helo_hostname reject_non_fqdn_helo_hostname reject_unknown_helo_hostname +``` + +We also don’t like clients (other servers) that send data too early, or have an unknown hostname: + +``` +smtpd_data_restrictions = reject_unauth_pipelining +smtpd_client_restrictions = permit_mynetworks reject_unknown_client_hostname +``` + +I also set up a custom apparmor profile that’s pretty lose, I plan to migrate to the one in the apparmor git eventually but it needs more testing and some cleanup. + +### Sender rewriting scheme + +For SRS using postsrsd, we define the `SRS_DOMAIN` in `/etc/default/postsrsd` and then configure postfix to talk to it: + +``` +# Handle SRS for forwarding +recipient_canonical_maps = tcp:localhost:10002 +recipient_canonical_classes= envelope_recipient,header_recipient + +sender_canonical_maps = tcp:localhost:10001 +sender_canonical_classes = envelope_sender +``` + +This has a minor issue that it also rewrites the `Return-Path` when it delivers emails locally, but as I am only forwarding, I’m worrying about that later. + +### rspamd basics + +rspamd is a great spam filtering system. It uses a small core written in C and a bunch of Lua plugins, such as: + + * IP score, which keeps track of how good a specific server was in the past + * Replies, which can check whether an email is a reply to another one + * DNS blacklisting + * DKIM and ARC validation and signing + * DMARC validation + * SPF validation + + + +It also has a nice web UI: + +![rspamd web ui status][5] + +rspamd web ui status + +![rspamd web ui investigating a spam message][6] + +rspamd web ui investigating a spam message + +Setting up rspamd is quite easy. You basically just drop a bunch of configuration overrides into `/etc/rspamd/local.d` and you’re done. Heck, it mostly works out of the box. There’s a fancy `rspamadm configwizard` too. + +What you do want for rspamd is a redis server. redis is needed in [many places][7], such as rate limiting, greylisting, dmarc, reply tracking, ip scoring, neural networks. + +I made a few changes to the defaults: + + * I enabled subject rewriting instead of adding headers, so spam mail subjects get `[SPAM]` prepended, in `local.d/actions.conf`: + +``` + reject = 15; +rewrite_subject = 6; +add_header = 6; +greylist = 4; +subject = "[SPAM] %s"; +``` + + * I set `autolearn = true;` in `local.d/classifier-bayes.conf` to make it learn that an email that has a score of at least 15 (those that are rejected) is spam, and emails with negative scores are ham. + + * I set `extended_spam_headers = true;` in `local.d/milter_headers.conf` to get a report from rspamd in the header seeing the score and how the score came to be. + + + + +### ARC setup + +[ARC][8] is the ‘Authenticated Received Chain’ and is currently a DMARC working group work item. It allows forwarders / mailing lists to authenticate their forwarding of the emails and the checks they have performed. + +rspamd is capable of validating and signing emails with ARC, but I’m not sure how much influence ARC has on gmail at the moment, for example. + +There are three parts to setting up ARC: + + 1. Generate a DKIM key pair (use `rspamadm dkim_keygen`) + 2. Setup rspamd to sign incoming emails using the private key + 3. Add a DKIM `TXT` record for the public key. `rspamadm` helpfully tells you how it looks like. + + + +For step two, what we need to do is configure `local.d/arc.conf`. You can basically use the example configuration from the [rspamd page][9], the key point for signing incoming email is to specifiy `sign_incoming = true;` and `use_domain_sign_inbound = "recipient";` (FWIW, none of these options are documented, they are fairly new, and nobody updated the documentation for them). + +My configuration looks like this at the moment: + +``` +# If false, messages with empty envelope from are not signed +allow_envfrom_empty = true; +# If true, envelope/header domain mismatch is ignored +allow_hdrfrom_mismatch = true; +# If true, multiple from headers are allowed (but only first is used) +allow_hdrfrom_multiple = false; +# If true, username does not need to contain matching domain +allow_username_mismatch = false; +# If false, messages from authenticated users are not selected for signing +auth_only = true; +# Default path to key, can include '$domain' and '$selector' variables +path = "${DBDIR}/arc/$domain.$selector.key"; +# Default selector to use +selector = "arc"; +# If false, messages from local networks are not selected for signing +sign_local = true; +# +sign_inbound = true; +# Symbol to add when message is signed +symbol_signed = "ARC_SIGNED"; +# Whether to fallback to global config +try_fallback = true; +# Domain to use for ARC signing: can be "header" or "envelope" +use_domain = "header"; +use_domain_sign_inbound = "recipient"; +# Whether to normalise domains to eSLD +use_esld = true; +# Whether to get keys from Redis +use_redis = false; +# Hash for ARC keys in Redis +key_prefix = "ARC_KEYS"; +``` + +This would also sign any outgoing email, but I’m not sure that’s necessary - my understanding is that we only care about ARC when forwarding/receiving incoming emails, not when sending them (at least that’s what gmail does). + +### Other Issues + +There are few other things to keep in mind when running your own mail server. I probably don’t know them all yet, but here we go: + + * You must have a fully qualified hostname resolving to a public IP address + + * Your public IP address must resolve back to the fully qualified host name + + * Again, you should run a recursive DNS resolver so your DNS blacklists work (thanks waldi for pointing that out) + + * Setup an SPF record. Mine looks like this: + +`jak-linux.org. 3600 IN TXT "v=spf1 +mx ~all"` + +this states that all my mail servers may send email, but others probably should not (a softfail). Not having an SPF record can punish you; for example, rspamd gives missing SPF and DKIM a score of 1. + + * All of that software is sandboxed using AppArmor. Makes you question its security a bit less! + + + + +### Source code, outlook + +As always, you can find the Ansible roles on [GitHub][10]. Feel free to point out bugs! 😉 + +In the next installment of this series, we will be looking at setting up Dovecot, and configuring DKIM. We probably also want to figure out how to run notmuch on the server, keep messages in matching maildirs, and have my laptop synchronize the maildir and notmuch state with the server. Ugh, sounds like a lot of work. + +-------------------------------------------------------------------------------- + +via: https://blog.jak-linux.org/2019/01/05/setting-up-an-email-server-part1/ + +作者：[Julian Andres Klode][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://blog.jak-linux.org/ +[b]: https://github.com/lujun9972 +[1]: http://www.postfix.org/ +[2]: https://rspamd.com/ +[3]: https://www.isc.org/downloads/bind/ +[4]: https://github.com/roehling/postsrsd +[5]: https://blog.jak-linux.org/2019/01/05/setting-up-an-email-server-part1/rspamd-status.png +[6]: https://blog.jak-linux.org/2019/01/05/setting-up-an-email-server-part1/rspamd-spam.png +[7]: https://rspamd.com/doc/configuration/redis.html +[8]: http://arc-spec.org/ +[9]: https://rspamd.com/doc/modules/arc.html +[10]: https://github.com/julian-klode/ansible.jak-linux.org diff --git a/sources/tech/20190107 Aliases- To Protect and Serve.md b/sources/tech/20190107 Aliases- To Protect and Serve.md new file mode 100644 index 0000000000..783c59dc41 --- /dev/null +++ b/sources/tech/20190107 Aliases- To Protect and Serve.md @@ -0,0 +1,176 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Aliases: To Protect and Serve) +[#]: via: (https://www.linux.com/blog/learn/2019/1/aliases-protect-and-serve) +[#]: author: (Paul Brown https://www.linux.com/users/bro66) + +Aliases: To Protect and Serve +====== + + + +Happy 2019! Here in the new year, we’re continuing our series on aliases. By now, you’ve probably read our [first article on aliases][1], and it should be quite clear how they are the easiest way to save yourself a lot of trouble. You already saw, for example, that they helped with muscle-memory, but let's see several other cases in which aliases come in handy. + +### Aliases as Shortcuts + +One of the most beautiful things about Linux's shells is how you can use zillions of options and chain commands together to carry out really sophisticated operations in one fell swoop. All right, maybe beauty is in the eye of the beholder, but let's agree that this feature published practical. + +The downside is that you often come up with recipes that are often hard to remember or cumbersome to type. Say space on your hard disk is at a premium and you want to do some New Year's cleaning. Your first step may be to look for stuff to get rid off in you home directory. One criteria you could apply is to look for stuff you don't use anymore. `ls` can help with that: + +``` +ls -lct +``` + +The instruction above shows the details of each file and directory (`-l`) and also shows when each item was last accessed (`-c`). It then orders the list from most recently accessed to least recently accessed (`-t`). + +Is this hard to remember? You probably don’t use the `-c` and `-t` options every day, so perhaps. In any case, defining an alias like + +``` +alias lt='ls -lct' +``` + +will make it easier. + +Then again, you may want to have the list show the oldest files first: + +``` +alias lo='lt -F | tac' +``` + +![aliases][3] + +Figure 1: The lt and lo aliases in action. + +[Used with permission][4] + +There are a few interesting things going here. First, we are using an alias (`lt`) to create another alias -- which is perfectly okay. Second, we are passing a new parameter to `lt` (which, in turn gets passed to `ls` through the definition of the `lt` alias). + +The `-F` option appends special symbols to the names of items to better differentiate regular files (that get no symbol) from executable files (that get an `*`), files from directories (end in `/`), and all of the above from links, symbolic and otherwise (that end in an `@` symbol). The `-F` option is throwback to the days when terminals where monochrome and there was no other way to easily see the difference between items. You use it here because, when you pipe the output from `lt` through to `tac` you lose the colors from `ls`. + +The third thing to pay attention to is the use of piping. Piping happens when you pass the output from an instruction to another instruction. The second instruction can then use that output as its own input. In many shells (including Bash), you pipe something using the pipe symbol (`|`). + +In this case, you are piping the output from `lt -F` into `tac`. `tac`'s name is a bit of a joke. You may have heard of `cat`, the instruction that was nominally created to con _cat_ enate files together, but that in practice is used to print out the contents of a file to the terminal. `tac` does the same, but prints out the contents it receives in reverse order. Get it? `cat` and `tac`. Developers, you so funny! + +The thing is both `cat` and `tac` can also print out stuff piped over from another instruction, in this case, a list of files ordered chronologically. + +So... after that digression, what comes out of the other end is the list of files and directories of the current directory in inverse order of freshness. + +The final thing you have to bear in mind is that, while `lt` will work the current directory and any other directory... + +``` +# This will work: +lt +# And so will this: +lt /some/other/directory +``` + +... `lo` will only work with the current directory: + +``` +# This will work: +lo +# But this won't: +lo /some/other/directory +``` + +This is because Bash expands aliases into their components. When you type this: + +``` +lt /some/other/directory +``` + +Bash REALLY runs this: + +``` +ls -lct /some/other/directory +``` + +which is a valid Bash command. + +However, if you type this: + +``` +lo /some/other/directory +``` + +Bash tries to run this: + +``` +ls -lct -F | tac /some/other/directory +``` + +which is not a valid instruction, because `tac` mainly because _/some/other/directory_ is a directory, and `cat` and `tac` don't do directories. + +### More Alias Shortcuts + + * `alias lll='ls -R'` prints out the contents of a directory and then drills down and prints out the contents of its subdirectories and the subdirectories of the subdirectories, and so on and so forth. It is a way of seeing everything you have under a directory. + + * `mkdir='mkdir -pv'` let's you make directories within directories all in one go. With the base form of `mkdir`, to make a new directory containing a subdirectory you have to do this: + +``` + mkdir newdir +mkdir newdir/subdir +``` + +Or this: + +``` +mkdir -p newdir/subdir +``` + +while with the alias you would only have to do this: + +``` +mkdir newdir/subdir +``` + +Your new `mkdir` will also tell you what it is doing while is creating new directories. + + + + +### Aliases as Safeguards + +The other thing aliases are good for is as safeguards against erasing or overwriting your files accidentally. At this stage you have probably heard the legendary story about the new Linux user who ran: + +``` +rm -rf / +``` + +as root, and nuked the whole system. Then there's the user who decided that: + +``` +rm -rf /some/directory/ * +``` + +was a good idea and erased the complete contents of their home directory. Notice how easy it is to overlook that space separating the directory path and the `*`. + +Both things can be avoided with the `alias rm='rm -i'` alias. The `-i` option makes `rm` ask the user whether that is what they really want to do and gives you a second chance before wreaking havoc in your file system. + +The same goes for `cp`, which can overwrite a file without telling you anything. Create an alias like `alias cp='cp -i'` and stay safe! + +### Next Time + +We are moving more and more into scripting territory. Next time, we'll take the next logical step and see how combining instructions on the command line gives you really interesting and sophisticated solutions to everyday admin problems. + + +-------------------------------------------------------------------------------- + +via: https://www.linux.com/blog/learn/2019/1/aliases-protect-and-serve + +作者：[Paul Brown][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.linux.com/users/bro66 +[b]: https://github.com/lujun9972 +[1]: https://www.linux.com/blog/learn/2019/1/aliases-protect-and-serve +[2]: https://www.linux.com/files/images/fig01png-0 +[3]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/fig01_0.png?itok=crqTm_va (aliases) +[4]: https://www.linux.com/licenses/category/used-permission diff --git a/sources/tech/20190107 Different Ways To Update Linux Kernel For Ubuntu.md b/sources/tech/20190107 Different Ways To Update Linux Kernel For Ubuntu.md new file mode 100644 index 0000000000..32a6a7dd3e --- /dev/null +++ b/sources/tech/20190107 Different Ways To Update Linux Kernel For Ubuntu.md @@ -0,0 +1,232 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Different Ways To Update Linux Kernel For Ubuntu) +[#]: via: (https://www.ostechnix.com/different-ways-to-update-linux-kernel-for-ubuntu/) +[#]: author: (SK https://www.ostechnix.com/author/sk/) + +Different Ways To Update Linux Kernel For Ubuntu +====== + + + +In this guide, we have given 7 different ways to update Linux kernel for Ubuntu. Among the 7 methods, five methods requires system reboot to apply the new Kernel and two methods don’t. Before updating Linux Kernel, it is **highly recommended to backup your important data!** All methods mentioned here are tested on Ubuntu OS only. We are not sure if they will work on other Ubuntu flavors (Eg. Xubuntu) and Ubuntu derivatives (Eg. Linux Mint). + +### Part A – Kernel Updates with reboot + +The following methods requires you to reboot your system to apply the new Linux Kernel. All of the following methods are recommended for personal or testing systems. Again, please backup your important data, configuration files and any other important stuff from your Ubuntu system. + +#### Method 1 – Update the Linux Kernel with dpkg (The manual way) + +This method helps you to manually download and install the latest available Linux kernel from **[kernel.ubuntu.com][1]** website. If you want to install most recent version (either stable or release candidate), this method will help. Download the Linux kernel version from the above link. As of writing this guide, the latest available version was **5.0-rc1** and latest stable version was **v4.20**. + +![][3] + +Click on the Linux Kernel version link of your choice and find the section for your architecture (‘Build for XXX’). In that section, download the two files with these patterns (where X.Y.Z is the highest version): + + 1. linux-image-*X.Y.Z*-generic-*.deb + 2. linux-modules-X.Y.Z*-generic-*.deb + + + +In a terminal, change directory to where the files are and run this command to manually install the kernel: + +``` +$ sudo dpkg --install *.deb +``` + +Reboot to use the new kernel: + +``` +$ sudo reboot +``` + +Check the kernel is as expected: + +``` +$ uname -r +``` + +For step by step instructions, please check the section titled under “Install Linux Kernel 4.15 LTS On DEB based systems” in the following guide. + ++ [Install Linux Kernel 4.15 In RPM And DEB Based Systems](https://www.ostechnix.com/install-linux-kernel-4-15-rpm-deb-based-systems/) + +The above guide is specifically written for 4.15 version. However, all the steps are same for installing latest versions too. + +**Pros:** No internet needed (You can download the Linux Kernel from any system). + +**Cons:** Manual update. Reboot necessary. + +#### Method 2 – Update the Linux Kernel with apt-get (The recommended method) + +This is the recommended way to install latest Linux kernel on Ubuntu-like systems. Unlike the previous method, this method will download and install latest Kernel version from Ubuntu official repositories instead of **kernel.ubuntu.com** website.. + +To update the whole system including the Kernel, just do: + +``` +$ sudo apt-get update + +$ sudo apt-get upgrade +``` + +If you want to update the Kernel only, run: + +``` +$ sudo apt-get upgrade linux-image-generic +``` + +**Pros:** Simple. Recommended method. + +**Cons:** Internet necessary. Reboot necessary. + +Updating Kernel from official repositories will mostly work out of the box without any problems. If it is the production system, this is the recommended way to update the Kernel. + +Method 1 and 2 requires user intervention to update Linux Kernels. The following methods (3, 4 & 5) are mostly automated. + +#### Method 3 – Update the Linux Kernel with Ukuu + +**Ukuu** is a Gtk GUI and command line tool that downloads the latest main line Linux kernel from **kernel.ubuntu.com** , and install it automatically in your Ubuntu desktop and server editions. Ukku is not only simplifies the process of manually downloading and installing new Kernels, but also helps you to safely remove the old and unnecessary Kernels. For more details, refer the following guide. + ++ [Ukuu – An Easy Way To Install And Upgrade Linux Kernel In Ubuntu-based Systems](https://www.ostechnix.com/ukuu-an-easy-way-to-install-and-upgrade-linux-kernel-in-ubuntu-based-systems/) + +**Pros:** Easy to install and use. Automatically installs main line Kernel. + +**Cons:** Internet necessary. Reboot necessary. + +#### Method 4 – Update the Linux Kernel with UKTools + +Just like Ukuu, the **UKTools** also fetches the latest stable Kernel from from **kernel.ubuntu.com** site and installs it automatically on Ubuntu and its derivatives like Linux Mint. More details about UKTools can be found in the link given below. + ++ [UKTools – Upgrade Latest Linux Kernel In Ubuntu And Derivatives](https://www.ostechnix.com/uktools-upgrade-latest-linux-kernel-in-ubuntu-and-derivatives/) + +**Pros:** Simple. Automated. + +**Cons:** Internet necessary. Reboot necessary. + +#### Method 5 – Update the Linux Kernel with Linux Kernel Utilities + +**Linux Kernel Utilities** is yet another program that makes the process of updating Linux kernel easy in Ubuntu-like systems. It is actually a set of BASH shell scripts used to compile and/or update latest Linux kernels for Debian and derivatives. It consists of three utilities, one for manually compiling and installing Kernel from source from [**http://www.kernel.org**][4] website, another for downloading and installing pre-compiled Kernels from from ** /.kodi/userdata/advancedsettings.xml**. This file can contain a lot of very advanced, tweakable settings. My devices have these settings: + +``` + + +``` + +The **< cache>** section—which sets how much of a file Kodi will buffer over the network— is optional in this scenario. See the [Kodi wiki][9] for a full breakdown of this file and its options. + +Once the configuration is complete, it's a good idea to close and reopen Kodi to make sure the settings are applied. + +The final step is configuring all the Kodi clients to use the same network share for all their content. Only one client needs to scrap/refresh the metadata if everything is created successfully. When data is collected, you should see that Kodi creates a new database on your SQL server: + +``` +[kodi@kodi-mysql ~]$ mysql -u root -p +Enter password: +Welcome to the MariaDB monitor. Commands end with ; or \g. +Your MariaDB connection id is 180 +Server version: 10.1.37-MariaDB MariaDB Server + +Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others. + +Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. + +MariaDB [(none)]> show databases; ++--------------------+ +| Database | ++--------------------+ +| MyVideos107 | +| information_schema | +| mysql | +| performance_schema | ++--------------------+ +4 rows in set (0.00 sec) +``` + +### Wrapping up + +This article walked through how to get up and running with the basic functionality of Kodi. You should be able to add content and pull down metadata to make browsing your media more convenient. + +You also know how to search for, install, and potentially configure add-ons for additional features. Be extra careful when downloading add-ons, as they are provided by the community at large and not the core developers. It's best to use add-ons only from organizations or companies you trust. + +And you know a bit about sharing metadata across multiple devices. You've been introduced to **advancedsettings.xml** ; hopefully it has piqued your interest. Kodi has a lot of dials and knobs to turn, and you can squeeze a lot of performance and functionality out of the platform with enough experimentation. + +Are you interested in doing more tweaking? What are some of your favorite add-ons or settings? Do you want to know how to change the user interface? What are some of your favorite skins? Let me know in the comments! + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/manage-your-media-kodi + +作者：[Steve Ovens][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/stratusss +[b]: https://github.com/lujun9972 +[1]: https://en.wikipedia.org/wiki/ISO_image +[2]: https://kodi.tv/ +[3]: https://kodi.wiki/view/HOW-TO:Install_Kodi_for_Linux#Fedora +[4]: https://en.wikipedia.org/wiki/Server_Message_Block +[5]: https://en.wikipedia.org/wiki/Zero-configuration_networking +[6]: https://www.plex.tv +[7]: https://www.samba.org/ +[8]: https://wiki.archlinux.org/index.php/MySQL +[9]: https://kodi.wiki/view/Advancedsettings.xml diff --git a/sources/tech/20190107 Testing isn-t everything.md b/sources/tech/20190107 Testing isn-t everything.md new file mode 100644 index 0000000000..b2a2daaaac --- /dev/null +++ b/sources/tech/20190107 Testing isn-t everything.md @@ -0,0 +1,135 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Testing isn't everything) +[#]: via: (https://arp242.net/weblog/testing.html) +[#]: author: (Martin Tournoij https://arp242.net/) + +Testing isn't everything +====== + +This is adopted from a discussion about [Want to write good unit tests in go? Don’t panic… or should you?][1] While this mainly talks about Go a lot of the points also apply to other languages. + +Some of the most difficult code I’ve worked with is code that is “easily testable”. Code that abstracts everything to the point where you have no idea what’s going on, just so that it can add a “unit test” to what would otherwise be a very straightforward function. DHH called this [Test-induced design damage][2]. + +Testing is just one tool to make sure that your program works, out of several. Another very important tool is writing code in such a way that it is easy to understand and reason about (“simplicity”). + +Books that advocate extensive testing – such as Robert C. Martin’s Clean Code – were written, in part, as a response to ever more complex programs, where you read 1,000 lines of code but still had no idea what’s going on. I recently had to port a simple Java “emoji replacer” (😂 ➙ 😂) to Go. To ensure compatibility I looked up the implementation. It was a whole bunch of classes, factories, and whatnot which all just resulted in calling a regexp on a string. 🤷 + +In dynamic languages like Ruby and Python tests are important for a different reason, as something like this will “work” just fine: + +``` +if condition: + print('w00t') +else: + nonexistent_function() +``` + +Except of course if that `else` branch is entered. It’s easy to typo stuff, or mix stuff up. + +In Go, both of these problems are less of a concern. It has a good static type system, and the focus is on simple straightforward code that is easy to comprehend. Even for a number of dynamic languages there are optional typing systems (function annotations in Python, TypeScript for JavaScript). + +Sometimes you can do a straightforward implementation that doesn’t sacrifice anything for testability; great! But sometimes you have to strike a balance. For some code, not adding a unit test is fine. + +Intensive focus on “unit tests” can be incredibly damaging to a code base. Some codebases have a gazillion unit tests, which makes any change excessively time-consuming as you’re fixing up a whole bunch of tests for even trivial changes. Often times a lot of these tests are just duplicates; adding tests to every layer of a simple CRUD HTTP endpoint is a common example. In many apps it’s fine to just rely on a single integration test. + +Stuff like SQL mocks is another great example. It makes code more complex, harder to change, all so we can say we added a “unit test” to `select * from foo where x=?`. The worst part is, it doesn’t even test anything other than verifying you didn’t typo an SQL query. As soon as the test starts doing anything useful, such as verifying that it actually returns the correct rows from the database, the Unit Test purists will start complaining that it’s not a True Unit Test™ and that You’re Doing It Wrong™. +For most queries, the integration tests and/or manual tests are fine, and extensive SQL mocks are entirely superfluous at best, and harmful at worst. + +There are exceptions, of course; if you’ve got a lot of `if cond { q += "more sql" }` then adding SQL mocks to verify the correctness of that logic might be a good idea. Even in those cases a “non-unit unit test” (e.g. one that just accesses the database) is still a viable option. Integration tests are also still an option. A lot of applications don’t have those kind of complex queries anyway. + +One important reason for the focus on unit tests is to ensure test code runs fast. This was a response to massive test harnesses that take a day to run. This, again, is not really a problem in Go. All integration tests I’ve written run in a reasonable amount of time (several seconds at most, usually faster). The test cache introduced in Go 1.10 makes it even less of a concern. + +Last year a coworker refactored our ETag-based caching library. The old code was very straightforward and easy to understand, and while I’m not claiming it was guaranteed bug-free, it did work very well for a long time. + +It should have been written with some tests in place, but it wasn’t (I didn’t write the original version). Note that the code was not completely untested, as we did have integration tests. + +The refactored version is much more complex. Aside from the two weeks lost on refactoring a working piece of code to … another working piece of code (topic for another post), I’m not so convinced it’s actually that much better. I consider myself a reasonably accomplished and experienced programmer, with a reasonable knowledge and experience in Go. I think that in general, based on feedback from peers and performance reviews, I am at least a programmer of “average” skill level, if not more. + +If an average programmer has trouble comprehending what is in essence a handful of simple functions because there are so many layers of abstractions, then something has gone wrong. The refactor traded one tool to verify correctness (simplicity) with another (testing). Simplicity is hardly a guarantee to ensure correctness, but neither are unit tests. Ideally, we should do both. + +Postscript: the refactor introduced a bug and removed a feature that was useful, but is now harder to add, not in the least because the code is much more complex. + +All units working correctly gives exactly zero guarantees that the program is working correctly. A lot of logic errors won’t be caught because the logic consists of several units working together. So you need integration tests, and if the integration tests duplicate half of your unit tests, then why bother with those unit tests? + +Test Driven Development (TDD) is also just one tool. It works well for some problems; not so much for others. In particular, I think that “forced to write code in tiny units” can be terribly harmful in some cases. Some code is just a serial script which says “do this, and then that, and then this”. Splitting that up in a whole bunch of “tiny units” can greatly reduce how easy the code is to understand, and thus harder to verify that it is correct. + +I’ve had to fix some Ruby code where everything was in tiny units – there is a strong culture of TDD in the Ruby community – and even though the units were easy to understand I found it incredibly hard to understand the application logic. If everything is split in “tiny units” then understanding how everything fits together to create an actual program that does something useful will be much harder. + +You see the same friction in the old microkernel vs. monolithic kernel debate, or the more recent microservices vs. monolithic app one. In principle splitting everything up in small parts sounds like a great idea, but in practice it turns out that making all the small parts work together is a very hard problem. A hybrid approach seems to work best for kernels and app design, balancing the advantages and downsides of both approaches. I think the same applies to code. + +To be clear, I am not against unit tests or TDD and claiming we should all gung-go cowboy code our way through life 🤠. I write unit tests and practice TDD, when it makes sense. My point is that unit tests and TDD are not the solution to every single last problem and should applied indiscriminately. This is why I use words such as “some” and “often” so frequently. + +This brings me to the topic of testing frameworks. I have never understood what problem libraries such as [goblin][3] are solving. How is this: + +``` +Expect(err).To(nil) +Expect(out).To(test.wantOut) +``` + +An improvement over this? + +``` +if err != nil { + t.Fatal(err) +} + +if out != tt.want { + t.Errorf("out: %q\nwant: %q", out, tt.want) +} +``` + +What’s wrong with `if` and `==`? Why do we need to abstract it? Note that with table-driven tests you’re only typing these checks once, so you’re saving just a few lines here. + +[Ginkgo][4] is even worse. It turns a very simple, straightforward, and understandable piece of code and doesn’t just abstract `if`, it also chops up the execution in several different functions (`BeforeEach()` and `DescribeTable()`). + +This is known as Behaviour-driven development (BDD). I am not entirely sure what to think of BDD. I am skeptical, but I’ve never properly used it in a large project so I’m hesitant to just dismiss it. Note that I said “properly”: most projects don’t really use BDD, they just use a library with a BDD syntax and shoehorn their testing code in to that. That’s ad-hoc BDD, or faux-BDD. + +Whatever merits BDD may have, they are not present simply because your testing code vaguely resembles BDD-style syntax. This on its own demonstrates that BDD is perhaps not a great idea for many projects. + +I think there are real problems with these BDD(-ish) test tools, as they obfuscate what you’re actually doing. No matter what, testing remains a matter of getting the output of a function and checking if that matches what you expected. No testing methodology is going to change that fundamental. The more layers you add on top of that, the harder it will be to debug. + +When determining if something is “easy” then my prime concern is not how easy something is to write, but how easy something is to debug when things fail. I will gladly spend a bit more effort writing things if that makes things a lot easier to debug. + +All code – including testing code – can fail in confusing, surprising, and unexpected ways (a “bug”), and then you’re expected to debug that code. The more complex the code, the harder it is to debug. + +You should expect all code – including testing code – to go through several debugging cycles. Note that with debugging cycle I don’t mean “there is a bug in the code you need to fix”, but rather “I need to look at this code to fix the bug”. + +In general, I already find testing code harder to debug than regular code, as the “code surface” tends to be larger. You have the testing code and the actual implementation code to think of. That’s a lot more than just thinking of the implementation code. + +Adding these abstractions means you will now also have to think about that, too! This might be okay if the abstractions would reduce the scope of what you have to think about, which is a common reason to add abstractions in regular code, but it doesn’t. It just adds more things to think about. + +So these are exactly the wrong kind of abstractions: they wrap and obfuscate, rather than separate concerns and reduce the scope. + +If you’re interested in soliciting contributions from other people in open source projects then making your tests understandable is a very important concern (it’s also important in business context, but a bit less so, as you’ve got actual time to train people). + +Seeing PRs with “here’s the code, it works, but I couldn’t figure out the tests, plz halp!” is not uncommon; and I’m fairly sure that at least a few people never even bothered to submit PRs just because they got stuck on the tests. I know I have. + +There is one open source project that I contributed to, and would like to contribute more to, but don’t because it’s just too hard to write and run tests. Every change is “write working code in 15 minutes, spend 45 minutes dealing with tests”. It’s … no fun at all. + +Writing good software is hard. I’ve got some ideas on how to do it, but don’t have a comprehensive view. I’m not sure if anyone really does. I do know that “always add unit tests” and “always practice TDD” isn’t the answer, in spite of them being useful concepts. To give an analogy: most people would agree that a free market is a good idea, but at the same time even most libertarians would agree it’s not the complete solution to every single problem (well, [some do][5], but those ideas are … rather misguided). + +You can mail me at [martin@arp242.net][6] or [create a GitHub issue][7] for feedback, questions, etc. + +-------------------------------------------------------------------------------- + +via: https://arp242.net/weblog/testing.html + +作者：[Martin Tournoij][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://arp242.net/ +[b]: https://github.com/lujun9972 +[1]: https://medium.com/@jens.neuse/want-to-write-good-unit-tests-in-go-dont-panic-or-should-you-ba3eb5bf4f51 +[2]: http://david.heinemeierhansson.com/2014/test-induced-design-damage.html +[3]: https://github.com/franela/goblin +[4]: https://github.com/onsi/ginkgo +[5]: https://en.wikipedia.org/wiki/Murray_Rothbard#Children's_rights_and_parental_obligations +[6]: mailto:martin@arp242.net +[7]: https://github.com/Carpetsmoker/arp242.net/issues/new diff --git a/sources/tech/20190108 Create your own video streaming server with Linux.md b/sources/tech/20190108 Create your own video streaming server with Linux.md new file mode 100644 index 0000000000..24dd44524d --- /dev/null +++ b/sources/tech/20190108 Create your own video streaming server with Linux.md @@ -0,0 +1,301 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Create your own video streaming server with Linux) +[#]: via: (https://opensource.com/article/19/1/basic-live-video-streaming-server) +[#]: author: (Aaron J.Prisk https://opensource.com/users/ricepriskytreat) + +Create your own video streaming server with Linux +====== +Set up a basic live streaming server on a Linux or BSD operating system. + + +Live video streaming is incredibly popular—and it's still growing. Platforms like Amazon's Twitch and Google's YouTube boast millions of users that stream and consume countless hours of live and recorded media. These services are often free to use but require you to have an account and generally hold your content behind advertisements. Some people don't need their videos to be available to the masses or just want more control over their content. Thankfully, with the power of open source software, anyone can set up a live streaming server. + +### Getting started + +In this tutorial, I'll explain how to set up a basic live streaming server with a Linux or BSD operating system. + +This leads to the inevitable question of system requirements. These can vary, as there are a lot of variables involved with live streaming, such as: + + * **Stream quality:** Do you want to stream in high definition or will standard definition fit your needs? + * **Viewership:** How many viewers are you expecting for your videos? + * **Storage:** Do you plan on keeping saved copies of your video stream? + * **Access:** Will your stream be private or open to the world? + + + +There are no set rules when it comes to system requirements, so I recommend you experiment and find what works best for your needs. I installed my server on a virtual machine with 4GB RAM, a 20GB hard drive, and a single Intel i7 processor core. + +This project uses the Real-Time Messaging Protocol (RTMP) to handle audio and video streaming. There are other protocols available, but I chose RTMP because it has broad support. As open standards like WebRTC become more compatible, I would recommend that route. + +It's also very important to know that "live" doesn't always mean instant. A video stream must be encoded, transferred, buffered, and displayed, which often adds delays. The delay can be shortened or lengthened depending on the type of stream you're creating and its attributes. + +### Setting up a Linux server + +You can use many different distributions of Linux, but I prefer Ubuntu, so I downloaded the [Ubuntu Server][1] edition for my operating system. If you prefer your server to have a graphical user interface (GUI), feel free to use [Ubuntu Desktop][2] or one of its many flavors. Then, I fired up the Ubuntu installer on my computer or virtual machine and chose the settings that best matched my environment. Below are the steps I took. + +Note: Because this is a server, you'll probably want to set some static network settings. + + + +After the installer finishes and your system reboots, you'll be greeted with a lovely new Ubuntu system. As with any newly installed operating system, install any updates that are available: + +``` +sudo apt update +sudo apt upgrade +``` + +This streaming server will use the very powerful and versatile Nginx web server, so you'll need to install it: + +``` +sudo apt install nginx +``` + +Then you'll need to get the RTMP module so Nginx can handle your media stream: + +``` +sudo add-apt-repository universe +sudo apt install libnginx-mod-rtmp +``` + +Adjust your web server's configuration so it can accept and deliver your media stream. + +``` +sudo nano /etc/nginx/nginx.conf +``` + +Scroll to the bottom of the configuration file and add the following code: + +``` +rtmp { + server { + listen 1935; + chunk_size 4096; + + application live { + live on; + record off; + } + } +} +``` + + + +Save the config. Because I'm a heretic, I use [Nano][3] for editing configuration files. In Nano, you can save your config by pressing **Ctrl+X** , **Y** , and then **Enter.** + +This is a very minimal config that will create a working streaming server. You'll add to this config later, but this is a great starting point. + +However, before you can begin your first stream, you'll need to restart Nginx with its new configuration: + +``` +sudo systemctl restart nginx +``` + +### Setting up a BSD server + +If you're of the "beastie" persuasion, getting a streaming server up and running is also devilishly easy. + +Head on over to the [FreeBSD][4] website and download the latest release. Fire up the FreeBSD installer on your computer or virtual machine and go through the initial steps and choose settings that best match your environment. Since this is a server, you'll likely want to set some static network settings. + +After the installer finishes and your system reboots, you should have a shiny new FreeBSD system. Like any other freshly installed system, you'll likely want to get everything updated (from this step forward, make sure you're logged in as root): + +``` +pkg update +pkg upgrade +``` + +I install [Nano][3] for editing configuration files: + +``` +pkg install nano +``` + +This streaming server will use the very powerful and versatile Nginx web server. You can build Nginx using the excellent ports system that FreeBSD boasts. + +First, update your ports tree: + +``` +portsnap fetch +portsnap extract +``` + +Browse to the Nginx ports directory: + +``` +cd /usr/ports/www/nginx +``` + +And begin building Nginx by running: + +``` +make install +``` + +You'll see a screen asking what modules to include in your Nginx build. For this project, you'll need to add the RTMP module. Scroll down until the RTMP module is selected and press **Space**. Then Press **Enter** to proceed with the rest of the build and installation. + +Once Nginx has finished installing, it's time to configure it for streaming purposes. + +First, add an entry into **/etc/rc.conf** to ensure the Nginx server starts when your system boots: + +``` +nano /etc/rc.conf +``` + +Add this text to the file: + +``` +nginx_enable="YES" +``` + + + +Next, create a webroot directory from where Nginx will serve its content. I call mine **stream** : + +``` +cd /usr/local/www/ +mkdir stream +chmod -R 755 stream/ +``` + +Now that you have created your stream directory, configure Nginx by editing its configuration file: + +``` +nano /usr/local/etc/nginx/nginx.conf +``` + +Load your streaming modules at the top of the file: + +``` +load_module /usr/local/libexec/nginx/ngx_stream_module.so; +load_module /usr/local/libexec/nginx/ngx_rtmp_module.so; +``` + + + +Under the **Server** section, change the webroot location to match the one you created earlier: + +``` +Location / { +root /usr/local/www/stream +} +``` + + + +And finally, add your RTMP settings so Nginx will know how to handle your media streams: + +``` +rtmp { + server { + listen 1935; + chunk_size 4096; + + application live { + live on; + record off; + } + } +} +``` + +Save the config. In Nano, you can do this by pressing **Ctrl+X** , **Y** , and then **Enter.** + +As you can see, this is a very minimal config that will create a working streaming server. Later, you'll add to this config, but this will provide you with a great starting point. + +However, before you can begin your first stream, you'll need to restart Nginx with its new config: + +``` +service nginx restart +``` + +### Set up your streaming software + +#### Broadcasting with OBS + +Now that your server is ready to accept your video streams, it's time to set up your streaming software. This tutorial uses the powerful and open source Open Broadcast Studio (OBS). + +Head over to the [OBS website][5] and find the build for your operating system and install it. Once OBS launches, you should see a first-time-run wizard that will help you configure OBS with the settings that best fit your hardware. + + + +OBS isn't capturing anything because you haven't supplied it with a source. For this tutorial, you'll just capture your desktop for the stream. Simply click the **+** button under **Source** , choose **Screen Capture** , and select which desktop you want to capture. + +Click OK, and you should see OBS mirroring your desktop. + +Now it's time to send your newly configured video stream to your server. In OBS, click **File** > **Settings**. Click on the **Stream** section, and set **Stream Type** to **Custom Streaming Server**. + +In the URL box, enter the prefix **rtmp://** followed the IP address of your streaming server followed by **/live**. For example, **rtmp://IP-ADDRESS/live**. + +Next, you'll probably want to enter a Stream key—a special identifier required to view your stream. Enter whatever key you want (and can remember) in the **Stream key** box. + + + +Click **Apply** and then **OK**. + +Now that OBS is configured to send your stream to your server, you can start your first stream. Click **Start Streaming**. + +If everything worked, you should see the button change to **Stop Streaming** and some bandwidth metrics will appear at the bottom of OBS. + + + +If you receive an error, double-check Stream Settings in OBS for misspellings. If everything looks good, there could be another issue preventing it from working. + +### Viewing your stream + +A live video isn't much good if no one is watching it, so be your first viewer! + +There are a multitude of open source media players that support RTMP, but the most well-known is probably [VLC media player][6]. + +After you install and launch VLC, open your stream by clicking on **Media** > **Open Network Stream**. Enter the path to your stream, adding the Stream Key you set up in OBS, then click **Play**. For example, **rtmp://IP-ADDRESS/live/SECRET-KEY**. + +You should now be viewing your very own live video stream! + + + +### Where to go next? + +This is a very simple setup that will get you off the ground. Here are two other features you likely will want to use. + + * **Limit access:** The next step you might want to take is to limit access to your server, as the default setup allows anyone to stream to and from the server. There are a variety of ways to set this up, such as an operating system firewall, [.htaccess file][7], or even using the [built-in access controls in the STMP module][8]. + + * **Record streams:** This simple Nginx configuration will only stream and won't save your videos, but this is easy to add. In the Nginx config, under the RTMP section, set up the recording options and the location where you want to save your videos. Make sure the path you set exists and Nginx is able to write to it. + + + + +``` +application live { + live on; + record all; + record_path /var/www/html/recordings; + record_unique on; +} +``` + +The world of live streaming is constantly evolving, and if you're interested in more advanced uses, there are lots of other great resources you can find floating around the internet. Good luck and happy streaming! + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/basic-live-video-streaming-server + +作者：[Aaron J.Prisk][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/ricepriskytreat +[b]: https://github.com/lujun9972 +[1]: https://www.ubuntu.com/download/server +[2]: https://www.ubuntu.com/download/desktop +[3]: https://www.nano-editor.org/ +[4]: https://www.freebsd.org/ +[5]: https://obsproject.com/ +[6]: https://www.videolan.org/vlc/index.html +[7]: https://httpd.apache.org/docs/current/howto/htaccess.html +[8]: https://github.com/arut/nginx-rtmp-module/wiki/Directives#access diff --git a/sources/tech/20190108 How ASLR protects Linux systems from buffer overflow attacks.md b/sources/tech/20190108 How ASLR protects Linux systems from buffer overflow attacks.md new file mode 100644 index 0000000000..41d4e47acc --- /dev/null +++ b/sources/tech/20190108 How ASLR protects Linux systems from buffer overflow attacks.md @@ -0,0 +1,133 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How ASLR protects Linux systems from buffer overflow attacks) +[#]: via: (https://www.networkworld.com/article/3331199/linux/what-does-aslr-do-for-linux.html) +[#]: author: (Sandra Henry-Stocker https://www.networkworld.com/author/Sandra-Henry_Stocker/) + +How ASLR protects Linux systems from buffer overflow attacks +====== + + + +Address Space Layout Randomization (ASLR) is a memory-protection process for operating systems that guards against buffer-overflow attacks. It helps to ensure that the memory addresses associated with running processes on systems are not predictable, thus flaws or vulnerabilities associated with these processes will be more difficult to exploit. + +ASLR is used today on Linux, Windows, and MacOS systems. It was first implemented on Linux in 2005. In 2007, the technique was deployed on Microsoft Windows and MacOS. While ASLR provides the same function on each of these operating systems, it is implemented differently on each one. + +The effectiveness of ASLR is dependent on the entirety of the address space layout remaining unknown to the attacker. In addition, only executables that are compiled as Position Independent Executable (PIE) programs will be able to claim the maximum protection from ASLR technique because all sections of the code will be loaded at random locations. PIE machine code will execute properly regardless of its absolute address. + +**[ Also see:[Invaluable tips and tricks for troubleshooting Linux][1] ]** + +### ASLR limitations + +In spite of ASLR making exploitation of system vulnerabilities more difficult, its role in protecting systems is limited. It's important to understand that ASLR: + + * Doesn't _resolve_ vulnerabilities, but makes exploiting them more of a challenge + * Doesn't track or report vulnerabilities + * Doesn't offer any protection for binaries that are not built with ASLR support + * Isn't immune to circumvention + + + +### How ASLR works + +ASLR increases the control-flow integrity of a system by making it more difficult for an attacker to execute a successful buffer-overflow attack by randomizing the offsets it uses in memory layouts. + +ASLR works considerably better on 64-bit systems, as these systems provide much greater entropy (randomization potential). + +### Is ASLR working on your Linux system? + +Either of the two commands shown below will tell you whether ASLR is enabled on your system. + +``` +$ cat /proc/sys/kernel/randomize_va_space +2 +$ sysctl -a --pattern randomize +kernel.randomize_va_space = 2 +``` + +The value (2) shown in the commands above indicates that ASLR is working in full randomization mode. The value shown will be one of the following: + +``` +0 = Disabled +1 = Conservative Randomization +2 = Full Randomization +``` + +If you disable ASLR and run the commands below, you should notice that the addresses shown in the **ldd** output below are all the same in the successive **ldd** commands. The **ldd** command works by loading the shared objects and showing where they end up in memory. + +``` +$ sudo sysctl -w kernel.randomize_va_space=0 <== disable +[sudo] password for shs: +kernel.randomize_va_space = 0 +$ ldd /bin/bash + linux-vdso.so.1 (0x00007ffff7fd1000) <== same addresses + libtinfo.so.6 => /lib/x86_64-linux-gnu/libtinfo.so.6 (0x00007ffff7c69000) + libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007ffff7c63000) + libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007ffff7a79000) + /lib64/ld-linux-x86-64.so.2 (0x00007ffff7fd3000) +$ ldd /bin/bash + linux-vdso.so.1 (0x00007ffff7fd1000) <== same addresses + libtinfo.so.6 => /lib/x86_64-linux-gnu/libtinfo.so.6 (0x00007ffff7c69000) + libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007ffff7c63000) + libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007ffff7a79000) + /lib64/ld-linux-x86-64.so.2 (0x00007ffff7fd3000) +``` + +If the value is set back to **2** to enable ASLR, you will see that the addresses will change each time you run the command. + +``` +$ sudo sysctl -w kernel.randomize_va_space=2 <== enable +[sudo] password for shs: +kernel.randomize_va_space = 2 +$ ldd /bin/bash + linux-vdso.so.1 (0x00007fff47d0e000) <== first set of addresses + libtinfo.so.6 => /lib/x86_64-linux-gnu/libtinfo.so.6 (0x00007f1cb7ce0000) + libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f1cb7cda000) + libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f1cb7af0000) + /lib64/ld-linux-x86-64.so.2 (0x00007f1cb8045000) +$ ldd /bin/bash + linux-vdso.so.1 (0x00007ffe1cbd7000) <== second set of addresses + libtinfo.so.6 => /lib/x86_64-linux-gnu/libtinfo.so.6 (0x00007fed59742000) + libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fed5973c000) + libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fed59552000) + /lib64/ld-linux-x86-64.so.2 (0x00007fed59aa7000) +``` + +### Attempting to bypass ASLR + +In spite of its advantages, attempts to bypass ASLR are not uncommon and seem to fall into several categories: + + * Using address leaks + * Gaining access to data relative to particular addresses + * Exploiting implementation weaknesses that allow attackers to guess addresses when entropy is low or when the ASLR implementation is faulty + * Using side channels of hardware operation + + + +### Wrap-up + +ASLR is of great value, especially when run on 64 bit systems and implemented properly. While not immune from circumvention attempts, it does make exploitation of system vulnerabilities considerably more difficult. Here is a reference that can provide a lot more detail [on the Effectiveness of Full-ASLR on 64-bit Linux][2], and here is a paper on one circumvention effort to [bypass ASLR][3] using branch predictors. + +Join the Network World communities on [Facebook][4] and [LinkedIn][5] to comment on topics that are top of mind. + +-------------------------------------------------------------------------------- + +via: https://www.networkworld.com/article/3331199/linux/what-does-aslr-do-for-linux.html + +作者：[Sandra Henry-Stocker][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.networkworld.com/author/Sandra-Henry_Stocker/ +[b]: https://github.com/lujun9972 +[1]: https://www.networkworld.com/article/3242170/linux/invaluable-tips-and-tricks-for-troubleshooting-linux.html +[2]: https://cybersecurity.upv.es/attacks/offset2lib/offset2lib-paper.pdf +[3]: http://www.cs.ucr.edu/~nael/pubs/micro16.pdf +[4]: https://www.facebook.com/NetworkWorld/ +[5]: https://www.linkedin.com/company/network-world diff --git a/sources/tech/20190108 How To Understand And Identify File types in Linux.md b/sources/tech/20190108 How To Understand And Identify File types in Linux.md new file mode 100644 index 0000000000..c1c4ca4c0a --- /dev/null +++ b/sources/tech/20190108 How To Understand And Identify File types in Linux.md @@ -0,0 +1,359 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How To Understand And Identify File types in Linux) +[#]: via: (https://www.2daygeek.com/how-to-understand-and-identify-file-types-in-linux/) +[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/) + +How To Understand And Identify File types in Linux +====== + +We all are knows, that everything is a file in Linux which includes Hard Disk, Graphics Card, etc. + +When you are navigating the Linux filesystem most of the files are fall under regular files and directories. + +But it has other file types as well for different purpose which fall in five categories. + +So, it’s very important to understand the file types in Linux that helps you in many ways. + +If you can’t believe this, you just gone through the complete article then you come to know how important is. + +If you don’t understand the file types you can’t make any changes on that without fear. + +If you made the changes wrongly that damage your system very badly so be careful when you are doing that. + +Files are very important in Linux because all the devices and daemon’s were stored as a file in Linux system. + +### How Many Types of File is Available in Linux? + +As per my knowledge, totally 7 types of files are available in Linux with 3 Major categories. The details are below. + + * Regular File + * Directory File + * Special Files (This category having five type of files) + * Link File + * Character Device File + * Socket File + * Named Pipe File + * Block File + + + +Refer the below table for better understanding of file types in Linux. +| Symbol | Meaning | +| – | Regular File. It starts with underscore “_”. | +| d | Directory File. It starts with English alphabet letter “d”. | +| l | Link File. It starts with English alphabet letter “l”. | +| c | Character Device File. It starts with English alphabet letter “c”. | +| s | Socket File. It starts with English alphabet letter “s”. | +| p | Named Pipe File. It starts with English alphabet letter “p”. | +| b | Block File. It starts with English alphabet letter “b”. | + +### Method-1: Manual Way to Identify File types in Linux + +If you are having good knowledge in Linux then you can easily identify the files type with help of above table. + +#### How to view the Regular files in Linux? + +Use the below command to view the Regular files in Linux. Regular files are available everywhere in Linux filesystem. +The Regular files color is `WHITE` + +``` +# ls -la | grep ^- +-rw-------. 1 mageshm mageshm 1394 Jan 18 15:59 .bash_history +-rw-r--r--. 1 mageshm mageshm 18 May 11 2012 .bash_logout +-rw-r--r--. 1 mageshm mageshm 176 May 11 2012 .bash_profile +-rw-r--r--. 1 mageshm mageshm 124 May 11 2012 .bashrc +-rw-r--r--. 1 root root 26 Dec 27 17:55 liks +-rw-r--r--. 1 root root 104857600 Jan 31 2006 test100.dat +-rw-r--r--. 1 root root 104874307 Dec 30 2012 test100.zip +-rw-r--r--. 1 root root 11536384 Dec 30 2012 test10.zip +-rw-r--r--. 1 root root 61 Dec 27 19:05 test2-bzip2.txt +-rw-r--r--. 1 root root 61 Dec 31 14:24 test3-bzip2.txt +-rw-r--r--. 1 root root 60 Dec 27 19:01 test-bzip2.txt +``` + +#### How to view the Directory files in Linux? + +Use the below command to view the Directory files in Linux. Directory files are available everywhere in Linux filesystem. The Directory files colour is `BLUE` + +``` +# ls -la | grep ^d +drwxr-xr-x. 3 mageshm mageshm 4096 Dec 31 14:24 links/ +drwxrwxr-x. 2 mageshm mageshm 4096 Nov 16 15:44 perl5/ +drwxr-xr-x. 2 mageshm mageshm 4096 Nov 16 15:37 public_ftp/ +drwxr-xr-x. 3 mageshm mageshm 4096 Nov 16 15:37 public_html/ +``` + +#### How to view the Link files in Linux? + +Use the below command to view the Link files in Linux. Link files are available everywhere in Linux filesystem. +Two type of link files are available, it’s Soft link and Hard link. The Link files color is `LIGHT TURQUOISE` + +``` +# ls -la | grep ^l +lrwxrwxrwx. 1 root root 31 Dec 7 15:11 s-link-file -> /links/soft-link/test-soft-link +lrwxrwxrwx. 1 root root 38 Dec 7 15:12 s-link-folder -> /links/soft-link/test-soft-link-folder +``` + +#### How to view the Character Device files in Linux? + +Use the below command to view the Character Device files in Linux. Character Device files are available only in specific location. + +It’s available under `/dev` directory. The Character Device files color is `YELLOW` + +``` +# ls -la | grep ^c +crw-------. 1 root root 5, 1 Jan 28 14:05 console +crw-rw----. 1 root root 10, 61 Jan 28 14:05 cpu_dma_latency +crw-rw----. 1 root root 10, 62 Jan 28 14:05 crash +crw-rw----. 1 root root 29, 0 Jan 28 14:05 fb0 +crw-rw-rw-. 1 root root 1, 7 Jan 28 14:05 full +crw-rw-rw-. 1 root root 10, 229 Jan 28 14:05 fuse +``` + +#### How to view the Block files in Linux? + +Use the below command to view the Block files in Linux. The Block files are available only in specific location. +It’s available under `/dev` directory. The Block files color is `YELLOW` + +``` +# ls -la | grep ^b +brw-rw----. 1 root disk 7, 0 Jan 28 14:05 loop0 +brw-rw----. 1 root disk 7, 1 Jan 28 14:05 loop1 +brw-rw----. 1 root disk 7, 2 Jan 28 14:05 loop2 +brw-rw----. 1 root disk 7, 3 Jan 28 14:05 loop3 +brw-rw----. 1 root disk 7, 4 Jan 28 14:05 loop4 +``` + +#### How to view the Socket files in Linux? + +Use the below command to view the Socket files in Linux. The Socket files are available only in specific location. +The Socket files color is `PINK` + +``` +# ls -la | grep ^s +srw-rw-rw- 1 root root 0 Jan 5 16:36 system_bus_socket +``` + +#### How to view the Named Pipe files in Linux? + +Use the below command to view the Named Pipe files in Linux. The Named Pipe files are available only in specific location. The Named Pipe files color is `YELLOW` + +``` +# ls -la | grep ^p +prw-------. 1 root root 0 Jan 28 14:06 replication-notify-fifo| +prw-------. 1 root root 0 Jan 28 14:06 stats-mail| +``` + +### Method-2: How to Identify File types in Linux Using file Command? + +The file command allow us to determine various file types in Linux. There are three sets of tests, performed in this order: filesystem tests, magic tests, and language tests to identify file types. + +#### How to view the Regular files in Linux Using file Command? + +Simple enter the file command on your terminal and followed by Regular file. The file command will read the given file contents and display exactly what kind of file it is. + +That’s why we are seeing different results for each Regular files. See the below various results for Regular files. + +``` +# file 2daygeek_access.log +2daygeek_access.log: ASCII text, with very long lines + +# file powertop.html +powertop.html: HTML document, ASCII text, with very long lines + +# file 2g-test +2g-test: JSON data + +# file powertop.txt +powertop.txt: HTML document, UTF-8 Unicode text, with very long lines + +# file 2g-test-05-01-2019.tar.gz +2g-test-05-01-2019.tar.gz: gzip compressed data, last modified: Sat Jan 5 18:22:20 2019, from Unix, original size 450560 +``` + +#### How to view the Directory files in Linux Using file Command? + +Simple enter the file command on your terminal and followed by Directory file. See the results below. + +``` +# file Pictures/ +Pictures/: directory +``` + +#### How to view the Link files in Linux Using file Command? + +Simple enter the file command on your terminal and followed by Link file. See the results below. + +``` +# file log +log: symbolic link to /run/systemd/journal/dev-log +``` + +#### How to view the Character Device files in Linux Using file Command? + +Simple enter the file command on your terminal and followed by Character Device file. See the results below. + +``` +# file vcsu +vcsu: character special (7/64) +``` + +#### How to view the Block files in Linux Using file Command? + +Simple enter the file command on your terminal and followed by Block file. See the results below. + +``` +# file sda1 +sda1: block special (8/1) +``` + +#### How to view the Socket files in Linux Using file Command? + +Simple enter the file command on your terminal and followed by Socket file. See the results below. + +``` +# file system_bus_socket +system_bus_socket: socket +``` + +#### How to view the Named Pipe files in Linux Using file Command? + +Simple enter the file command on your terminal and followed by Named Pipe file. See the results below. + +``` +# file pipe-test +pipe-test: fifo (named pipe) +``` + +### Method-3: How to Identify File types in Linux Using stat Command? + +The stat command allow us to check file types or file system status. This utility giving more information than file command. It shows lot of information about the given file such as Size, Block Size, IO Block Size, Inode Value, Links, File permission, UID, GID, File Access, Modify and Change time details. + +#### How to view the Regular files in Linux Using stat Command? + +Simple enter the stat command on your terminal and followed by Regular file. + +``` +# stat 2daygeek_access.log + File: 2daygeek_access.log + Size: 14406929 Blocks: 28144 IO Block: 4096 regular file +Device: 10301h/66305d Inode: 1727555 Links: 1 +Access: (0644/-rw-r--r--) Uid: ( 1000/ daygeek) Gid: ( 1000/ daygeek) +Access: 2019-01-03 14:05:26.430328867 +0530 +Modify: 2019-01-03 14:05:26.460328868 +0530 +Change: 2019-01-03 14:05:26.460328868 +0530 + Birth: - +``` + +#### How to view the Directory files in Linux Using stat Command? + +Simple enter the stat command on your terminal and followed by Directory file. See the results below. + +``` +# stat Pictures/ + File: Pictures/ + Size: 4096 Blocks: 8 IO Block: 4096 directory +Device: 10301h/66305d Inode: 1703982 Links: 3 +Access: (0755/drwxr-xr-x) Uid: ( 1000/ daygeek) Gid: ( 1000/ daygeek) +Access: 2018-11-24 03:22:11.090000828 +0530 +Modify: 2019-01-05 18:27:01.546958817 +0530 +Change: 2019-01-05 18:27:01.546958817 +0530 + Birth: - +``` + +#### How to view the Link files in Linux Using stat Command? + +Simple enter the stat command on your terminal and followed by Link file. See the results below. + +``` +# stat /dev/log + File: /dev/log -> /run/systemd/journal/dev-log + Size: 28 Blocks: 0 IO Block: 4096 symbolic link +Device: 6h/6d Inode: 278 Links: 1 +Access: (0777/lrwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root) +Access: 2019-01-05 16:36:31.033333447 +0530 +Modify: 2019-01-05 16:36:30.766666768 +0530 +Change: 2019-01-05 16:36:30.766666768 +0530 + Birth: - +``` + +#### How to view the Character Device files in Linux Using stat Command? + +Simple enter the stat command on your terminal and followed by Character Device file. See the results below. + +``` +# stat /dev/vcsu + File: /dev/vcsu + Size: 0 Blocks: 0 IO Block: 4096 character special file +Device: 6h/6d Inode: 16 Links: 1 Device type: 7,40 +Access: (0660/crw-rw----) Uid: ( 0/ root) Gid: ( 5/ tty) +Access: 2019-01-05 16:36:31.056666781 +0530 +Modify: 2019-01-05 16:36:31.056666781 +0530 +Change: 2019-01-05 16:36:31.056666781 +0530 + Birth: - +``` + +#### How to view the Block files in Linux Using stat Command? + +Simple enter the stat command on your terminal and followed by Block file. See the results below. + +``` +# stat /dev/sda1 + File: /dev/sda1 + Size: 0 Blocks: 0 IO Block: 4096 block special file +Device: 6h/6d Inode: 250 Links: 1 Device type: 8,1 +Access: (0660/brw-rw----) Uid: ( 0/ root) Gid: ( 994/ disk) +Access: 2019-01-05 16:36:31.596666806 +0530 +Modify: 2019-01-05 16:36:31.596666806 +0530 +Change: 2019-01-05 16:36:31.596666806 +0530 + Birth: - +``` + +#### How to view the Socket files in Linux Using stat Command? + +Simple enter the stat command on your terminal and followed by Socket file. See the results below. + +``` +# stat /var/run/dbus/system_bus_socket + File: /var/run/dbus/system_bus_socket + Size: 0 Blocks: 0 IO Block: 4096 socket +Device: 15h/21d Inode: 576 Links: 1 +Access: (0666/srw-rw-rw-) Uid: ( 0/ root) Gid: ( 0/ root) +Access: 2019-01-05 16:36:31.823333482 +0530 +Modify: 2019-01-05 16:36:31.810000149 +0530 +Change: 2019-01-05 16:36:31.810000149 +0530 + Birth: - +``` + +#### How to view the Named Pipe files in Linux Using stat Command? + +Simple enter the stat command on your terminal and followed by Named Pipe file. See the results below. + +``` +# stat pipe-test + File: pipe-test + Size: 0 Blocks: 0 IO Block: 4096 fifo +Device: 10301h/66305d Inode: 1705583 Links: 1 +Access: (0644/prw-r--r--) Uid: ( 1000/ daygeek) Gid: ( 1000/ daygeek) +Access: 2019-01-06 02:00:03.040394731 +0530 +Modify: 2019-01-06 02:00:03.040394731 +0530 +Change: 2019-01-06 02:00:03.040394731 +0530 + Birth: - +``` +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/how-to-understand-and-identify-file-types-in-linux/ + +作者：[Magesh Maruthamuthu][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.2daygeek.com/author/magesh/ +[b]: https://github.com/lujun9972 diff --git a/sources/tech/20190109 Automating deployment strategies with Ansible.md b/sources/tech/20190109 Automating deployment strategies with Ansible.md new file mode 100644 index 0000000000..175244e760 --- /dev/null +++ b/sources/tech/20190109 Automating deployment strategies with Ansible.md @@ -0,0 +1,152 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Automating deployment strategies with Ansible) +[#]: via: (https://opensource.com/article/19/1/automating-deployment-strategies-ansible) +[#]: author: (Jario da Silva Junior https://opensource.com/users/jairojunior) + +Automating deployment strategies with Ansible +====== +Use automation to eliminate time sinkholes due to repetitive tasks and unplanned work. + + +When you examine your technology stack from the bottom layer to the top—hardware, operating system (OS), middleware, and application—with their respective configurations, it's clear that changes are far more frequent as you go up in the stack. Your hardware will hardly change, your OS has a long lifecycle, and your middleware will keep up with the application's needs, but even if your release cycle is long (weeks or months), your applications will be the most volatile. + + + +In [The Practice of System and Network Administration][1], the authors categorize the biggest "time sinkholes" in IT as manual/non-standard provisioning of OSes and application deployments. These time sinkholes will consume you with repetitive tasks or unplanned work. + +How so? Let's say you provision a new server without Network Time Protocol (NTP) properly configured, and a small percentage of your requests—in a cluster of dozens of servers—start to behave strangely because an application uses some sort of scheduler that relies on correct time. When you look at it like this, it is an easy problem to fix, but how long it would it take your team figure it out? Incidents or unplanned work consume a lot of your time and, even worse, your greatest talents. Should you really be wasting time investigating production systems like this? Wouldn't it be better to set this server aside and automatically provision a new one from scratch? + +What about manual deployment? Imagine 20 binaries deployed across a farm or nodes with their respective configuration files? How error-prone is this? Inevitably, it will eventually end up in unplanned work. + +The [State of DevOps Report 2018][2] introduces the stages of DevOps adoption, and it's no surprise that Stage 0 includes deployment automation and reuse of deployment patterns, while Stage 1 and 2 focus on standardization of your infrastructure stack to reduce inconsistencies across your environment. + +Note that, more than once, I have seen an ops team using this "standardization" as an excuse to limit a development team's ability to deliver, forcing them to use a hammer on something that is definitely not a nail. Don't do it; the price is extremely high. + +The lesson to be learned here is that lack of automation not only increases your lead time but also the rate of problems in your process and the amount of unplanned work you face. If you've read [The Phoenix Project][3], you know this is the root of all evil in any value stream, and if you don't get rid of it, it will eventually kill your business. + +When trying to fill the biggest time sinkholes, why not start with automating operating system installation? We could, but the results would take longer to appear since new virtual machines are not created as frequently as applications are deployed. In other words, this may not free up the time we need to power our initiative, so it could die prematurely. + +Still not convinced? Smaller and more frequent releases are also extremely positive from the development side. Let's explain a little further… + +### Deploy ≠ Release + +The first thing to understand is that, although they're used interchangeably, deployment and release do **NOT** mean the same thing. Release refers to providing the user a new version, while deployment is the technical process of deploying the new version. Let's focus on the technical process of deployment. + +### Tasks, groups, and Ansible + +We need to understand the deployment process from the beginning to the end, including everything in the middle—the tasks, which servers are involved in the process, and which steps are executed—to avoid falling into the pitfalls described by Mattias Geniar in [Automating the unknown][4]. + +#### Tasks + +The steps commonly executed in a regular deployment process include: + + * Deploy application(s)/database(s) or database(s) change(s) + * Stop/start services and monitoring + * Add/remove the server from our load balancers + * Verify application state—is it ready to serve requests? + * Manual approval—is it necessary? + + + +For some people, automating the deployment process but leaving a manual approval step is like riding a bike with training wheels. As someone once told me: "It's better to ride with training wheels than not ride at all." + +What if a tool doesn't include an API or a command-line interface (CLI) to enable task automation? Well, maybe it's time to think about changing tools. There are many open source application servers, databases, monitoring systems, and load balancers that are easily automated—thanks in large part to the [Unix way][5]. When adopting a new technology, eliminate options that are not automated and use your creativity to support your legacy technologies. For example, I've seen people versioning network appliance configuration files and updating them using FTP. + +And guess what? It's a wonderful time to adopt open source tools. The recent [Accelerate: State of DevOps][6] report found that open source technologies are in predominant use in high-performance organizations. The logic is pretty simple: open source projects function in a "Darwinist" model, where those that do not adapt and evolve will die for lack of a user base or contributions. Feedback is paramount to software evolution. + +#### Groups + +To identify groups of servers to target for automation, think about the most tasks you want to automate, such as those that: + + * Deploy application(s)/database(s) or database change(s) + * Stop/start services and monitoring + * Add/remove server(s) from load balancer(s) + * Verify application state—is it ready to serve requests? + + + +#### The playbook + +A high-level deployment process could be: + + 1. Stop monitoring (to avoid false-positives) + 2. Remove server from the load balancer (to prevent the user from receiving an error code) + 3. Stop the service (to enable a graceful shutdown) + 4. Deploy the new version of the application + 5. Wait for the application to be ready to receive new requests + 6. Execute steps 3, 2, and 1. + 7. Do the same for the next N servers. + + + +Having documentation of your process is nice, but having an executable documenting your deployment is better! Here's what steps 1–5 would look like in Ansible for a fully open source stack: + +``` +- name: Disable alerts + nagios: + action: disable_alerts + host: "{{ inventory_hostname }}" + services: webserver + delegate_to: "{{ item }}" + loop: "{{ groups.monitoring }}" + +- name: Disable servers in the LB + haproxy: + host: "{{ inventory_hostname }}" + state: disabled + backend: app + delegate_to: "{{ item }}" + loop: " {{ groups.lbserver }}" + +- name: Stop the service + service: name=httpd state=stopped + +- name: Deploy a new version + unarchive: src=app.tar.gz dest=/var/www/app + +- name: Verify application state + uri: + url: "http://{{ inventory_hostname }}/app/healthz" + status_code: 200 + retries: 5 +``` + +### Why Ansible? + +There are other alternatives for application deployment, but the things that make Ansible an excellent choice include: + + * Multi-tier orchestration (i.e., **delegate_to** ) allowing you to orderly target different groups of servers: monitoring, load balancer, application server, database, etc. + * Rolling upgrade (i.e., serial) to control how changes are made (e.g., 1 by 1, N by N, X% at a time, etc.) + * Error control, **max_fail_percentage** and **any_errors_fatal** , is my process all-in or will it tolerate fails? + * A vast library of modules for: + * Monitoring (e.g., Nagios, Zabbix, etc.) + * Load balancers (e.g., HAProxy, F5, Netscaler, Cisco, etc.) + * Services (e.g., service, command, file) + * Deployment (e.g., copy, unarchive) + * Programmatic verifications (e.g., command, Uniform Resource Identifier) + + + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/automating-deployment-strategies-ansible + +作者：[Jario da Silva Junior][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/jairojunior +[b]: https://github.com/lujun9972 +[1]: https://www.amazon.com/Practice-System-Network-Administration-Enterprise/dp/0321919165/ref=dp_ob_title_bk +[2]: https://puppet.com/resources/whitepaper/state-of-devops-report +[3]: https://www.amazon.com/Phoenix-Project-DevOps-Helping-Business/dp/0988262592 +[4]: https://ma.ttias.be/automating-unknown/ +[5]: https://en.wikipedia.org/wiki/Unix_philosophy +[6]: https://cloudplatformonline.com/2018-state-of-devops.html diff --git a/sources/tech/20190109 GoAccess - A Real-Time Web Server Log Analyzer And Interactive Viewer.md b/sources/tech/20190109 GoAccess - A Real-Time Web Server Log Analyzer And Interactive Viewer.md new file mode 100644 index 0000000000..3bad5ba969 --- /dev/null +++ b/sources/tech/20190109 GoAccess - A Real-Time Web Server Log Analyzer And Interactive Viewer.md @@ -0,0 +1,187 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (GoAccess – A Real-Time Web Server Log Analyzer And Interactive Viewer) +[#]: via: (https://www.2daygeek.com/goaccess-a-real-time-web-server-log-analyzer-and-interactive-viewer/) +[#]: author: (Vinoth Kumar https://www.2daygeek.com/author/vinoth/) + +GoAccess – A Real-Time Web Server Log Analyzer And Interactive Viewer +====== + +Analyzing a log file is a big headache for Linux administrators as it’s capturing a lot of things. + +Most of the newbies and L1 administrators doesn’t know how to analyze this. + +If you have good knowledge to analyze a logs then you will be a legend for NIX system. + +There are many tools available in Linux to analyze the logs easily. + +GoAccess is one of the tool which allow users to analyze web server logs easily. + +We will be going to discuss in details about GoAccess tool in this article. + +### What is GoAccess? + +GoAccess is a real-time web log analyzer and interactive viewer that runs in a terminal in *nix systems or through your browser. + +GoAccess has minimal requirements, it’s written in C and requires only ncurses. + +It will support Apache, Nginx and Lighttpd logs. It provides fast and valuable HTTP statistics for system administrators that require a visual server report on the fly. + +GoAccess parses the specified web log file and outputs the data to the X terminal and browser. + +GoAccess was designed to be a fast, terminal-based log analyzer. Its core idea is to quickly analyze and view web server statistics in real time without needing to use your browser. + +Terminal output is the default output, it has the capability to generate a complete, self-contained, real-time HTML report, as well as a JSON, and CSV report. + +GoAccess allows any custom log format and the following (Combined Log Format (XLF/ELF) Apache | Nginx & Common Log Format (CLF) Apache) predefined log format options are included, but not limited to. + +### GoAccess Features + + * **`Completely Real Time:`** All the metrics are updated every 200 ms on the terminal and every second on the HTML output. + * **`Track Application Response Time:`** Track the time taken to serve the request. Extremely useful if you want to track pages that are slowing down your site. + * **`Visitors:`** Determine the amount of hits, visitors, bandwidth, and metrics for slowest running requests by the hour, or date. + * **`Metrics per Virtual Host:`** Have multiple Virtual Hosts (Server Blocks)? It features a panel that displays which virtual host is consuming most of the web server resources. + + + +### How to Install GoAccess? + +I would advise users to install GoAccess from distribution official repository with help of Package Manager. It is available in most of the distributions official repository. + +As we know, we will be getting bit outdated package for standard release distribution and rolling release distributions always include latest package. + +If you are running the OS with standard release distributions, i would suggest you to check the alternative options such as PPA or Official GoAccess maintainer repository, etc, to get a latest package. + +For **`Debian/Ubuntu`** systems, use **[APT-GET Command][1]** or **[APT Command][2]** to install GoAccess on your systems. + +``` +# apt install goaccess +``` + +To get a latest GoAccess package, use the below GoAccess official repository. + +``` +$ echo "deb https://deb.goaccess.io/ $(lsb_release -cs) main" | sudo tee -a /etc/apt/sources.list.d/goaccess.list +$ wget -O - https://deb.goaccess.io/gnugpg.key | sudo apt-key add - +$ sudo apt-get update +$ sudo apt-get install goaccess +``` + +For **`RHEL/CentOS`** systems, use **[YUM Package Manager][3]** to install GoAccess on your systems. + +``` +# yum install goaccess +``` + +For **`Fedora`** system, use **[DNF Package Manager][4]** to install GoAccess on your system. + +``` +# dnf install goaccess +``` + +For **`ArchLinux/Manjaro`** based systems, use **[Pacman Package Manager][5]** to install GoAccess on your systems. + +``` +# pacman -S goaccess +``` + +For **`openSUSE Leap`** system, use **[Zypper Package Manager][6]** to install GoAccess on your system. + +``` +# zypper install goaccess + +# zypper ar -f obs://server:http + +# zypper ref && zypper in goaccess +``` + +### How to Use GoAccess? + +After successful installation of GoAccess. Just enter the goaccess command and followed by the web server log location to view it. + +``` +# goaccess [options] /path/to/Web Server/access.log + +# goaccess /var/log/apache/2daygeek_access.log +``` + +When you execute the above command, it will ask you to select the **Log Format Configuration**. +![][8] + +I had tested this with Apache access log. The Apache log is splitted in fifteen section. The details are below. The main section shows the summary about the fifteen section. + +The below screenshots included four sessions such as Unique Visitors, Requested files, Static Requests, Not found URLs. +![][9] + +The below screenshots included four sessions such as Visitor Hostnames and IPs, Operating Systems, Browsers, Time Distribution. +![][10] + +The below screenshots included four sessions such as Referrers URLs, Referring Sites, Google’s search engine results, HTTP status codes. +![][11] + +If you would like to generate a html report, use the following format. + +Initially i got an error when i was trying to generate the html report. + +``` +# goaccess 2daygeek_access.log -a > report.html + +GoAccess - version 1.3 - Nov 23 2018 11:28:19 +Config file: No config file used + +Fatal error has occurred +Error occurred at: src/parser.c - parse_log - 2764 +No time format was found on your conf file.Parsing... [0] [0/s] +``` + +It says “No time format was found on your conf file”. To overcome this issue, add the “COMBINED” log format option on it. + +``` +# goaccess -f 2daygeek_access.log --log-format=COMBINED -o 2daygeek.html +Parsing...[0,165] [50,165/s] +``` + +![][12] + +GoAccess allows you to access and analyze the real-time log filtering and parsing. + +``` +# tail -f /var/log/apache/2daygeek_access.log | goaccess - +``` + +For more details navigate to man or help page. + +``` +# man goaccess +or +# goaccess --help +``` + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/goaccess-a-real-time-web-server-log-analyzer-and-interactive-viewer/ + +作者：[Vinoth Kumar][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.2daygeek.com/author/vinoth/ +[b]: https://github.com/lujun9972 +[1]: https://www.2daygeek.com/apt-get-apt-cache-command-examples-manage-packages-debian-ubuntu-systems/ +[2]: https://www.2daygeek.com/apt-command-examples-manage-packages-debian-ubuntu-systems/ +[3]: https://www.2daygeek.com/yum-command-examples-manage-packages-rhel-centos-systems/ +[4]: https://www.2daygeek.com/dnf-command-examples-manage-packages-fedora-system/ +[5]: https://www.2daygeek.com/pacman-command-examples-manage-packages-arch-linux-system/ +[6]: https://www.2daygeek.com/zypper-command-examples-manage-packages-opensuse-system/ +[7]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[8]: https://www.2daygeek.com/wp-content/uploads/2019/01/goaccess-a-real-time-web-server-log-analyzer-and-interactive-viewer-1.png +[9]: https://www.2daygeek.com/wp-content/uploads/2019/01/goaccess-a-real-time-web-server-log-analyzer-and-interactive-viewer-2.png +[10]: https://www.2daygeek.com/wp-content/uploads/2019/01/goaccess-a-real-time-web-server-log-analyzer-and-interactive-viewer-3.png +[11]: https://www.2daygeek.com/wp-content/uploads/2019/01/goaccess-a-real-time-web-server-log-analyzer-and-interactive-viewer-4.png +[12]: https://www.2daygeek.com/wp-content/uploads/2019/01/goaccess-a-real-time-web-server-log-analyzer-and-interactive-viewer-5.png diff --git a/sources/tech/20190110 5 useful Vim plugins for developers.md b/sources/tech/20190110 5 useful Vim plugins for developers.md new file mode 100644 index 0000000000..2b5b9421d4 --- /dev/null +++ b/sources/tech/20190110 5 useful Vim plugins for developers.md @@ -0,0 +1,369 @@ +[#]: collector: (lujun9972) +[#]: translator: (pityonline) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (5 useful Vim plugins for developers) +[#]: via: (https://opensource.com/article/19/1/vim-plugins-developers) +[#]: author: (Ricardo Gerardi https://opensource.com/users/rgerardi) + +5 useful Vim plugins for developers +====== +Expand Vim's capabilities and improve your workflow with these five plugins for writing code. + + +I have used [Vim][1] as a text editor for over 20 years, but about two years ago I decided to make it my primary text editor. I use Vim to write code, configuration files, blog articles, and pretty much everything I can do in plaintext. Vim has many great features and, once you get used to it, you become very productive. + +I tend to use Vim's robust native capabilities for most of what I do, but there are a number of plugins developed by the open source community that extend Vim's capabilities, improve your workflow, and make you even more productive. + +Following are five plugins that are useful when using Vim to write code in any programming language. + +### 1. Auto Pairs + +The [Auto Pairs][2] plugin helps insert and delete pairs of characters, such as brackets, parentheses, or quotation marks. This is very useful for writing code, since most programming languages use pairs of characters in their syntax—such as parentheses for function calls or quotation marks for string definitions. + +In its most basic functionality, Auto Pairs inserts the corresponding closing character when you type an opening character. For example, if you enter a bracket **[** , Auto-Pairs automatically inserts the closing bracket **]**. Conversely, if you use the Backspace key to delete the opening bracket, Auto Pairs deletes the corresponding closing bracket. + +If you have automatic indentation on, Auto Pairs inserts the paired character in the proper indented position when you press Return/Enter, saving you from finding the correct position and typing the required spaces or tabs. + +Consider this Go code block for instance: + +``` +package main + +import "fmt" + +func main() { + x := true + items := []string{"tv", "pc", "tablet"} + + if x { + for _, i := range items + } +} +``` + +Inserting an opening curly brace **{** after **items** and pressing Return/Enter produces this result: + +``` +package main + +import "fmt" + +func main() { + x := true + items := []string{"tv", "pc", "tablet"} + + if x { + for _, i := range items { + | (cursor here) + } + } +} +``` + +Auto Pairs offers many other options (which you can read about on [GitHub][3]), but even these basic features will save time. + +### 2. NERD Commenter + +The [NERD Commenter][4] plugin adds code-commenting functions to Vim, similar to the ones found in an integrated development environment (IDE). With this plugin installed, you can select one or several lines of code and change them to comments with the press of a button. + +NERD Commenter integrates with the standard Vim [filetype][5] plugin, so it understands several programming languages and uses the appropriate commenting characters for single or multi-line comments. + +The easiest way to get started is by pressing **Leader+Space** to toggle the current line between commented and uncommented. The standard Vim Leader key is the **\** character. + +In Visual mode, you can select multiple lines and toggle their status at the same time. NERD Commenter also understands counts, so you can provide a count n followed by the command to change n lines together. + +Other useful features are the "Sexy Comment," triggered by **Leader+cs** , which creates a fancy comment block using the multi-line comment character. For example, consider this block of code: + +``` +package main + +import "fmt" + +func main() { + x := true + items := []string{"tv", "pc", "tablet"} + + if x { + for _, i := range items { + fmt.Println(i) + } + } +} +``` + +Selecting all the lines in **function main** and pressing **Leader+cs** results in the following comment block: + +``` +package main + +import "fmt" + +func main() { +/* + * x := true + * items := []string{"tv", "pc", "tablet"} + * + * if x { + * for _, i := range items { + * fmt.Println(i) + * } + * } + */ +} +``` + +Since all the lines are commented in one block, you can uncomment the entire block by toggling any of the lines of the block with **Leader+Space**. + +NERD Commenter is a must-have for any developer using Vim to write code. + +### 3. VIM Surround + +The [Vim Surround][6] plugin helps you "surround" existing text with pairs of characters (such as parentheses or quotation marks) or tags (such as HTML or XML tags). It's similar to Auto Pairs but, instead of working while you're inserting text, it's more useful when you're editing text. + +For example, if you have the following sentence: + +``` +"Vim plugins are awesome !" +``` + +You can remove the quotation marks around the sentence by pressing the combination **ds"** while your cursor is anywhere between the quotation marks: + +``` +Vim plugins are awesome ! +``` + +You can also change the double quotation marks to single quotation marks with the command **cs"'** : + +``` +'Vim plugins are awesome !' +``` + +Or replace them with brackets by pressing **cs'[** + +``` +[ Vim plugins are awesome ! ] +``` + +While it's a great help for text objects, this plugin really shines when working with HTML or XML tags. Consider the following HTML line: + +``` ++ +mysql +mysql-arch.example.com +3306 +kodi +kodi ++ +true +true ++ + +1 +322122547 +20 +Vim plugins are awesome !
+``` + +You can emphasize the word "awesome" by pressing the combination **ysiw ** while the cursor is anywhere on that word: + +``` +Vim plugins are awesome !
+``` + +Notice that the plugin is smart enough to use the proper closing tag **< /em>**. + +Vim Surround can also indent text and add tags in their own lines using **ySS**. For example, if you have: + +``` +Vim plugins are awesome !
+``` + +Add a **div** tag with this combination: **ySS**, and notice that the paragraph line is indented automatically. + +``` +++``` + +Vim Surround has many other options. Give it a try—and consult [GitHub][7] for additional information. + +### 4\. Vim Gitgutter + +The [Vim Gitgutter][8] plugin is useful for anyone using Git for version control. It shows the output of **Git diff** as symbols in the "gutter"—the sign column where Vim presents additional information, such as line numbers. For example, consider the following as the committed version in Git: + +``` + 1 package main + 2 + 3 import "fmt" + 4 + 5 func main() { + 6 x := true + 7 items := []string{"tv", "pc", "tablet"} + 8 + 9 if x { + 10 for _, i := range items { + 11 fmt.Println(i) + 12 } + 13 } + 14 } +``` + +After making some changes, Vim Gitgutter displays the following symbols in the gutter: + +``` + 1 package main + 2 + 3 import "fmt" + 4 +_ 5 func main() { + 6 items := []string{"tv", "pc", "tablet"} + 7 +~ 8 if len(items) > 0 { + 9 for _, i := range items { + 10 fmt.Println(i) ++ 11 fmt.Println("------") + 12 } + 13 } + 14 } +``` + +The **-** symbol shows that a line was deleted between lines 5 and 6. The **~** symbol shows that line 8 was modified, and the symbol **+** shows that line 11 was added. + +In addition, Vim Gitgutter allows you to navigate between "hunks"—individual changes made in the file—with **[c** and **]c** , or even stage individual hunks for commit by pressing **Leader+hs**. + +This plugin gives you immediate visual feedback of changes, and it's a great addition to your toolbox if you use Git. + +### 5\. VIM Fugitive + +[Vim Fugitive][9] is another great plugin for anyone incorporating Git into the Vim workflow. It's a Git wrapper that allows you to execute Git commands directly from Vim and integrates with Vim's interface. This plugin has many features—check its [GitHub][10] page for more information. + +Here's a basic Git workflow example using Vim Fugitive. Considering the changes we've made to the Go code block on section 4, you can use **git blame** by typing the command **:Gblame** : + +``` +e9949066 (Ricardo Gerardi 2018-12-05 18:17:19 -0500)│ 1 package main +e9949066 (Ricardo Gerardi 2018-12-05 18:17:19 -0500)│ 2 +e9949066 (Ricardo Gerardi 2018-12-05 18:17:19 -0500)│ 3 import "fmt" +e9949066 (Ricardo Gerardi 2018-12-05 18:17:19 -0500)│ 4 +e9949066 (Ricardo Gerardi 2018-12-05 18:17:19 -0500)│_ 5 func main() { +e9949066 (Ricardo Gerardi 2018-12-05 18:17:19 -0500)│ 6 items := []string{"tv", "pc", "tablet"} +e9949066 (Ricardo Gerardi 2018-12-05 18:17:19 -0500)│ 7 +00000000 (Not Committed Yet 2018-12-05 18:55:00 -0500)│~ 8 if len(items) > 0 { +e9949066 (Ricardo Gerardi 2018-12-05 18:17:19 -0500)│ 9 for _, i := range items { +e9949066 (Ricardo Gerardi 2018-12-05 18:17:19 -0500)│ 10 fmt.Println(i) +00000000 (Not Committed Yet 2018-12-05 18:55:00 -0500)│+ 11 fmt.Println("------") +e9949066 (Ricardo Gerardi 2018-12-05 18:17:19 -0500)│ 12 } +e9949066 (Ricardo Gerardi 2018-12-05 18:17:19 -0500)│ 13 } +e9949066 (Ricardo Gerardi 2018-12-05 18:17:19 -0500)│ 14 } +``` + +You can see that lines 8 and 11 have not been committed. Check the repository status by typing **:Gstatus** : + +``` + 1 # On branch master + 2 # Your branch is up to date with 'origin/master'. + 3 # + 4 # Changes not staged for commit: + 5 # (use "git addVim plugins are awesome !
+..." to update what will be committed) + 6 # (use "git checkout -- ..." to discard changes in working directory) + 7 # + 8 # modified: vim-5plugins/examples/test1.go + 9 # + 10 no changes added to commit (use "git add" and/or "git commit -a") +-------------------------------------------------------------------------------------------------------- + 1 package main + 2 + 3 import "fmt" + 4 +_ 5 func main() { + 6 items := []string{"tv", "pc", "tablet"} + 7 +~ 8 if len(items) > 0 { + 9 for _, i := range items { + 10 fmt.Println(i) ++ 11 fmt.Println("------") + 12 } + 13 } + 14 } +``` + +Vim Fugitive opens a split window with the result of **git status**. You can stage a file for commit by pressing the **-** key on the line with the name of the file. You can reset the status by pressing **-** again. The message updates to reflect the new status: + +``` + 1 # On branch master + 2 # Your branch is up to date with 'origin/master'. + 3 # + 4 # Changes to be committed: + 5 # (use "git reset HEAD ..." to unstage) + 6 # + 7 # modified: vim-5plugins/examples/test1.go + 8 # +-------------------------------------------------------------------------------------------------------- + 1 package main + 2 + 3 import "fmt" + 4 +_ 5 func main() { + 6 items := []string{"tv", "pc", "tablet"} + 7 +~ 8 if len(items) > 0 { + 9 for _, i := range items { + 10 fmt.Println(i) ++ 11 fmt.Println("------") + 12 } + 13 } + 14 } +``` + +Now you can use the command **:Gcommit** to commit the changes. Vim Fugitive opens another split that allows you to enter a commit message: + +``` + 1 vim-5plugins: Updated test1.go example file + 2 # Please enter the commit message for your changes. Lines starting + 3 # with '#' will be ignored, and an empty message aborts the commit. + 4 # + 5 # On branch master + 6 # Your branch is up to date with 'origin/master'. + 7 # + 8 # Changes to be committed: + 9 # modified: vim-5plugins/examples/test1.go + 10 # +``` + +Save the file with **:wq** to complete the commit: + +``` +[master c3bf80f] vim-5plugins: Updated test1.go example file + 1 file changed, 2 insertions(+), 2 deletions(-) +Press ENTER or type command to continue +``` + +You can use **:Gstatus** again to see the result and **:Gpush** to update the remote repository with the new commit. + +``` + 1 # On branch master + 2 # Your branch is ahead of 'origin/master' by 1 commit. + 3 # (use "git push" to publish your local commits) + 4 # + 5 nothing to commit, working tree clean +``` + +If you like Vim Fugitive and want to learn more, the GitHub repository has links to screencasts showing additional functionality and workflows. Check it out! + +### What's next? + +These Vim plugins help developers write code in any programming language. There are two other categories of plugins to help developers: code-completion plugins and syntax-checker plugins. They are usually related to specific programming languages, so I will cover them in a follow-up article. + +Do you have another Vim plugin you use when writing code? Please share it in the comments below. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/vim-plugins-developers + +作者：[Ricardo Gerardi][a] +选题：[lujun9972][b] +译者：[pityonline](https://github.com/pityonline) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/rgerardi +[b]: https://github.com/lujun9972 +[1]: https://www.vim.org/ +[2]: https://www.vim.org/scripts/script.php?script_id=3599 +[3]: https://github.com/jiangmiao/auto-pairs +[4]: https://github.com/scrooloose/nerdcommenter +[5]: http://vim.wikia.com/wiki/Filetype.vim +[6]: https://www.vim.org/scripts/script.php?script_id=1697 +[7]: https://github.com/tpope/vim-surround +[8]: https://github.com/airblade/vim-gitgutter +[9]: https://www.vim.org/scripts/script.php?script_id=2975 +[10]: https://github.com/tpope/vim-fugitive diff --git a/sources/tech/20190111 Build a retro gaming console with RetroPie.md b/sources/tech/20190111 Build a retro gaming console with RetroPie.md new file mode 100644 index 0000000000..eedac575c9 --- /dev/null +++ b/sources/tech/20190111 Build a retro gaming console with RetroPie.md @@ -0,0 +1,82 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Build a retro gaming console with RetroPie) +[#]: via: (https://opensource.com/article/19/1/retropie) +[#]: author: (Jay LaCroix https://opensource.com/users/jlacroix) + +Build a retro gaming console with RetroPie +====== +Play your favorite classic Nintendo, Sega, and Sony console games on Linux. + + +The most common question I get on [my YouTube channel][1] and in person is what my favorite Linux distribution is. If I limit the answer to what I run on my desktops and laptops, my answer will typically be some form of an Ubuntu-based Linux distro. My honest answer to this question may surprise many. My favorite Linux distribution is actually [RetroPie][2]. + +As passionate as I am about Linux and open source software, I'm equally passionate about classic gaming, specifically video games produced in the '90s and earlier. I spend most of my surplus income on older games, and I now have a collection of close to a thousand games for over 20 gaming consoles. In my spare time, I raid flea markets, yard sales, estate sales, and eBay buying games for various consoles, including almost every iteration made by Nintendo, Sega, and Sony. There's something about classic games that I adore, a charm that seems lost in games released nowadays. + +Unfortunately, collecting retro games has its fair share of challenges. Cartridges with memory for save files will lose their charge over time, requiring the battery to be replaced. While it's not hard to replace save batteries (if you know how), it's still time-consuming. Games on CD-ROMs are subject to disc rot, which means that even if you take good care of them, they'll still lose data over time and become unplayable. Also, sometimes it's difficult to find replacement parts for some consoles. This wouldn't be so much of an issue if the majority of classic games were available digitally, but the vast majority are never re-released on a digital platform. + +### Gaming on RetroPie + +RetroPie is a great project and an asset to retro gaming enthusiasts like me. RetroPie is a Raspbian-based distribution designed for use on the Raspberry Pi (though it is possible to get it working on other platforms, such as a PC). RetroPie boots into a graphical interface that is completely controllable via a gamepad or joystick and allows you to easily manage digital copies (ROMs) of your favorite games. You can scrape information from the internet to organize your collection better and manage lists of favorite games, and the entire interface is very user-friendly and efficient. From the interface, you can launch directly into a game, then exit the game by pressing a combination of buttons on your gamepad. You rarely need a keyboard, unless you have to enter your WiFi password or manually edit configuration files. + +I use RetroPie to host a digital copy of every physical game I own in my collection. When I purchase a game from a local store or eBay, I also download the ROM. As a collector, this is very convenient. If I don't have a particular physical console within arms reach, I can boot up RetroPie and enjoy a game quickly without having to connect cables or clean cartridge contacts. There's still something to be said about playing a game on the original hardware, but if I'm pressed for time, RetroPie is very convenient. I also don't have to worry about dead save batteries, dirty cartridge contacts, disc rot, or any of the other issues collectors like me have to regularly deal with. I simply play the game. + +Also, RetroPie allows me to be very clever and utilize my technical know-how to achieve additional functionality that's not normally available. For example, I have three RetroPies set up, each of them synchronizing their files between each other by leveraging [Syncthing][3], a popular open source file synchronization tool. The synchronization happens automatically, and it means I can start a game on one television and continue in the same place on another unit since the save files are included in the synchronization. To take it a step further, I also back up my save and configuration files to [Backblaze B2][4], so I'm protected if an SD card becomes defective. + +### Setting up RetroPie + +Setting up RetroPie is very easy, and if you've ever set up a Raspberry Pi Linux distribution before (such as Raspbian) the process is essentially the same—you simply download the IMG file and flash it to your SD card by utilizing another tool, such as [Etcher][5], and insert it into your RetroPie. Then plug in an AC adapter and gamepad and hook it up to your television via HDMI. Optionally, you can buy a case to protect your RetroPie from outside elements and add visual appeal. Here is a listing of things you'll need to get started: + + * Raspberry Pi board (Model 3B+ or higher recommended) + * SD card (16GB or larger recommended) + * A USB gamepad + * UL-listed micro USB power adapter, at least 2.5 amp + + + +If you choose to add the optional Raspberry Pi case, I recommend the Super NES and Super Famicom themed cases from [RetroFlag][6]. Not only do these cases look cool, but they also have fully functioning power and reset buttons. This means you can configure the reset and power buttons to directly trigger the operating system's halt process, rather than abruptly terminating power. This definitely makes for a more professional experience, but it does require the installation of a special script. The instructions are on [RetroFlag's GitHub page][7]. Be wary: there are many cases available on Amazon and eBay of varying quality. Some of them are cheap knock-offs of RetroFlag cases, and others are just a lower quality overall. In fact, even cases by RetroFlag vary in quality—I had some power-distribution issues with the NES-themed case that made for an unstable experience. If in doubt, I've found that RetroFlag's Super NES and Super Famicom themed cases work very well. + +### Adding games + +When you boot RetroPie for the first time, it will resize the filesystem to ensure you have full access to the available space on your SD card and allow you to set up your gamepad. I can't give you links for game ROMs, so I'll leave that part up to you to figure out. When you've found them, simply add them to the RetroPie SD card in the designated folder, which would be located under **/home/pi/RetroPie/roms/ **. You can use your favorite tool for transferring the ROMs to the Pi, such as [SCP][8] in a terminal, [WinSCP][9], [Samba][10], etc. Once you've added the games, you can rescan them by pressing start and choosing the option to restart EmulationStation. When it restarts, it should automatically add menu entries for the ROMs you've added. That's basically all there is to it. + +(The rescan updates EmulationStation’s game inventory. If you don’t do that, it won’t list any newly added games you copy over.) + +Regarding the games' performance, your mileage will vary depending on which consoles you're emulating. For example, I've noticed that Sega Dreamcast games barely run at all, and most Nintendo 64 games will run sluggishly with a bad framerate. Many PlayStation Portable (PSP) games also perform inconsistently. However, all of the 8-bit and 16-bit consoles emulate seemingly perfectly—I haven't run into a single 8-bit or 16-bit game that doesn't run well. Surprisingly, games designed for the original PlayStation run great for me, which is a great feat considering the lower-performance potential of the Raspberry Pi. + +Overall, RetroPie's performance is great, but the Raspberry Pi is not as powerful as a gaming PC, so adjust your expectations accordingly. + +### Conclusion + +RetroPie is a fantastic open source project dedicated to preserving classic games and an asset to game collectors everywhere. Having a digital copy of my physical game collection is extremely convenient. If I were to tell my childhood self that one day I could have an entire game collection on one device, I probably wouldn't believe it. But RetroPie has become a staple in my household and provides hours of fun and enjoyment. + +If you want to see the parts I mentioned as well as a quick installation overview, I have [a video][11] on [my YouTube channel][12] that goes over the process and shows off some gameplay at the end. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/retropie + +作者：[Jay LaCroix][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/jlacroix +[b]: https://github.com/lujun9972 +[1]: https://www.youtube.com/channel/UCxQKHvKbmSzGMvUrVtJYnUA +[2]: https://retropie.org.uk/ +[3]: https://syncthing.net/ +[4]: https://www.backblaze.com/b2/cloud-storage.html +[5]: https://www.balena.io/etcher/ +[6]: https://www.amazon.com/shop/learnlinux.tv?listId=1N9V89LEH5S8K +[7]: https://github.com/RetroFlag/retroflag-picase +[8]: https://en.wikipedia.org/wiki/Secure_copy +[9]: https://winscp.net/eng/index.php +[10]: https://www.samba.org/ +[11]: https://www.youtube.com/watch?v=D8V-KaQzsWM +[12]: http://www.youtube.com/c/LearnLinuxtv diff --git a/sources/tech/20190111 Top 5 Linux Distributions for Productivity.md b/sources/tech/20190111 Top 5 Linux Distributions for Productivity.md new file mode 100644 index 0000000000..fbd8b9d120 --- /dev/null +++ b/sources/tech/20190111 Top 5 Linux Distributions for Productivity.md @@ -0,0 +1,170 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Top 5 Linux Distributions for Productivity) +[#]: via: (https://www.linux.com/blog/learn/2019/1/top-5-linux-distributions-productivity) +[#]: author: (Jack Wallen https://www.linux.com/users/jlwallen) + +Top 5 Linux Distributions for Productivity +====== + + + +I have to confess, this particular topic is a tough one to address. Why? First off, Linux is a productive operating system by design. Thanks to an incredibly reliable and stable platform, getting work done is easy. Second, to gauge effectiveness, you have to consider what type of work you need a productivity boost for. General office work? Development? School? Data mining? Human resources? You see how this question can get somewhat complicated. + +That doesn’t mean, however, that some distributions aren’t able to do a better job of configuring and presenting that underlying operating system into an efficient platform for getting work done. Quite the contrary. Some distributions do a much better job of “getting out of the way,” so you don’t find yourself in a work-related hole, having to dig yourself out and catch up before the end of day. These distributions help strip away the complexity that can be found in Linux, thereby making your workflow painless. + +Let’s take a look at the distros I consider to be your best bet for productivity. To help make sense of this, I’ve divided them into categories of productivity. That task itself was challenging, because everyone’s productivity varies. For the purposes of this list, however, I’ll look at: + + * General Productivity: For those who just need to work efficiently on multiple tasks. + + * Graphic Design: For those that work with the creation and manipulation of graphic images. + + * Development: For those who use their Linux desktops for programming. + + * Administration: For those who need a distribution to facilitate their system administration tasks. + + * Education: For those who need a desktop distribution to make them more productive in an educational environment. + + + + +Yes, there are more categories to be had, many of which can get very niche-y, but these five should fill most of your needs. + +### General Productivity + +For general productivity, you won’t get much more efficient than [Ubuntu][1]. The primary reason for choosing Ubuntu for this category is the seamless integration of apps, services, and desktop. You might be wondering why I didn’t choose Linux Mint for this category? Because Ubuntu now defaults to the GNOME desktop, it gains the added advantage of GNOME Extensions (Figure 1). + +![GNOME Clipboard][3] + +Figure 1: The GNOME Clipboard Indicator extension in action. + +[Used with permission][4] + +These extensions go a very long way to aid in boosting productivity (so Ubuntu gets the nod over Mint). But Ubuntu didn’t just accept a vanilla GNOME desktop. Instead, they tweaked it to make it slightly more efficient and user-friendly, out of the box. And because Ubuntu contains just the right mixture of default, out-of-the-box, apps (that just work), it makes for a nearly perfect platform for productivity. + +Whether you need to write a paper, work on a spreadsheet, code a new app, work on your company website, create marketing images, administer a server or network, or manage human resources from within your company HR tool, Ubuntu has you covered. The Ubuntu desktop distribution also doesn’t require the user to jump through many hoops to get things working … it simply works (and quite well). Finally, thanks to it’s Debian base, Ubuntu makes installing third-party apps incredibly easy. + +Although Ubuntu tends to be the go-to for nearly every list of “top distributions for X,” it’s very hard to argue against this particular distribution topping the list of general productivity distributions. + +### Graphic Design + +If you’re looking to up your graphic design productivity, you can’t go wrong with [Fedora Design Suite][5]. This Fedora respin was created by the team responsible for all Fedora-related art work. Although the default selection of apps isn’t a massive collection of tools, those it does include are geared specifically for the creation and manipulation of images. + +With apps like GIMP, Inkscape, Darktable, Krita, Entangle, Blender, Pitivi, Scribus, and more (Figure 2), you’ll find everything you need to get your image editing jobs done and done well. But Fedora Design Suite doesn’t end there. This desktop platform also includes a bevy of tutorials that cover countless subjects for many of the installed applications. For anyone trying to be as productive as possible, this is some seriously handy information to have at the ready. I will say, however, the tutorial entry in the GNOME Favorites is nothing more than a link to [this page][6]. + +![Fedora Design Suite Favorites][8] + +Figure 2: The Fedora Design Suite Favorites menu includes plenty of tools for getting your graphic design on. + +[Used with permission][4] + +Those that work with a digital camera will certainly appreciate the inclusion of the Entangle app, which allows you to control your DSLR from the desktop. + +### Development + +Nearly all Linux distributions are great platforms for programmers. However, one particular distributions stands out, above the rest, as one of the most productive tools you’ll find for the task. That OS comes from [System76][9] and it’s called [Pop!_OS][10]. Pop!_OS is tailored specifically for creators, but not of the artistic type. Instead, Pop!_OS is geared toward creators who specialize in developing, programming, and making. If you need an environment that is not only perfected suited for your development work, but includes a desktop that’s sure to get out of your way, you won’t find a better option than Pop!_OS (Figure 3). + +What might surprise you (given how “young” this operating system is), is that Pop!_OS is also one of the single most stable GNOME-based platforms you’ll ever use. This means Pop!_OS isn’t just for creators and makers, but anyone looking for a solid operating system. One thing that many users will greatly appreciate with Pop!_OS, is that you can download an ISO specifically for your video hardware. If you have Intel hardware, [download][10] the version for Intel/AMD. If your graphics card is NVIDIA, download that specific release. Either way, you are sure go get a solid platform for which to create your masterpiece. + +![Pop!_OS][12] + +Figure 3: The Pop!_OS take on GNOME Overview. + +[Used with permission][4] + +Interestingly enough, with Pop!_OS, you won’t find much in the way of pre-installed development tools. You won’t find an included IDE, or many other dev tools. You can, however, find all the development tools you need in the Pop Shop. + +### Administration + +If you’re looking to find one of the most productive distributions for admin tasks, look no further than [Debian][13]. Why? Because Debian is not only incredibly reliable, it’s one of those distributions that gets out of your way better than most others. Debian is the perfect combination of ease of use and unlimited possibility. On top of which, because this is the distribution for which so many others are based, you can bet if there’s an admin tool you need for a task, it’s available for Debian. Of course, we’re talking about general admin tasks, which means most of the time you’ll be using a terminal window to SSH into your servers (Figure 4) or a browser to work with web-based GUI tools on your network. Why bother making use of a desktop that’s going to add layers of complexity (such as SELinux in Fedora, or YaST in openSUSE)? Instead, chose simplicity. + +![Debian][15] + +Figure 4: SSH’ing into a remote server on Debian. + +[Used with permission][4] + +And because you can select which desktop you want (from GNOME, Xfce, KDE, Cinnamon, MATE, LXDE), you can be sure to have the interface that best matches your work habits. + +### Education + +If you are a teacher or student, or otherwise involved in education, you need the right tools to be productive. Once upon a time, there existed the likes of Edubuntu. That distribution never failed to be listed in the top of education-related lists. However, that distro hasn’t been updated since it was based on Ubuntu 14.04. Fortunately, there’s a new education-based distribution ready to take that title, based on openSUSE. This spin is called [openSUSE:Education-Li-f-e][16] (Linux For Education - Figure 5), and is based on openSUSE Leap 42.1 (so it is slightly out of date). + +openSUSE:Education-Li-f-e includes tools like: + + * Brain Workshop - A dual n-back brain exercise + + * GCompris - An educational software suite for young children + + * gElemental - A periodic table viewer + + * iGNUit - A general purpose flash card program + + * Little Wizard - Development environment for children based on Pascal + + * Stellarium - An astronomical sky simulator + + * TuxMath - An math tutor game + + * TuxPaint - A drawing program for young children + + * TuxType - An educational typing tutor for children + + * wxMaxima - A cross platform GUI for the computer algebra system + + * Inkscape - Vector graphics program + + * GIMP - Graphic image manipulation program + + * Pencil - GUI prototyping tool + + * Hugin - Panorama photo stitching and HDR merging program + + +![Education][18] + +Figure 5: The openSUSE:Education-Li-f-e distro has plenty of tools to help you be productive in or for school. + +[Used with permission][4] + +Also included with openSUSE:Education-Li-f-e is the [KIWI-LTSP Server][19]. The KIWI-LTSP Server is a flexible, cost effective solution aimed at empowering schools, businesses, and organizations all over the world to easily install and deploy desktop workstations. Although this might not directly aid the student to be more productive, it certainly enables educational institutions be more productive in deploying desktops for students to use. For more information on setting up KIWI-LTSP, check out the openSUSE [KIWI-LTSP quick start guide][20]. + +Learn more about Linux through the free ["Introduction to Linux" ][21]course from The Linux Foundation and edX. + +-------------------------------------------------------------------------------- + +via: https://www.linux.com/blog/learn/2019/1/top-5-linux-distributions-productivity + +作者：[Jack Wallen][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.linux.com/users/jlwallen +[b]: https://github.com/lujun9972 +[1]: https://www.ubuntu.com/ +[2]: /files/images/productivity1jpg +[3]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/productivity_1.jpg?itok=yxez3X1w (GNOME Clipboard) +[4]: /licenses/category/used-permission +[5]: https://labs.fedoraproject.org/en/design-suite/ +[6]: https://fedoraproject.org/wiki/Design_Suite/Tutorials +[7]: /files/images/productivity2jpg +[8]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/productivity_2.jpg?itok=ke0b8qyH (Fedora Design Suite Favorites) +[9]: https://system76.com/ +[10]: https://system76.com/pop +[11]: /files/images/productivity3jpg-0 +[12]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/productivity_3_0.jpg?itok=8UkCUfsD (Pop!_OS) +[13]: https://www.debian.org/ +[14]: /files/images/productivity4jpg +[15]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/productivity_4.jpg?itok=c9yD3Xw2 (Debian) +[16]: https://en.opensuse.org/openSUSE:Education-Li-f-e +[17]: /files/images/productivity5jpg +[18]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/productivity_5.jpg?itok=oAFtV8nT (Education) +[19]: https://en.opensuse.org/Portal:KIWI-LTSP +[20]: https://en.opensuse.org/SDB:KIWI-LTSP_quick_start +[21]: https://training.linuxfoundation.org/linux-courses/system-administration-training/introduction-to-linux diff --git a/sources/tech/20190113 Editing Subtitles in Linux.md b/sources/tech/20190113 Editing Subtitles in Linux.md new file mode 100644 index 0000000000..1eaa6a68fd --- /dev/null +++ b/sources/tech/20190113 Editing Subtitles in Linux.md @@ -0,0 +1,168 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Editing Subtitles in Linux) +[#]: via: (https://itsfoss.com/editing-subtitles) +[#]: author: (Shirish https://itsfoss.com/author/shirish/) + +Editing Subtitles in Linux +====== + +I have been a world movie and regional movies lover for decades. Subtitles are the essential tool that have enabled me to enjoy the best movies in various languages and from various countries. + +If you enjoy watching movies with subtitles, you might have noticed that sometimes the subtitles are not synced or not correct. + +Did you know that you can edit subtitles and make them better? Let me show you some basic subtitle editing in Linux. + +![Editing subtitles in Linux][1] + +### Extracting subtitles from closed captions data + +Around 2012, 2013 I came to know of a tool called [CCEextractor.][2] As time passed, it has become one of the vital tools for me, especially if I come across a media file which has the subtitle embedded in it. + +CCExtractor analyzes video files and produces independent subtitle files from the closed captions data. + +CCExtractor is a cross-platform, free and open source tool. The tool has matured quite a bit from its formative years and has been part of [GSOC][3] and Google Code-in now and [then.][4] + +The tool, to put it simply, is more or less a set of scripts which work one after another in a serialized order to give you an extracted subtitle. + +You can follow the installation instructions for CCExtractor on [this page][5]. + +After installing when you want to extract subtitles from a media file, do the following: + +``` +ccextractor +``` + +The output of the command will be something like this: + +It basically scans the media file. In this case, it found that the media file is in malyalam and that the media container is an [.mkv][6] container. It extracted the subtitle file with the same name as the video file adding _eng to it. + +CCExtractor is a wonderful tool which can be used to enhance subtitles along with Subtitle Edit which I will share in the next section. + +``` +Interesting Read: There is an interesting synopsis of subtitles at [vicaps][7] which tells and shares why subtitles are important to us. It goes into quite a bit of detail of movie-making as well for those interested in such topics. +``` + +### Editing subtitles with SubtitleEditor Tool + +You probably are aware that most subtitles are in [.srt format][8] . The beautiful thing about this format is and was you could load it in your text editor and do little fixes in it. + +A srt file looks something like this when launched into a simple text-editor: + +The excerpt subtitle I have shared is from a pretty Old German Movie called [The Cabinet of Dr. Caligari (1920)][9] + +Subtitleeditor is a wonderful tool when it comes to editing subtitles. Subtitle Editor is and can be used to manipulate time duration, frame-rate of the subtitle file to be in sync with the media file, duration of breaks in-between and much more. I’ll share some of the basic subtitle editing here. + +![][10] + +First install subtitleeditor the same way you installed ccextractor, using your favorite installation method. In Debian, you can use this command: + +``` +sudo apt install subtitleeditor +``` + +When you have it installed, let’s see some of the common scenarios where you need to edit a subtitle. + +#### Manipulating Frame-rates to sync with Media file + +If you find that the subtitles are not synced with the video, one of the reasons could be the difference between the frame rates of the video file and the subtitle file. + +How do you know the frame rates of these files, then? + +To get the frame rate of a video file, you can use the mediainfo tool. You may need to install it first using your distribution’s package manager. + +Using mediainfo is simple: + +``` +$ mediainfo somefile.mkv | grep Frame + Format settings : CABAC / 4 Ref Frames + Format settings, ReFrames : 4 frames + Frame rate mode : Constant + Frame rate : 25.000 FPS + Bits/(Pixel*Frame) : 0.082 + Frame rate : 46.875 FPS (1024 SPF) +``` + +Now you can see that framerate of the video file is 25.000 FPS. The other Frame-rate we see is for the audio. While I can share why particular fps are used in Video-encoding, Audio-encoding etc. it would be a different subject matter. There is a lot of history associated with it. + +Next is to find out the frame rate of the subtitle file and this is a slightly complicated. + +Usually, most subtitles are in a zipped format. Unzipping the .zip archive along with the subtitle file which ends in something.srt. Along with it, there is usually also a .info file with the same name which sometime may have the frame rate of the subtitle. + +If not, then it usually is a good idea to go some site and download the subtitle from a site which has that frame rate information. For this specific German file, I will be using [Opensubtitle.org][11] + +As you can see in the link, the frame rate of the subtitle is 23.976 FPS. Quite obviously, it won’t play well with my video file with frame rate 25.000 FPS. + +In such cases, you can change the frame rate of the subtitle file using the Subtitle Editor tool: + +Select all the contents from the subtitle file by doing CTRL+A. Go to Timings -> Change Framerate and change frame rates from 23.976 fps to 25.000 fps or whatever it is that is desired. Save the changed file. + +![synchronize frame rates of subtitles in Linux][12] + +#### Changing the Starting position of a subtitle file + +Sometimes the above method may be enough, sometimes though it will not be enough. + +You might find some cases when the start of the subtitle file is different from that in the movie or a media file while the frame rate is the same. + +In such cases, do the following: + +Select all the contents from the subtitle file by doing CTRL+A. Go to Timings -> Select Move Subtitle. + +![Move subtitles using Subtitle Editor on Linux][13] + +Change the new Starting position of the subtitle file. Save the changed file. + +![Move subtitles using Subtitle Editor in Linux][14] + +If you wanna be more accurate, then use [mpv][15] to see the movie or media file and click on the timing, if you click on the timing bar which shows how much the movie or the media file has elapsed, clicking on it will also reveal the microsecond. + +I usually like to be accurate so I try to be as precise as possible. It is very difficult in MPV as human reaction time is imprecise. If I wanna be super accurate then I use something like [Audacity][16] but then that is another ball-game altogether as you can do so much more with it. That may be something to explore in a future blog post as well. + +#### Manipulating Duration + +Sometimes even doing both is not enough and you even have to shrink or add the duration to make it sync with the media file. This is one of the more tedious works as you have to individually fix the duration of each sentence. This can happen especially if you have variable frame rates in the media file (nowadays rare but you still get such files). + +In such a scenario, you may have to edit the duration manually and automation is not possible. The best way is either to fix the video file (not possible without degrading the video quality) or getting video from another source at a higher quality and then [transcode][17] it with the settings you prefer. This again, while a major undertaking I could shed some light on in some future blog post. + +### Conclusion + +What I have shared in above is more or less on improving on existing subtitle files. If you were to start a scratch you need loads of time. I haven’t shared that at all because a movie or any video material of say an hour can easily take anywhere from 4-6 hours or even more depending upon skills of the subtitler, patience, context, jargon, accents, native English speaker, translator etc. all of which makes a difference to the quality of the subtitle. + +I hope you find this interesting and from now onward, you’ll handle your subtitles slightly better. If you have any suggestions to add, please leave a comment below. + + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/editing-subtitles + +作者：[Shirish][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://itsfoss.com/author/shirish/ +[b]: https://github.com/lujun9972 +[1]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/01/editing-subtitles-in-linux.jpeg?resize=800%2C450&ssl=1 +[2]: https://www.ccextractor.org/ +[3]: https://itsfoss.com/best-open-source-internships/ +[4]: https://www.ccextractor.org/public:codein:google_code-in_2018 +[5]: https://github.com/CCExtractor/ccextractor/wiki/Installation +[6]: https://en.wikipedia.org/wiki/Matroska +[7]: https://www.vicaps.com/blog/history-of-silent-movies-and-subtitles/ +[8]: https://en.wikipedia.org/wiki/SubRip#SubRip_text_file_format +[9]: https://www.imdb.com/title/tt0010323/ +[10]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/12/subtitleeditor.jpg?ssl=1 +[11]: https://www.opensubtitles.org/en/search/sublanguageid-eng/idmovie-4105 +[12]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/01/subtitleeditor-frame-rate-sync.jpg?resize=800%2C450&ssl=1 +[13]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/01/Move-subtitles-Caligiri.jpg?resize=800%2C450&ssl=1 +[14]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/move-subtitles.jpg?ssl=1 +[15]: https://itsfoss.com/mpv-video-player/ +[16]: https://www.audacityteam.org/ +[17]: https://en.wikipedia.org/wiki/Transcoding +[18]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/01/editing-subtitles-in-linux.jpeg?fit=800%2C450&ssl=1 diff --git a/sources/tech/20190116 Zipping files on Linux- the many variations and how to use them.md b/sources/tech/20190116 Zipping files on Linux- the many variations and how to use them.md new file mode 100644 index 0000000000..fb98f78b06 --- /dev/null +++ b/sources/tech/20190116 Zipping files on Linux- the many variations and how to use them.md @@ -0,0 +1,324 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Zipping files on Linux: the many variations and how to use them) +[#]: via: (https://www.networkworld.com/article/3333640/linux/zipping-files-on-linux-the-many-variations-and-how-to-use-them.html) +[#]: author: (Sandra Henry-Stocker https://www.networkworld.com/author/Sandra-Henry_Stocker/) + +Zipping files on Linux: the many variations and how to use them +====== + + +Some of us have been zipping files on Unix and Linux systems for many decades — to save some disk space and package files together for archiving. Even so, there are some interesting variations on zipping that not all of us have tried. So, in this post, we’re going to look at standard zipping and unzipping as well as some other interesting zipping options. + +### The basic zip command + +First, let’s look at the basic **zip** command. It uses what is essentially the same compression algorithm as **gzip** , but there are a couple important differences. For one thing, the gzip command is used only for compressing a single file where zip can both compress files and join them together into an archive. For another, the gzip command zips “in place”. In other words, it leaves a compressed file — not the original file alongside the compressed copy. Here's an example of gzip at work: + +``` +$ gzip onefile +$ ls -l +-rw-rw-r-- 1 shs shs 10514 Jan 15 13:13 onefile.gz +``` + +And here's zip. Notice how this command requires that a name be provided for the zipped archive where gzip simply uses the original file name and adds the .gz extension. + +``` +$ zip twofiles.zip file* + adding: file1 (deflated 82%) + adding: file2 (deflated 82%) +$ ls -l +-rw-rw-r-- 1 shs shs 58021 Jan 15 13:25 file1 +-rw-rw-r-- 1 shs shs 58933 Jan 15 13:34 file2 +-rw-rw-r-- 1 shs shs 21289 Jan 15 13:35 twofiles.zip +``` + +Notice also that the original files are still sitting there. + +The amount of disk space that is saved (i.e., the degree of compression obtained) will depend on the content of each file. The variation in the example below is considerable. + +``` +$ zip mybin.zip ~/bin/* + adding: bin/1 (deflated 26%) + adding: bin/append (deflated 64%) + adding: bin/BoD_meeting (deflated 18%) + adding: bin/cpuhog1 (deflated 14%) + adding: bin/cpuhog2 (stored 0%) + adding: bin/ff (deflated 32%) + adding: bin/file.0 (deflated 1%) + adding: bin/loop (deflated 14%) + adding: bin/notes (deflated 23%) + adding: bin/patterns (stored 0%) + adding: bin/runme (stored 0%) + adding: bin/tryme (deflated 13%) + adding: bin/tt (deflated 6%) +``` + +### The unzip command + +The **unzip** command will recover the contents from a zip file and, as you'd likely suspect, leave the zip file intact, whereas a similar gunzip command would leave only the uncompressed file. + +``` +$ unzip twofiles.zip +Archive: twofiles.zip + inflating: file1 + inflating: file2 +$ ls -l +-rw-rw-r-- 1 shs shs 58021 Jan 15 13:25 file1 +-rw-rw-r-- 1 shs shs 58933 Jan 15 13:34 file2 +-rw-rw-r-- 1 shs shs 21289 Jan 15 13:35 twofiles.zip +``` + +### The zipcloak command + +The **zipcloak** command encrypts a zip file, prompting you to enter a password twice (to help ensure you don't "fat finger" it) and leaves the file in place. You can expect the file size to vary a little from the original. + +``` +$ zipcloak twofiles.zip +Enter password: +Verify password: +encrypting: file1 +encrypting: file2 +$ ls -l +total 204 +-rw-rw-r-- 1 shs shs 58021 Jan 15 13:25 file1 +-rw-rw-r-- 1 shs shs 58933 Jan 15 13:34 file2 +-rw-rw-r-- 1 shs shs 21313 Jan 15 13:46 twofiles.zip <== slightly larger than + unencrypted version +``` + +Keep in mind that the original files are still sitting there unencrypted. + +### The zipdetails command + +The **zipdetails** command is going to show you details — a _lot_ of details about a zipped file, likely a lot more than you care to absorb. Even though we're looking at an encrypted file, zipdetails does display the file names along with file modification dates, user and group information, file length data, etc. Keep in mind that this is all "metadata." We don't see the contents of the files. + +``` +$ zipdetails twofiles.zip + +0000 LOCAL HEADER #1 04034B50 +0004 Extract Zip Spec 14 '2.0' +0005 Extract OS 00 'MS-DOS' +0006 General Purpose Flag 0001 + [Bit 0] 1 'Encryption' + [Bits 1-2] 1 'Maximum Compression' +0008 Compression Method 0008 'Deflated' +000A Last Mod Time 4E2F6B24 'Tue Jan 15 13:25:08 2019' +000E CRC F1B115BD +0012 Compressed Length 00002904 +0016 Uncompressed Length 0000E2A5 +001A Filename Length 0005 +001C Extra Length 001C +001E Filename 'file1' +0023 Extra ID #0001 5455 'UT: Extended Timestamp' +0025 Length 0009 +0027 Flags '03 mod access' +0028 Mod Time 5C3E2584 'Tue Jan 15 13:25:08 2019' +002C Access Time 5C3E27BB 'Tue Jan 15 13:34:35 2019' +0030 Extra ID #0002 7875 'ux: Unix Extra Type 3' +0032 Length 000B +0034 Version 01 +0035 UID Size 04 +0036 UID 000003E8 +003A GID Size 04 +003B GID 000003E8 +003F PAYLOAD + +2943 LOCAL HEADER #2 04034B50 +2947 Extract Zip Spec 14 '2.0' +2948 Extract OS 00 'MS-DOS' +2949 General Purpose Flag 0001 + [Bit 0] 1 'Encryption' + [Bits 1-2] 1 'Maximum Compression' +294B Compression Method 0008 'Deflated' +294D Last Mod Time 4E2F6C56 'Tue Jan 15 13:34:44 2019' +2951 CRC EC214569 +2955 Compressed Length 00002913 +2959 Uncompressed Length 0000E635 +295D Filename Length 0005 +295F Extra Length 001C +2961 Filename 'file2' +2966 Extra ID #0001 5455 'UT: Extended Timestamp' +2968 Length 0009 +296A Flags '03 mod access' +296B Mod Time 5C3E27C4 'Tue Jan 15 13:34:44 2019' +296F Access Time 5C3E27BD 'Tue Jan 15 13:34:37 2019' +2973 Extra ID #0002 7875 'ux: Unix Extra Type 3' +2975 Length 000B +2977 Version 01 +2978 UID Size 04 +2979 UID 000003E8 +297D GID Size 04 +297E GID 000003E8 +2982 PAYLOAD + +5295 CENTRAL HEADER #1 02014B50 +5299 Created Zip Spec 1E '3.0' +529A Created OS 03 'Unix' +529B Extract Zip Spec 14 '2.0' +529C Extract OS 00 'MS-DOS' +529D General Purpose Flag 0001 + [Bit 0] 1 'Encryption' + [Bits 1-2] 1 'Maximum Compression' +529F Compression Method 0008 'Deflated' +52A1 Last Mod Time 4E2F6B24 'Tue Jan 15 13:25:08 2019' +52A5 CRC F1B115BD +52A9 Compressed Length 00002904 +52AD Uncompressed Length 0000E2A5 +52B1 Filename Length 0005 +52B3 Extra Length 0018 +52B5 Comment Length 0000 +52B7 Disk Start 0000 +52B9 Int File Attributes 0001 + [Bit 0] 1 Text Data +52BB Ext File Attributes 81B40000 +52BF Local Header Offset 00000000 +52C3 Filename 'file1' +52C8 Extra ID #0001 5455 'UT: Extended Timestamp' +52CA Length 0005 +52CC Flags '03 mod access' +52CD Mod Time 5C3E2584 'Tue Jan 15 13:25:08 2019' +52D1 Extra ID #0002 7875 'ux: Unix Extra Type 3' +52D3 Length 000B +52D5 Version 01 +52D6 UID Size 04 +52D7 UID 000003E8 +52DB GID Size 04 +52DC GID 000003E8 + +52E0 CENTRAL HEADER #2 02014B50 +52E4 Created Zip Spec 1E '3.0' +52E5 Created OS 03 'Unix' +52E6 Extract Zip Spec 14 '2.0' +52E7 Extract OS 00 'MS-DOS' +52E8 General Purpose Flag 0001 + [Bit 0] 1 'Encryption' + [Bits 1-2] 1 'Maximum Compression' +52EA Compression Method 0008 'Deflated' +52EC Last Mod Time 4E2F6C56 'Tue Jan 15 13:34:44 2019' +52F0 CRC EC214569 +52F4 Compressed Length 00002913 +52F8 Uncompressed Length 0000E635 +52FC Filename Length 0005 +52FE Extra Length 0018 +5300 Comment Length 0000 +5302 Disk Start 0000 +5304 Int File Attributes 0001 + [Bit 0] 1 Text Data +5306 Ext File Attributes 81B40000 +530A Local Header Offset 00002943 +530E Filename 'file2' +5313 Extra ID #0001 5455 'UT: Extended Timestamp' +5315 Length 0005 +5317 Flags '03 mod access' +5318 Mod Time 5C3E27C4 'Tue Jan 15 13:34:44 2019' +531C Extra ID #0002 7875 'ux: Unix Extra Type 3' +531E Length 000B +5320 Version 01 +5321 UID Size 04 +5322 UID 000003E8 +5326 GID Size 04 +5327 GID 000003E8 + +532B END CENTRAL HEADER 06054B50 +532F Number of this disk 0000 +5331 Central Dir Disk no 0000 +5333 Entries in this disk 0002 +5335 Total Entries 0002 +5337 Size of Central Dir 00000096 +533B Offset to Central Dir 00005295 +533F Comment Length 0000 +Done +``` + +### The zipgrep command + +The **zipgrep** command is going to use a grep-type feature to locate particular content in your zipped files. If the file is encrypted, you will need to enter the password provided for the encryption for each file you want to examine. If you only want to check the contents of a single file from the archive, add its name to the end of the zipgrep command as shown below. + +``` +$ zipgrep hazard twofiles.zip file1 +[twofiles.zip] file1 password: +Certain pesticides should be banned since they are hazardous to the environment. +``` + +### The zipinfo command + +The **zipinfo** command provides information on the contents of a zipped file whether encrypted or not. This includes the file names, sizes, dates and permissions. + +``` +$ zipinfo twofiles.zip +Archive: twofiles.zip +Zip file size: 21313 bytes, number of entries: 2 +-rw-rw-r-- 3.0 unx 58021 Tx defN 19-Jan-15 13:25 file1 +-rw-rw-r-- 3.0 unx 58933 Tx defN 19-Jan-15 13:34 file2 +2 files, 116954 bytes uncompressed, 20991 bytes compressed: 82.1% +``` + +### The zipnote command + +The **zipnote** command can be used to extract comments from zip archives or add them. To display comments, just preface the name of the archive with the command. If no comments have been added previously, you will see something like this: + +``` +$ zipnote twofiles.zip +@ file1 +@ (comment above this line) +@ file2 +@ (comment above this line) +@ (zip file comment below this line) +``` + +If you want to add comments, write the output from the zipnote command to a file: + +``` +$ zipnote twofiles.zip > comments +``` + +Next, edit the file you've just created, inserting your comments above the **(comment above this line)** lines. Then add the comments using a zipnote command like this one: + +``` +$ zipnote -w twofiles.zip < comments +``` + +### The zipsplit command + +The **zipsplit** command can be used to break a zip archive into multiple zip archives when the original file is too large — maybe because you're trying to add one of the files to a small thumb drive. The easiest way to do this seems to be to specify the max size for each of the zipped file portions. This size must be large enough to accomodate the largest included file. + +``` +$ zipsplit -n 12000 twofiles.zip +2 zip files will be made (100% efficiency) +creating: twofile1.zip +creating: twofile2.zip +$ ls twofile*.zip +-rw-rw-r-- 1 shs shs 10697 Jan 15 14:52 twofile1.zip +-rw-rw-r-- 1 shs shs 10702 Jan 15 14:52 twofile2.zip +-rw-rw-r-- 1 shs shs 21377 Jan 15 14:27 twofiles.zip +``` + +Notice how the extracted files are sequentially named "twofile1" and "twofile2". + +### Wrap-up + +The **zip** command, along with some of its zipping compatriots, provide a lot of control over how you generate and work with compressed file archives. + +**[ Also see:[Invaluable tips and tricks for troubleshooting Linux][1] ]** + +Join the Network World communities on [Facebook][2] and [LinkedIn][3] to comment on topics that are top of mind. + +-------------------------------------------------------------------------------- + +via: https://www.networkworld.com/article/3333640/linux/zipping-files-on-linux-the-many-variations-and-how-to-use-them.html + +作者：[Sandra Henry-Stocker][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.networkworld.com/author/Sandra-Henry_Stocker/ +[b]: https://github.com/lujun9972 +[1]: https://www.networkworld.com/article/3242170/linux/invaluable-tips-and-tricks-for-troubleshooting-linux.html +[2]: https://www.facebook.com/NetworkWorld/ +[3]: https://www.linkedin.com/company/network-world diff --git a/sources/tech/20190119 Get started with Roland, a random selection tool for the command line.md b/sources/tech/20190119 Get started with Roland, a random selection tool for the command line.md new file mode 100644 index 0000000000..edf787447b --- /dev/null +++ b/sources/tech/20190119 Get started with Roland, a random selection tool for the command line.md @@ -0,0 +1,90 @@ +[#]: collector: (lujun9972) +[#]: translator: (geekpi) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Get started with Roland, a random selection tool for the command line) +[#]: via: (https://opensource.com/article/19/1/productivity-tools-roland) +[#]: author: (Kevin Sonney https://opensource.com/users/ksonney (Kevin Sonney)) + +Get started with Roland, a random selection tool for the command line +====== + +Get help making hard choices with Roland, the seventh in our series on open source tools that will make you more productive in 2019. + + + +There seems to be a mad rush at the beginning of every year to find ways to be more productive. New Year's resolutions, the itch to start the year off right, and of course, an "out with the old, in with the new" attitude all contribute to this. And the usual round of recommendations is heavily biased towards closed source and proprietary software. It doesn't have to be that way. + +Here's the seventh of my picks for 19 new (or new-to-you) open source tools to help you be more productive in 2019. + +### Roland + +By the time the workday has ended, often the only thing I want to think about is hitting the couch and playing the video game of the week. But even though my professional obligations stop at the end of the workday, I still have to manage my household. Laundry, pet care, making sure my teenager has what he needs, and most important: deciding what to make for dinner. + +Like many people, I often suffer from [decision fatigue][1], and I make less-than-healthy choices for dinner based on speed, ease of preparation, and (quite frankly) whatever causes me the least stress. + + + +[Roland][2] makes planning my meals much easier. Roland is a Perl application designed for tabletop role-playing games. It picks randomly from a list of items, such as monsters and hirelings. In essence, Roland does the same thing at the command line that a game master does when rolling physical dice to look up things in a table from the Game Master's Big Book of Bad Things to Do to Players. + +With minor modifications, Roland can do so much more. For example, just by adding a table, I can enable Roland to help me choose what to cook for dinner. + +The first step is installing Roland and all its dependencies. + +``` +git clone git@github.com:rjbs/Roland.git +cpan install Getopt::Long::Descriptive Moose \ + namespace::autoclean List:AllUtils Games::Dice \ + Sort::ByExample Data::Bucketeer Text::Autoformat \ + YAML::XS +cd oland +``` + +Next, I create a YAML document named **dinner** and enter all our meal options. + +``` +type: list +pick: 1 +items: + - "frozen pizza" + - "chipotle black beans" + - "huevos rancheros" + - "nachos" + - "pork roast" + - "15 bean soup" + - "roast chicken" + - "pot roast" + - "grilled cheese sandwiches" +``` + +Running the command **bin/roland dinner** will read the file and pick one of the options. + + + +I like to plan for the week ahead so I can shop for all my ingredients in advance. The **pick** command determines how many items from the list to chose, and right now, the **pick** option is set to 1. If I want to plan a full week's dinner menu, I can just change **pick: 1** to **pick: 7** and it will give me a week's worth of dinners. You can also use the **-m** command line option to manually enter the choices. + + + +You can also do fun things with Roland, like adding a file named **8ball** with some classic phrases. + + + +You can create all kinds of files to help with common decisions that seem so stressful after a long day of work. And even if you don't use it for that, you can still use it to decide which devious trap to set up for tonight's game. + + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/productivity-tools-roland + +作者：[Kevin Sonney][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/ksonney (Kevin Sonney) +[b]: https://github.com/lujun9972 +[1]: https://en.wikipedia.org/wiki/Decision_fatigue +[2]: https://github.com/rjbs/Roland diff --git a/sources/tech/20190121 Akira- The Linux Design Tool We-ve Always Wanted.md b/sources/tech/20190121 Akira- The Linux Design Tool We-ve Always Wanted.md new file mode 100644 index 0000000000..bd58eca5bf --- /dev/null +++ b/sources/tech/20190121 Akira- The Linux Design Tool We-ve Always Wanted.md @@ -0,0 +1,92 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Akira: The Linux Design Tool We’ve Always Wanted?) +[#]: via: (https://itsfoss.com/akira-design-tool) +[#]: author: (Ankush Das https://itsfoss.com/author/ankush/) + +Akira: The Linux Design Tool We’ve Always Wanted? +====== + +Let’s make it clear, I am not a professional designer – but I’ve used certain tools on Windows (like Photoshop, Illustrator, etc.) and [Figma][1] (which is a browser-based interface design tool). I’m sure there are a lot more design tools available for Mac and Windows. + +Even on Linux, there is a limited number of dedicated [graphic design tools][2]. A few of these tools like [GIMP][3] and [Inkscape][4] are used by professionals as well. But most of them are not considered professional grade, unfortunately. + +Even if there are a couple more solutions – I’ve never come across a native Linux application that could replace [Sketch][5], Figma, or Adobe **** XD. Any professional designer would agree to that, isn’t it? + +### Is Akira going to replace Sketch, Figma, and Adobe XD on Linux? + +Well, in order to develop something that would replace those awesome proprietary tools – [Alessandro Castellani][6] – came up with a [Kickstarter campaign][7] by teaming up with a couple of experienced developers – +[Alberto Fanjul][8], [Bilal Elmoussaoui][9], and [Felipe Escoto][10]. + +So, yes, Akira is still pretty much just an idea- with a working prototype of its interface (as I observed in their [live stream session][11] via Kickstarter recently). + +### If it does not exist, why the Kickstarter campaign? + +![][12] + +The aim of the Kickstarter campaign is to gather funds in order to hire the developers and take a few months off to dedicate their time in order to make Akira possible. + +Nonetheless, if you want to support the project, you should know some details, right? + +Fret not, we asked a couple of questions in their livestream session – let’s get into it… + +### Akira: A few more details + +![Akira prototype interface][13] +Image Credits: Kickstarter + +As the Kickstarter campaign describes: + +> The main purpose of Akira is to offer a fast and intuitive tool to **create Web and Mobile interfaces** , more like **Sketch** , **Figma** , or **Adobe XD** , with a completely native experience for Linux. + +They’ve also written a detailed description as to how the tool will be different from Inkscape, Glade, or QML Editor. Of course, if you want all the technical details, [Kickstarter][7] is the way to go. But, before that, let’s take a look at what they had to say when I asked some questions about Akira. + +Q: If you consider your project – similar to what Figma offers – why should one consider installing Akira instead of using the web-based tool? Is it just going to be a clone of those tools – offering a native Linux experience or is there something really interesting to encourage users to switch (except being an open source solution)? + +**Akira:** A native experience on Linux is always better and fast in comparison to a web-based electron app. Also, the hardware configuration matters if you choose to utilize Figma – but Akira will be light on system resource and you will still be able to do similar stuff without needing to go online. + +Q: Let’s assume that it becomes the open source solution that Linux users have been waiting for (with similar features offered by proprietary tools). What are your plans to sustain it? Do you plan to introduce any pricing plans – or rely on donations? + +**Akira** : The project will mostly rely on Donations (something like [Krita Foundation][14] could be an idea). But, there will be no “pro” pricing plans – it will be available for free and it will be an open source project. + +So, with the response I got, it definitely seems to be something promising that we should probably support. + +### Wrapping Up + +What do you think about Akira? Is it just going to remain a concept? Or do you hope to see it in action? + +Let us know your thoughts in the comments below. + +![][15] + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/akira-design-tool + +作者：[Ankush Das][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://itsfoss.com/author/ankush/ +[b]: https://github.com/lujun9972 +[1]: https://www.figma.com/ +[2]: https://itsfoss.com/best-linux-graphic-design-software/ +[3]: https://itsfoss.com/gimp-2-10-release/ +[4]: https://inkscape.org/ +[5]: https://www.sketchapp.com/ +[6]: https://github.com/Alecaddd +[7]: https://www.kickstarter.com/projects/alecaddd/akira-the-linux-design-tool/description +[8]: https://github.com/albfan +[9]: https://github.com/bilelmoussaoui +[10]: https://github.com/Philip-Scott +[11]: https://live.kickstarter.com/alessandro-castellani/live-stream/the-current-state-of-akira +[12]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/01/akira-design-tool-kickstarter.jpg?resize=800%2C451&ssl=1 +[13]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/akira-mockup.png?ssl=1 +[14]: https://krita.org/en/about/krita-foundation/ +[15]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/01/akira-design-tool-kickstarter.jpg?fit=812%2C458&ssl=1 diff --git a/sources/tech/20190121 Get started with TaskBoard, a lightweight kanban board.md b/sources/tech/20190121 Get started with TaskBoard, a lightweight kanban board.md new file mode 100644 index 0000000000..e77e5e3b1c --- /dev/null +++ b/sources/tech/20190121 Get started with TaskBoard, a lightweight kanban board.md @@ -0,0 +1,59 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Get started with TaskBoard, a lightweight kanban board) +[#]: via: (https://opensource.com/article/19/1/productivity-tool-taskboard) +[#]: author: (Kevin Sonney https://opensource.com/users/ksonney (Kevin Sonney)) + +Get started with TaskBoard, a lightweight kanban board +====== +Check out the ninth tool in our series on open source tools that will make you more productive in 2019. + + + +There seems to be a mad rush at the beginning of every year to find ways to be more productive. New Year's resolutions, the itch to start the year off right, and of course, an "out with the old, in with the new" attitude all contribute to this. And the usual round of recommendations is heavily biased towards closed source and proprietary software. It doesn't have to be that way. + +Here's the ninth of my picks for 19 new (or new-to-you) open source tools to help you be more productive in 2019. + +### TaskBoard + +As I wrote in the [second article][1] in this series, [kanban boards][2] are pretty popular these days. And not all kanban boards are created equal. [TaskBoard][3] is a PHP application that is easy to set up on an existing web server and has a set of functions that make it easy to use and manage. + + + +[Installation][4] is as simple as unzipping the files on your web server, running a script or two, and making sure the correct directories are accessible. The first time you start it up, you're presented with a login form, and then it's time to start adding users and making boards. Board creation options include adding the columns you want to use and setting the default color of the cards. You can also assign users to boards so everyone sees only the boards they need to see. + +User management is lightweight, and all accounts are local to the server. You can set a default board for everyone on the server, and users can set their own default boards, too. These options can be useful when someone works on one board more than others. + + + +TaskBoard also allows you to create automatic actions, which are actions taken upon changes to user assignment, columns, or card categories. Although TaskBoard is not as powerful as some other kanban apps, you can set up automatic actions to make cards more visible for board users, clear due dates, and auto-assign new cards to people as needed. For example, in the screenshot below, if a card is assigned to the "admin" user, its color is changed to red, and when a card is assigned to my user, its color is changed to teal. I've also added an action to clear an item's due date if it's added to the "To-Do" column and to auto-assign cards to my user when that happens. + + + +The cards are very straightforward. While they don't have a start date, they do have end dates and a points field. Points can be used for estimating the time needed, effort required, or just general priority. Using points is optional, but if you are using TaskBoard for scrum planning or other agile techniques, it is a really handy feature. You can also filter the view by users and categories. This can be helpful on a team with multiple work streams going on, as it allows a team lead or manager to get status information about progress or a person's workload. + + + +If you need a reasonably lightweight kanban board, check out TaskBoard. It installs quickly, has some nice features, and is very, very easy to use. It's also flexible enough to be used for development teams, personal task tracking, and a whole lot more. + + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/productivity-tool-taskboard + +作者：[Kevin Sonney][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/ksonney (Kevin Sonney) +[b]: https://github.com/lujun9972 +[1]: https://opensource.com/article/19/1/productivity-tool-wekan +[2]: https://en.wikipedia.org/wiki/Kanban +[3]: https://taskboard.matthewross.me/ +[4]: https://taskboard.matthewross.me/docs/ diff --git a/sources/tech/20190121 How to Resize OpenStack Instance (Virtual Machine) from Command line.md b/sources/tech/20190121 How to Resize OpenStack Instance (Virtual Machine) from Command line.md new file mode 100644 index 0000000000..e235cabdbf --- /dev/null +++ b/sources/tech/20190121 How to Resize OpenStack Instance (Virtual Machine) from Command line.md @@ -0,0 +1,149 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How to Resize OpenStack Instance (Virtual Machine) from Command line) +[#]: via: (https://www.linuxtechi.com/resize-openstack-instance-command-line/) +[#]: author: (Pradeep Kumar http://www.linuxtechi.com/author/pradeep/) + +How to Resize OpenStack Instance (Virtual Machine) from Command line +====== + +Being a Cloud administrator, resizing or changing resources of an instance or virtual machine is one of the most common tasks. + + + +In Openstack environment, there are some scenarios where cloud user has spin a vm using some flavor( like m1.smalll) where root partition disk size is 20 GB, but at some point of time user wants to extends the root partition size to 40 GB. So resizing of vm’s root partition can be accomplished by using the resize option in nova command. During the resize, we need to specify the new flavor that will include disk size as 40 GB. + +**Note:** Once you extend the instance resources like RAM, CPU and disk using resize option in openstack then you can’t reduce it. + +**Read More on** : [**How to Create and Delete Virtual Machine(VM) from Command line in OpenStack**][1] + +In this tutorial I will demonstrate how to resize an openstack instance from command line. Let’s assume I have an existing instance named “ **test_resize_vm** ” and it’s associated flavor is “m1.small” and root partition disk size is 20 GB. + +Execute the below command from controller node to check on which compute host our vm “test_resize_vm” is provisioned and its flavor details + +``` +:~# openstack server show test_resize_vm | grep -E "flavor|hypervisor" +| OS-EXT-SRV-ATTR:hypervisor_hostname | compute-57 | +| flavor | m1.small (2) | +:~# +``` + +Login to VM as well and check the root partition size, + +``` +[[email protected] ~]# df -Th +Filesystem Type Size Used Avail Use% Mounted on +/dev/vda1 xfs 20G 885M 20G 5% / +devtmpfs devtmpfs 900M 0 900M 0% /dev +tmpfs tmpfs 920M 0 920M 0% /dev/shm +tmpfs tmpfs 920M 8.4M 912M 1% /run +tmpfs tmpfs 920M 0 920M 0% /sys/fs/cgroup +tmpfs tmpfs 184M 0 184M 0% /run/user/1000 +[[email protected] ~]# echo "test file for resize operation" > demofile +[[email protected] ~]# cat demofile +test file for resize operation +[[email protected] ~]# +``` + +Get the available flavor list using below command, + +``` +:~# openstack flavor list ++--------------------------------------|-----------------|-------|------|-----------|-------|-----------+ +| ID | Name | RAM | Disk | Ephemeral | VCPUs | Is Public | ++--------------------------------------|-----------------|-------|------|-----------|-------|-----------+ +| 2 | m1.small | 2048 | 20 | 0 | 1 | True | +| 3 | m1.medium | 4096 | 40 | 0 | 2 | True | +| 4 | m1.large | 8192 | 80 | 0 | 4 | True | +| 5 | m1.xlarge | 16384 | 160 | 0 | 8 | True | ++--------------------------------------|-----------------|-------|------|-----------|-------|-----------+ +``` + +So we will be using the flavor “m1.medium” for resize operation, Run the beneath nova command to resize “test_resize_vm”, + +Syntax: # nova resize {VM_Name} {flavor_id} —poll + +``` +:~# nova resize test_resize_vm 3 --poll +Server resizing... 100% complete +Finished +:~# +``` + +Now confirm the resize operation using “ **openstack server –confirm”** command, + +``` +~# openstack server list | grep -i test_resize_vm +| 1d56f37f-94bd-4eef-9ff7-3dccb4682ce0 | test_resize_vm | VERIFY_RESIZE |private-net=10.20.10.51 | +:~# +``` + +As we can see in the above command output the current status of the vm is “ **verify_resize** “, execute below command to confirm resize, + +``` +~# openstack server resize --confirm 1d56f37f-94bd-4eef-9ff7-3dccb4682ce0 +~# +``` + +After the resize confirmation, status of VM will become active, now re-verify hypervisor and flavor details for the vm + +``` +:~# openstack server show test_resize_vm | grep -E "flavor|hypervisor" +| OS-EXT-SRV-ATTR:hypervisor_hostname | compute-58 | +| flavor | m1.medium (3)| +``` + +Login to your VM now and verify the root partition size + +``` +[[email protected] ~]# df -Th +Filesystem Type Size Used Avail Use% Mounted on +/dev/vda1 xfs 40G 887M 40G 3% / +devtmpfs devtmpfs 1.9G 0 1.9G 0% /dev +tmpfs tmpfs 1.9G 0 1.9G 0% /dev/shm +tmpfs tmpfs 1.9G 8.4M 1.9G 1% /run +tmpfs tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup +tmpfs tmpfs 380M 0 380M 0% /run/user/1000 +[[email protected] ~]# cat demofile +test file for resize operation +[[email protected] ~]# +``` + +This confirm that VM root partition has been resized successfully. + +**Note:** Due to some reason if resize operation was not successful and you want to revert the vm back to previous state, then run the following command, + +``` +# openstack server resize --revert {instance_uuid} +``` + +If have noticed “ **openstack server show** ” commands output, VM is migrated from compute-57 to compute-58 after resize. This is the default behavior of “nova resize” command ( i.e nova resize command will migrate the instance to another compute & then resize it based on the flavor details) + +In case if you have only one compute node then nova resize will not work, but we can make it work by changing the below parameter in nova.conf file on compute node, + +Login to compute node, verify the parameter value + +If “ **allow_resize_to_same_host** ” is set as False then change it to True and restart the nova compute service. + +**Read More on** [**OpenStack Deployment using Devstack on CentOS 7 / RHEL 7 System**][2] + +That’s all from this tutorial, in case it helps you technically then please do share your feedback and comments. + +-------------------------------------------------------------------------------- + +via: https://www.linuxtechi.com/resize-openstack-instance-command-line/ + +作者：[Pradeep Kumar][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: http://www.linuxtechi.com/author/pradeep/ +[b]: https://github.com/lujun9972 +[1]: https://www.linuxtechi.com/create-delete-virtual-machine-command-line-openstack/ +[2]: https://www.linuxtechi.com/openstack-deployment-devstack-centos-7-rhel-7/ diff --git a/sources/tech/20190122 Dcp (Dat Copy) - Easy And Secure Way To Transfer Files Between Linux Systems.md b/sources/tech/20190122 Dcp (Dat Copy) - Easy And Secure Way To Transfer Files Between Linux Systems.md new file mode 100644 index 0000000000..b6499932ae --- /dev/null +++ b/sources/tech/20190122 Dcp (Dat Copy) - Easy And Secure Way To Transfer Files Between Linux Systems.md @@ -0,0 +1,177 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Dcp (Dat Copy) – Easy And Secure Way To Transfer Files Between Linux Systems) +[#]: via: (https://www.2daygeek.com/dcp-dat-copy-secure-way-to-transfer-files-between-linux-systems/) +[#]: author: (Vinoth Kumar https://www.2daygeek.com/author/vinoth/) + +Dcp (Dat Copy) – Easy And Secure Way To Transfer Files Between Linux Systems +====== + +Linux has native command to perform this task nicely using scp and rsync. However, we need to try new things. + +Also, we need to encourage the developers who is working new things with different concept and new technology. + +We also written few articles about these kind of topic, you can navigate those by clicking the below appropriate links. + +Those are **[OnionShare][1]** , **[Magic Wormhole][2]** , **[Transfer.sh][3]** and **ffsend**. + +### What’s Dcp? + +[dcp][4] copies files between hosts on a network using the peer-to-peer Dat network. + +dcp can be seen as an alternative to tools like scp, removing the need to configure SSH access between hosts. + +This lets you transfer files between two remote hosts, without you needing to worry about the specifics of how said hosts reach each other and regardless of whether hosts are behind NATs. + +dcp requires zero configuration and is secure, fast, and peer-to-peer. Also, this is not production-ready software. Use at your own risk. + +### What’s Dat Protocol? + +Dat is a peer-to-peer protocol. A community-driven project powering a next-generation Web. + +### How dcp works: + +dcp will create a dat archive for a specified set of files or directories and, using the generated public key, lets you download said archive from a second host. + +Any data shared over the network is encrypted using the public key of the archive, meaning data access is limited to those who have access to said key. + +### dcp Use cases: + + * Send files to multiple colleagues – just send the generated public key via chat and they can receive the files on their machine. + * Sync files between two physical computers on your local network, without needing to set up SSH access. + * Easily send files to a friend without needing to create a zip and upload it the cloud. + * Copy files to a remote server when you have shell access but not SSH, for example on a kubernetes pod. + * Share files between Linux/macOS and Windows, which isn’t exactly known for great SSH support. + + + +### How To Install NodeJS & npm in Linux? + +dcp package was written in JavaScript programming language so, we need to install NodeJS as a prerequisites to install dcp. Use the following command to install NodeJS in Linux. + +For **`Fedora`** system, use **[DNF Command][5]** to install NodeJS & npm. + +``` +$ sudo dnf install nodejs npm +``` + +For **`Debian/Ubuntu`** systems, use **[APT-GET Command][6]** or **[APT Command][7]** to install NodeJS & npm. + +``` +$ sudo apt install nodejs npm +``` + +For **`Arch Linux`** based systems, use **[Pacman Command][8]** to install NodeJS & npm. + +``` +$ sudo pacman -S nodejs npm +``` + +For **`RHEL/CentOS`** systems, use **[YUM Command][9]** to install NodeJS & npm. + +``` +$ sudo yum install epel-release +$ sudo yum install nodejs npm +``` + +For **`openSUSE Leap`** system, use **[Zypper Command][10]** to install NodeJS & npm. + +``` +$ sudo zypper nodejs6 +``` + +### How To Install dcp in Linux? + +Once you have installed the NodeJS, use the following npm command to install dcp. + +npm is a package manager for the JavaScript programming language. It is the default package manager for the JavaScript runtime environment Node.js. + +``` +# npm i -g dat-cp +``` + +### How to Send Files Through dcp? + +Enter the files or folders which you want to transfer to remote server followed by the dcp command, And no need to mention the destination machine name. + +``` +# dcp [File Name Which You Want To Transfer] +``` + +It will generate a dat archive for the given file when you ran the dcp command. Once it’s done then it will geerate a public key at the bottom of the page. + +### How To Receive Files Through dcp? + +Enter the generated the public key on remote server to receive the files or folders. + +``` +# dcp [Public Key] +``` + +To recursively copy directories. + +``` +# dcp [Folder Name Which You Want To Transfer] -r +``` + +In the following example, we are going to transfer a single file. +![][12] + +Output for the above file transfer. +![][13] + +If you want to send more than one file, use the following format. +![][14] + +Output for the above file transfer. +![][15] + +To recursively copy directories. +![][16] + +Output for the above folder transfer. +![][17] + +It won’t allow you to download the files or folders in second time. It means once you downloaded the files or folders then immediately the link will be expired. +![][18] + +Navigate to man page to know about other options. + +``` +# dcp --help +``` + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/dcp-dat-copy-secure-way-to-transfer-files-between-linux-systems/ + +作者：[Vinoth Kumar][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.2daygeek.com/author/vinoth/ +[b]: https://github.com/lujun9972 +[1]: https://www.2daygeek.com/onionshare-secure-way-to-share-files-sharing-tool-linux/ +[2]: https://www.2daygeek.com/wormhole-securely-share-files-from-linux-command-line/ +[3]: https://www.2daygeek.com/transfer-sh-easy-fast-way-share-files-over-internet-from-command-line/ +[4]: https://github.com/tom-james-watson/dat-cp +[5]: https://www.2daygeek.com/dnf-command-examples-manage-packages-fedora-system/ +[6]: https://www.2daygeek.com/apt-get-apt-cache-command-examples-manage-packages-debian-ubuntu-systems/ +[7]: https://www.2daygeek.com/apt-command-examples-manage-packages-debian-ubuntu-systems/ +[8]: https://www.2daygeek.com/pacman-command-examples-manage-packages-arch-linux-system/ +[9]: https://www.2daygeek.com/yum-command-examples-manage-packages-rhel-centos-systems/ +[10]: https://www.2daygeek.com/zypper-command-examples-manage-packages-opensuse-system/ +[11]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[12]: https://www.2daygeek.com/wp-content/uploads/2019/01/Dcp-Dat-Copy-Easy-And-Secure-Way-To-Transfer-Files-Between-Linux-Systems-1.png +[13]: https://www.2daygeek.com/wp-content/uploads/2019/01/Dcp-Dat-Copy-Easy-And-Secure-Way-To-Transfer-Files-Between-Linux-Systems-2.png +[14]: https://www.2daygeek.com/wp-content/uploads/2019/01/Dcp-Dat-Copy-Easy-And-Secure-Way-To-Transfer-Files-Between-Linux-Systems-3.jpg +[15]: https://www.2daygeek.com/wp-content/uploads/2019/01/Dcp-Dat-Copy-Easy-And-Secure-Way-To-Transfer-Files-Between-Linux-Systems-4.jpg +[16]: https://www.2daygeek.com/wp-content/uploads/2019/01/Dcp-Dat-Copy-Easy-And-Secure-Way-To-Transfer-Files-Between-Linux-Systems-6.jpg +[17]: https://www.2daygeek.com/wp-content/uploads/2019/01/Dcp-Dat-Copy-Easy-And-Secure-Way-To-Transfer-Files-Between-Linux-Systems-7.jpg +[18]: https://www.2daygeek.com/wp-content/uploads/2019/01/Dcp-Dat-Copy-Easy-And-Secure-Way-To-Transfer-Files-Between-Linux-Systems-5.jpg diff --git a/sources/tech/20190122 Get started with Go For It, a flexible to-do list application.md b/sources/tech/20190122 Get started with Go For It, a flexible to-do list application.md new file mode 100644 index 0000000000..56dde41884 --- /dev/null +++ b/sources/tech/20190122 Get started with Go For It, a flexible to-do list application.md @@ -0,0 +1,60 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Get started with Go For It, a flexible to-do list application) +[#]: via: (https://opensource.com/article/19/1/productivity-tool-go-for-it) +[#]: author: (Kevin Sonney https://opensource.com/users/ksonney (Kevin Sonney)) + +Get started with Go For It, a flexible to-do list application +====== +Go For It, the tenth in our series on open source tools that will make you more productive in 2019, builds on the Todo.txt system to help you get more things done. + + +There seems to be a mad rush at the beginning of every year to find ways to be more productive. New Year's resolutions, the itch to start the year off right, and of course, an "out with the old, in with the new" attitude all contribute to this. And the usual round of recommendations is heavily biased towards closed source and proprietary software. It doesn't have to be that way. + +Here's the tenth of my picks for 19 new (or new-to-you) open source tools to help you be more productive in 2019. + +### Go For It + +Sometimes what a person needs to be productive isn't a fancy kanban board or a set of notes, but a simple, straightforward to-do list. Something that is as basic as "add item to list, check it off when done." And for that, the [plain-text Todo.txt system][1] is possibly one of the easiest to use, and it's supported on almost every system out there. + + + +[Go For It][2] is a simple, easy-to-use graphical interface for Todo.txt. It can be used with an existing file, if you are already using Todo.txt, and will create both a to-do and a done file if you aren't. It allows drag-and-drop ordering of tasks, allowing users to organize to-do items in the order they want to execute them. It also supports priorities, projects, and contexts, as outlined in the [Todo.txt format guidelines][3]. And, it can filter tasks by context or project simply by clicking on the project or context in the task list. + + + +At first, Go For It may look the same as just about any other Todo.txt program, but looks can be deceiving. The real feature that sets Go For It apart is that it includes a built-in [Pomodoro Technique][4] timer. Select the task you want to complete, switch to the Timer tab, and click Start. When the task is done, simply click Done, and it will automatically reset the timer and pick the next task on the list. You can pause and restart the timer as well as click Skip to jump to the next task (or break). It provides a warning when 60 seconds are left for the current task. The default time for tasks is set at 25 minutes, and the default time for breaks is set at five minutes. You can adjust this in the Settings screen, as well as the location of the directory containing your Todo.txt and done.txt files. + + + +Go For It's third tab, Done, allows you to look at the tasks you've completed and clean them out when you want. Being able to look at what you've accomplished can be very motivating and a good way to get a feel for where you are in a longer process. + + + +It also has all of Todo.txt's other advantages. Go For It's list is accessible by other programs that use the same format, including [Todo.txt's original command-line tool][5] and any [add-ons][6] you've installed. + +Go For It seeks to be a simple tool to help manage your to-do list and get those items done. If you already use Todo.txt, Go For It is a fantastic addition to your toolkit, and if you don't, it's a really good way to start using one of the simplest and most flexible systems available. + + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/productivity-tool-go-for-it + +作者：[Kevin Sonney][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/ksonney (Kevin Sonney) +[b]: https://github.com/lujun9972 +[1]: http://todotxt.org/ +[2]: http://manuel-kehl.de/projects/go-for-it/ +[3]: https://github.com/todotxt/todo.txt +[4]: https://en.wikipedia.org/wiki/Pomodoro_Technique +[5]: https://github.com/todotxt/todo.txt-cli +[6]: https://github.com/todotxt/todo.txt-cli/wiki/Todo.sh-Add-on-Directory diff --git a/sources/tech/20190122 How To Copy A File-Folder From A Local System To Remote System In Linux.md b/sources/tech/20190122 How To Copy A File-Folder From A Local System To Remote System In Linux.md new file mode 100644 index 0000000000..6de6cd173f --- /dev/null +++ b/sources/tech/20190122 How To Copy A File-Folder From A Local System To Remote System In Linux.md @@ -0,0 +1,398 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How To Copy A File/Folder From A Local System To Remote System In Linux?) +[#]: via: (https://www.2daygeek.com/linux-scp-rsync-pscp-command-copy-files-folders-in-multiple-servers-using-shell-script/) +[#]: author: (Prakash Subramanian https://www.2daygeek.com/author/prakash/) + +How To Copy A File/Folder From A Local System To Remote System In Linux? +====== + +Copying a file from one server to another server or local to remote is one of the routine task for Linux administrator. + +If anyone says no, i won’t accept because this is one of the regular activity wherever you go. + +It can be done in many ways and we are trying to cover all the possible options. + +You can choose the one which you would prefer. Also, check other commands as well that may help you for some other purpose. + +I have tested all these commands and script in my test environment so, you can use this for your routine work. + +By default every one go with SCP because it’s one of the native command that everyone use for file copy. But commands which is listed in this article are be smart so, give a try if you would like to try new things. + +This can be done in below four ways easily. + + * **`SCP:`** scp copies files between hosts on a network. It uses ssh for data transfer, and uses the same authentication and provides the same security as ssh. + * **`RSYNC:`** rsync is a fast and extraordinarily versatile file copying tool. It can copy locally, to/from another host over any remote shell, or to/from a remote rsync daemon. + * **`PSCP:`** pscp is a program for copying files in parallel to a number of hosts. It provides features such as passing a password to scp, saving output to files, and timing out. + * **`PRSYNC:`** prsync is a program for copying files in parallel to a number of hosts. It provides features such as passing a password to ssh, saving output to files, and timing out. + + + +### Method-1: Copy Files/Folders From A Local System To Remote System In Linux Using SCP Command? + +scp command allow us to copy files/folders from a local system to remote system. + +We are going to copy the `output.txt` file from my local system to `2g.CentOS.com` remote system under `/opt/backup` directory. + +``` +# scp output.txt root@2g.CentOS.com:/opt/backup + +output.txt 100% 2468 2.4KB/s 00:00 +``` + +We are going to copy two files `output.txt` and `passwd-up.sh` files from my local system to `2g.CentOS.com` remote system under `/opt/backup` directory. + +``` +# scp output.txt passwd-up.sh root@2g.CentOS.com:/opt/backup + +output.txt 100% 2468 2.4KB/s 00:00 +passwd-up.sh 100% 877 0.9KB/s 00:00 +``` + +We are going to copy the `shell-script` directory from my local system to `2g.CentOS.com` remote system under `/opt/backup` directory. + +This will copy the `shell-script` directory and associated files under `/opt/backup` directory. + +``` +# scp -r /home/daygeek/2g/shell-script/ [email protected]:/opt/backup/ + +output.txt 100% 2468 2.4KB/s 00:00 +ovh.sh 100% 76 0.1KB/s 00:00 +passwd-up.sh 100% 877 0.9KB/s 00:00 +passwd-up1.sh 100% 7 0.0KB/s 00:00 +server-list.txt 100% 23 0.0KB/s 00:00 +``` + +### Method-2: Copy Files/Folders From A Local System To Multiple Remote System In Linux Using Shell Script with scp Command? + +If you would like to copy the same file into multiple remote servers then create the following small shell script to achieve this. + +To do so, get the servers list and add those into `server-list.txt` file. Make sure you have to update the servers list into `server-list.txt` file. Each server should be in separate line. + +Finally mention the file location which you want to copy like below. + +``` +# file-copy.sh + +#!/bin/sh +for server in `more server-list.txt` +do + scp /home/daygeek/2g/shell-script/output.txt [email protected]$server:/opt/backup +done +``` + +Once you done, set an executable permission to password-update.sh file. + +``` +# chmod +x file-copy.sh +``` + +Finally run the script to achieve this. + +``` +# ./file-copy.sh + +output.txt 100% 2468 2.4KB/s 00:00 +output.txt 100% 2468 2.4KB/s 00:00 +``` + +Use the following script to copy the multiple files into multiple remote servers. + +``` +# file-copy.sh + +#!/bin/sh +for server in `more server-list.txt` +do + scp /home/daygeek/2g/shell-script/output.txt passwd-up.sh [email protected]$server:/opt/backup +done +``` + +The below output shows all the files twice as this copied into two servers. + +``` +# ./file-cp.sh + +output.txt 100% 2468 2.4KB/s 00:00 +passwd-up.sh 100% 877 0.9KB/s 00:00 +output.txt 100% 2468 2.4KB/s 00:00 +passwd-up.sh 100% 877 0.9KB/s 00:00 +``` + +Use the following script to copy the directory recursively into multiple remote servers. + +``` +# file-copy.sh + +#!/bin/sh +for server in `more server-list.txt` +do + scp -r /home/daygeek/2g/shell-script/ [email protected]$server:/opt/backup +done +``` + +Output for the above script. + +``` +# ./file-cp.sh + +output.txt 100% 2468 2.4KB/s 00:00 +ovh.sh 100% 76 0.1KB/s 00:00 +passwd-up.sh 100% 877 0.9KB/s 00:00 +passwd-up1.sh 100% 7 0.0KB/s 00:00 +server-list.txt 100% 23 0.0KB/s 00:00 + +output.txt 100% 2468 2.4KB/s 00:00 +ovh.sh 100% 76 0.1KB/s 00:00 +passwd-up.sh 100% 877 0.9KB/s 00:00 +passwd-up1.sh 100% 7 0.0KB/s 00:00 +server-list.txt 100% 23 0.0KB/s 00:00 +``` + +### Method-3: Copy Files/Folders From A Local System To Multiple Remote System In Linux Using PSCP Command? + +pscp command directly allow us to perform the copy to multiple remote servers. + +Use the following pscp command to copy a single file to remote server. + +``` +# pscp.pssh -H 2g.CentOS.com /home/daygeek/2g/shell-script/output.txt /opt/backup + +[1] 18:46:11 [SUCCESS] 2g.CentOS.com +``` + +Use the following pscp command to copy a multiple files to remote server. + +``` +# pscp.pssh -H 2g.CentOS.com /home/daygeek/2g/shell-script/output.txt ovh.sh /opt/backup + +[1] 18:47:48 [SUCCESS] 2g.CentOS.com +``` + +Use the following pscp command to copy a directory recursively to remote server. + +``` +# pscp.pssh -H 2g.CentOS.com -r /home/daygeek/2g/shell-script/ /opt/backup + +[1] 18:48:46 [SUCCESS] 2g.CentOS.com +``` + +Use the following pscp command to copy a single file to multiple remote servers. + +``` +# pscp.pssh -h server-list.txt /home/daygeek/2g/shell-script/output.txt /opt/backup + +[1] 18:49:48 [SUCCESS] 2g.CentOS.com +[2] 18:49:48 [SUCCESS] 2g.Debian.com +``` + +Use the following pscp command to copy a multiple files to multiple remote servers. + +``` +# pscp.pssh -h server-list.txt /home/daygeek/2g/shell-script/output.txt passwd-up.sh /opt/backup + +[1] 18:50:30 [SUCCESS] 2g.Debian.com +[2] 18:50:30 [SUCCESS] 2g.CentOS.com +``` + +Use the following pscp command to copy a directory recursively to multiple remote servers. + +``` +# pscp.pssh -h server-list.txt -r /home/daygeek/2g/shell-script/ /opt/backup + +[1] 18:51:31 [SUCCESS] 2g.Debian.com +[2] 18:51:31 [SUCCESS] 2g.CentOS.com +``` + +### Method-4: Copy Files/Folders From A Local System To Multiple Remote System In Linux Using rsync Command? + +Rsync is a fast and extraordinarily versatile file copying tool. It can copy locally, to/from another host over any remote shell, or to/from a remote rsync daemon. + +Use the following rsync command to copy a single file to remote server. + +``` +# rsync -avz /home/daygeek/2g/shell-script/output.txt [email protected]:/opt/backup + +sending incremental file list +output.txt + +sent 598 bytes received 31 bytes 1258.00 bytes/sec +total size is 2468 speedup is 3.92 +``` + +Use the following pscp command to copy a multiple files to remote server. + +``` +# rsync -avz /home/daygeek/2g/shell-script/output.txt passwd-up.sh root@2g.CentOS.com:/opt/backup + +sending incremental file list +output.txt +passwd-up.sh + +sent 737 bytes received 50 bytes 1574.00 bytes/sec +total size is 2537 speedup is 3.22 +``` + +Use the following rsync command to copy a single file to remote server overh ssh. + +``` +# rsync -avzhe ssh /home/daygeek/2g/shell-script/output.txt root@2g.CentOS.com:/opt/backup + +sending incremental file list +output.txt + +sent 598 bytes received 31 bytes 419.33 bytes/sec +total size is 2.47K speedup is 3.92 +``` + +Use the following pscp command to copy a directory recursively to remote server over ssh. This will copy only files not the base directory. + +``` +# rsync -avzhe ssh /home/daygeek/2g/shell-script/ root@2g.CentOS.com:/opt/backup + +sending incremental file list +./ +output.txt +ovh.sh +passwd-up.sh +passwd-up1.sh +server-list.txt + +sent 3.85K bytes received 281 bytes 8.26K bytes/sec +total size is 9.12K speedup is 2.21 +``` + +### Method-5: Copy Files/Folders From A Local System To Multiple Remote System In Linux Using Shell Script with rsync Command? + +If you would like to copy the same file into multiple remote servers then create the following small shell script to achieve this. + +``` +# file-copy.sh + +#!/bin/sh +for server in `more server-list.txt` +do + rsync -avzhe ssh /home/daygeek/2g/shell-script/ root@2g.CentOS.com$server:/opt/backup +done +``` + +Output for the above shell script. + +``` +# ./file-copy.sh + +sending incremental file list +./ +output.txt +ovh.sh +passwd-up.sh +passwd-up1.sh +server-list.txt + +sent 3.86K bytes received 281 bytes 8.28K bytes/sec +total size is 9.13K speedup is 2.21 + +sending incremental file list +./ +output.txt +ovh.sh +passwd-up.sh +passwd-up1.sh +server-list.txt + +sent 3.86K bytes received 281 bytes 2.76K bytes/sec +total size is 9.13K speedup is 2.21 +``` + +### Method-6: Copy Files/Folders From A Local System To Multiple Remote System In Linux Using Shell Script with scp Command? + +In the above two shell script, we need to mention the file and folder location as a prerequiesties but here i did a small modification that allow the script to get a file or folder as a input. It could be very useful when you want to perform the copy multiple times in a day. + +``` +# file-copy.sh + +#!/bin/sh +for server in `more server-list.txt` +do +scp -r $1 root@2g.CentOS.com$server:/opt/backup +done +``` + +Run the shell script and give the file name as a input. + +``` +# ./file-copy.sh output1.txt + +output1.txt 100% 3558 3.5KB/s 00:00 +output1.txt 100% 3558 3.5KB/s 00:00 +``` + +### Method-7: Copy Files/Folders From A Local System To Multiple Remote System In Linux With Non-Standard Port Number? + +Use the below shell script to copy a file or folder if you are using Non-Standard port. + +If you are using `Non-Standard` port, make sure you have to mention the port number as follow for SCP command. + +``` +# file-copy-scp.sh + +#!/bin/sh +for server in `more server-list.txt` +do +scp -P 2222 -r $1 root@2g.CentOS.com$server:/opt/backup +done +``` + +Run the shell script and give the file name as a input. + +``` +# ./file-copy.sh ovh.sh + +ovh.sh 100% 3558 3.5KB/s 00:00 +ovh.sh 100% 3558 3.5KB/s 00:00 +``` + +If you are using `Non-Standard` port, make sure you have to mention the port number as follow for rsync command. + +``` +# file-copy-rsync.sh + +#!/bin/sh +for server in `more server-list.txt` +do +rsync -avzhe 'ssh -p 2222' $1 root@2g.CentOS.com$server:/opt/backup +done +``` + +Run the shell script and give the file name as a input. + +``` +# ./file-copy-rsync.sh passwd-up.sh +sending incremental file list +passwd-up.sh + +sent 238 bytes received 35 bytes 26.00 bytes/sec +total size is 159 speedup is 0.58 + +sending incremental file list +passwd-up.sh + +sent 238 bytes received 35 bytes 26.00 bytes/sec +total size is 159 speedup is 0.58 +``` +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/linux-scp-rsync-pscp-command-copy-files-folders-in-multiple-servers-using-shell-script/ + +作者：[Prakash Subramanian][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.2daygeek.com/author/prakash/ +[b]: https://github.com/lujun9972 diff --git a/sources/tech/20190123 Dockter- A container image builder for researchers.md b/sources/tech/20190123 Dockter- A container image builder for researchers.md new file mode 100644 index 0000000000..359d0c1d1e --- /dev/null +++ b/sources/tech/20190123 Dockter- A container image builder for researchers.md @@ -0,0 +1,121 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Dockter: A container image builder for researchers) +[#]: via: (https://opensource.com/article/19/1/dockter-image-builder-researchers) +[#]: author: (Nokome Bentley https://opensource.com/users/nokome) + +Dockter: A container image builder for researchers +====== +Dockter supports the specific requirements of researchers doing data analysis, including those using R. + + + +Dependency hell is ubiquitous in the world of software for research, and this affects research transparency and reproducibility. Containerization is one solution to this problem, but it creates new challenges for researchers. Docker is gaining popularity in the research community—but using it efficiently requires solid Dockerfile writing skills. + +As a part of the [Stencila][1] project, which is a platform for creating, collaborating on, and sharing data-driven content, we are developing [Dockter][2], an open source tool that makes it easier for researchers to create Docker images for their projects. Dockter scans a research project's source code, generates a Dockerfile, and builds a Docker image. It has a range of features that allow flexibility and can help researchers learn more about working with Docker. + +Dockter also generates a JSON file with information about the software environment (based on [CodeMeta][3] and [Schema.org][4]) to enable further processing and interoperability with other tools. + +Several other projects create Docker images from source code and/or requirements files, including: [alibaba/derrick][5], [jupyter/repo2docker][6], [Gueils/whales][7], [o2r-project/containerit][8]; [openshift/source-to-image][9], and [ViDA-NYU/reprozip][10]. Dockter is similar to repo2docker, containerit, and ReproZip in that it is aimed at researchers doing data analysis (and supports R), whereas most other tools are aimed at software developers (and don't support R). + +Dockter differs from these projects principally in that it: + + * Performs static code analysis for multiple languages to determine package requirements + * Uses package databases to determine package system dependencies and generate linked metadata (containerit does this for R) + * Installs language package dependencies quicker (which can be useful during research projects where dependencies often change) + * By default but optionally, installs Stencila packages so that Stencila client interfaces can execute code in the container + + + +### Dockter's features + +Following are some of the ways researchers can use Dockter. + +#### Generating Docker images from code + +Dockter scans a research project folder and builds a Docker image for it. If the folder already has a Dockerfile, Dockter will build the image from that. If not, Dockter will scan the source code files in the folder and generate one. Dockter currently handles R, Python, and Node.js source code. The .dockerfile (with the dot at the beginning) it generates is fully editable so users can take over from Dockter and carry on with editing the file as they see fit. + +If the folder contains an R package [DESCRIPTION][11] file, Dockter will install the R packages listed under Imports into the image. If the folder does not contain a DESCRIPTION file, Dockter will scan all the R files in the folder for package import or usage statements and create a .DESCRIPTION file. + +If the folder contains a [requirements.txt][12] file for Python, Dockter will copy it into the Docker image and use [pip][13] to install the specified packages. If the folder does not contain either of those files, Dockter will scan all the folder's .py files for import statements and create a .requirements.txt file. + +If the folder contains a [package.json][14] file, Dockter will copy it into the Docker image and use npm to install the specified packages. If the folder does not contain a package.json file, Dockter will scan all the folder's .js files for require calls and create a .package.json file. + +#### Capturing system requirements automatically + +One of the headaches researchers face when hand-writing Dockerfiles is figuring out which system dependencies their project needs. Often this involves a lot of trial and error. Dockter automatically checks if any dependencies (or dependencies of dependencies, or dependencies of…) require system packages and installs those into the image. No more trial and error cycles of build, fail, add dependency, repeat… + +#### Reinstalling language packages faster + +If you have ever built a Docker image, you know it can be frustrating waiting for all your project's dependencies to reinstall when you add or remove just one. + +This happens because of Docker's layered filesystem: When you update a requirements file, Docker throws away all the subsequent layers—including the one where you previously installed your dependencies. That means all the packages have to be reinstalled. + +Dockter takes a different approach. It leaves the installation of language packages to the language package managers: Python's pip, Node.js's npm, and R's install.packages. These package managers are good at the job they were designed for: checking which packages need to be updated and updating only them. The result is much faster rebuilds, especially for R packages, which often involve compilation. + +Dockter does this by looking for a special **# dockter** comment in a Dockerfile. Instead of throwing away layers, it executes all instructions after this comment in the same layer—thereby reusing packages that were previously installed. + +#### Generating structured metadata for a project + +Dockter uses [JSON-LD][15] as its internal data structure. When it parses a project's source code, it generates a JSON-LD tree using vocabularies from schema.org and CodeMeta. + +Dockter also fetches metadata on a project's dependencies, which could be used to generate a complete software citation for the project. + +### Easy to pick up, easy to throw away + +Dockter is designed to make it easier to get started creating Docker images for your project. But it's also designed to not get in your way or restrict you from using bare Docker. You can easily and individually override any of the steps Dockter takes to build an image. + + * **Code analysis:** To stop Dockter from doing code analysis and specify your project's package dependencies, just remove the leading **.** (dot) from the .DESCRIPTION, .requirements.txt, or .package.json files. + + * **Dockerfile generation:** Dockter aims to generate readable Dockerfiles that conform to best practices. They include comments on what each section does and are a good way to start learning how to write your own Dockerfiles. To stop Dockter from generating a .Dockerfile and start editing it yourself, just rename it Dockerfile (without the leading dot). + + + + +### Install Dockter + +[Dockter is available][16] as pre-compiled, standalone command line tool or as a Node.js package. Click [here][17] for a demo. + +We welcome and encourage all [contributions][18]! + +A longer version of this article is available on the project's [GitHub page][19]. + +Aleksandra Pawlik will present [Building reproducible computing environments: a workshop for non-experts][20] at [linux.conf.au][21], January 21-25 in Christchurch, New Zealand. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/dockter-image-builder-researchers + +作者：[Nokome Bentley][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/nokome +[b]: https://github.com/lujun9972 +[1]: https://stenci.la/ +[2]: https://stencila.github.io/dockter/ +[3]: https://codemeta.github.io/index.html +[4]: http://Schema.org +[5]: https://github.com/alibaba/derrick +[6]: https://github.com/jupyter/repo2docker +[7]: https://github.com/Gueils/whales +[8]: https://github.com/o2r-project/containerit +[9]: https://github.com/openshift/source-to-image +[10]: https://github.com/ViDA-NYU/reprozip +[11]: http://r-pkgs.had.co.nz/description.html +[12]: https://pip.readthedocs.io/en/1.1/requirements.html +[13]: https://pypi.org/project/pip/ +[14]: https://docs.npmjs.com/files/package.json +[15]: https://json-ld.org/ +[16]: https://github.com/stencila/dockter/releases/ +[17]: https://asciinema.org/a/pOHpxUqIVkGdA1dqu7bENyxZk?size=medium&cols=120&autoplay=1 +[18]: https://github.com/stencila/dockter/blob/master/CONTRIBUTING.md +[19]: https://github.com/stencila/dockter +[20]: https://2019.linux.conf.au/schedule/presentation/185/ +[21]: https://linux.conf.au/ diff --git a/sources/tech/20190123 GStreamer WebRTC- A flexible solution to web-based media.md b/sources/tech/20190123 GStreamer WebRTC- A flexible solution to web-based media.md new file mode 100644 index 0000000000..bb7e129ff3 --- /dev/null +++ b/sources/tech/20190123 GStreamer WebRTC- A flexible solution to web-based media.md @@ -0,0 +1,108 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (GStreamer WebRTC: A flexible solution to web-based media) +[#]: via: (https://opensource.com/article/19/1/gstreamer) +[#]: author: (Nirbheek Chauhan https://opensource.com/users/nirbheek) + +GStreamer WebRTC: A flexible solution to web-based media +====== +GStreamer's WebRTC implementation eliminates some of the shortcomings of using WebRTC in native apps, server applications, and IoT devices. + + + +Currently, [WebRTC.org][1] is the most popular and feature-rich WebRTC implementation. It is used in Chrome and Firefox and works well for browsers, but the Native API and implementation have several shortcomings that make it a less-than-ideal choice for uses outside of browsers, including native apps, server applications, and internet of things (IoT) devices. + +Last year, our company ([Centricular][2]) made an independent implementation of a Native WebRTC API available in GStreamer 1.14. This implementation is much easier to use and more flexible than the WebRTC.org Native API, is transparently compatible with WebRTC.org, has been tested with all browsers, and is already in production use. + +### What are GStreamer and WebRTC? + +[GStreamer][3] is an open source, cross-platform multimedia framework and one of the easiest and most flexible ways to implement any application that needs to play, record, or transform media-like data across a diverse scale of devices and products, including embedded (IoT, in-vehicle infotainment, phones, TVs, etc.), desktop (video/music players, video recording, non-linear editing, video conferencing, [VoIP][4] clients, browsers, etc.), servers (encode/transcode farms, video/voice conferencing servers, etc.), and [more][5]. + +The main feature that makes GStreamer the go-to multimedia framework for many people is its pipeline-based model, which solves one of the hardest problems in API design: catering to applications of varying complexity; from the simplest one-liners and quick solutions to those that need several hundreds of thousands of lines of code to implement their full feature set. If you want to learn how to use GStreamer, [Jan Schmidt's tutorial][6] from [LCA 2018][7] is a good place to start. + +[WebRTC][8] is a set of draft specifications that build upon existing [RTP][9], [RTCP][10], [SDP][11], [DTLS][12], [ICE][13], and other real-time communication (RTC) specifications and define an API for making them accessible using browser JavaScript (JS) APIs. + +People have been doing real-time communication over [IP][14] for [decades][15] with the protocols WebRTC builds upon. WebRTC's real innovation was creating a bridge between native applications and web apps by defining a standard yet flexible API that browsers can expose to untrusted JavaScript code. + +These specifications are [constantly being improved][16], which, combined with the ubiquitous nature of browsers, means WebRTC is fast becoming the standard choice for video conferencing on all platforms and for most applications. + +### **Everything is great, let's build amazing apps!** + +Not so fast, there's more to the story! For web apps, the [PeerConnection API][17] is [everywhere][18]. There are some browser-specific quirks, and the API keeps changing, but the [WebRTC JS adapter][19] handles most of that. Overall, the web app experience is mostly 👍. + +Unfortunately, for native code or applications that need more flexibility than a sandboxed JavaScript app can achieve, there haven't been a lot of great options. + +[Libwebrtc][20] (Google's implementation), [Janus][21], [Kurento][22], and [OpenWebRTC][23] have traditionally been the main contenders, but each implementation has its own inflexibilities, shortcomings, and constraints. + +Libwebrtc is still the most mature implementation, but it is also the most difficult to work with. Since it's embedded inside Chrome, it's a moving target and the project [is quite difficult to build and integrate][24]. These are all obstacles for native or server app developers trying to quickly prototype and experiment with things. + +Also, WebRTC was not built for multimedia, so the lower layers get in the way of non-browser use cases and applications. It is quite painful to do anything other than the default "set raw media, transmit" and "receive from remote, get raw media." This means if you want to use your own filters or hardware-specific codecs or sinks/sources, you end up having to fork libwebrtc. + +[**OpenWebRTC**][23] by Ericsson was the first attempt to rectify this situation. It was built on top of GStreamer. Its target audience was app developers, and it fit the bill quite well as a proof of concept—even though it used a custom API and some of the architectural decisions made it quite inflexible for most other uses. However, after an initial flurry of activity around the project, momentum petered out, the project failed to gather a community, and it is now effectively dead. Full disclosure: Centricular worked with Ericsson to polish some of the rough edges around the project immediately prior to its public release. + +### WebRTC in GStreamer + +GStreamer's WebRTC implementation gives you full control, as it does with any other [GStreamer pipeline][25]. + +As we said, the WebRTC standards build upon existing standards and protocols that serve similar purposes. GStreamer has supported almost all of them for a while now because they were being used for real-time communication, live streaming, and many other IP-based applications. This led Ericsson to choose GStreamer as the base for its OpenWebRTC project. + +Combined with the [SRTP][26] and DTLS plugins that were written during OpenWebRTC's development, it means that the implementation is built upon a solid and well-tested base, and implementing WebRTC features does not involve as much code-from-scratch work as one might presume. However, WebRTC is a large collection of standards, and reaching feature-parity with libwebrtc is an ongoing task. + +Due to decisions made while architecting WebRTCbin's internals, the API follows the PeerConnection specification quite closely. Therefore, almost all its missing features involve writing code that would plug into clearly defined sockets. For instance, since the GStreamer 1.14 release, the following features have been added to the WebRTC implementation and will be available in the next release of the GStreamer WebRTC: + + * Forward error correction + * RTP retransmission (RTX) + * RTP BUNDLE + * Data channels over SCTP + + + +We believe GStreamer's API is the most flexible, versatile, and easy to use WebRTC implementation out there, and it will only get better as time goes by. Bringing the power of pipeline-based multimedia manipulation to WebRTC opens new doors for interesting, unique, and highly efficient applications. If you'd like to demo the technology and play with the code, build and run [these demos][27], which include C, Rust, Python, and C# examples. + +Matthew Waters will present [GStreamer WebRTC—The flexible solution to web-based media][28] at [linux.conf.au][29], January 21-25 in Christchurch, New Zealand. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/gstreamer + +作者：[Nirbheek Chauhan][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/nirbheek +[b]: https://github.com/lujun9972 +[1]: http://webrtc.org/ +[2]: https://www.centricular.com/ +[3]: https://gstreamer.freedesktop.org/documentation/application-development/introduction/gstreamer.html +[4]: https://en.wikipedia.org/wiki/Voice_over_IP +[5]: https://wiki.ligo.org/DASWG/GstLAL +[6]: https://www.youtube.com/watch?v=ZphadMGufY8 +[7]: http://lca2018.linux.org.au/ +[8]: https://en.wikipedia.org/wiki/WebRTC +[9]: https://en.wikipedia.org/wiki/Real-time_Transport_Protocol +[10]: https://en.wikipedia.org/wiki/RTP_Control_Protocol +[11]: https://en.wikipedia.org/wiki/Session_Description_Protocol +[12]: https://en.wikipedia.org/wiki/Datagram_Transport_Layer_Security +[13]: https://en.wikipedia.org/wiki/Interactive_Connectivity_Establishment +[14]: https://en.wikipedia.org/wiki/Internet_Protocol +[15]: https://en.wikipedia.org/wiki/Session_Initiation_Protocol +[16]: https://datatracker.ietf.org/wg/rtcweb/documents/ +[17]: https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection +[18]: https://caniuse.com/#feat=rtcpeerconnection +[19]: https://github.com/webrtc/adapter +[20]: https://github.com/aisouard/libwebrtc +[21]: https://janus.conf.meetecho.com/ +[22]: https://www.kurento.org/kurento-architecture +[23]: https://en.wikipedia.org/wiki/OpenWebRTC +[24]: https://webrtchacks.com/building-webrtc-from-source/ +[25]: https://gstreamer.freedesktop.org/documentation/application-development/introduction/basics.html +[26]: https://en.wikipedia.org/wiki/Secure_Real-time_Transport_Protocol +[27]: https://github.com/centricular/gstwebrtc-demos/ +[28]: https://linux.conf.au/schedule/presentation/143/ +[29]: https://linux.conf.au/ diff --git a/sources/tech/20190123 Mind map yourself using FreeMind and Fedora.md b/sources/tech/20190123 Mind map yourself using FreeMind and Fedora.md new file mode 100644 index 0000000000..146f95752a --- /dev/null +++ b/sources/tech/20190123 Mind map yourself using FreeMind and Fedora.md @@ -0,0 +1,81 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Mind map yourself using FreeMind and Fedora) +[#]: via: (https://fedoramagazine.org/mind-map-yourself-using-freemind-and-fedora/) +[#]: author: (Paul W. Frields https://fedoramagazine.org/author/pfrields/) + +Mind map yourself using FreeMind and Fedora +====== + + +A mind map of yourself sounds a little far-fetched at first. Is this process about neural pathways? Or telepathic communication? Not at all. Instead, a mind map of yourself is a way to describe yourself to others visually. It also shows connections among the characteristics you use to describe yourself. It’s a useful way to share information with others in a clever but also controllable way. You can use any mind map application for this purpose. This article shows you how to get started using [FreeMind][1], available in Fedora. + +### Get the application + +The FreeMind application has been around a while. While the UI is a bit dated and could use a refresh, it’s a powerful app that offers many options for building mind maps. And of course it’s 100% open source. There are other mind mapping apps available for Fedora and Linux users, as well. Check out [this previous article that covers several mind map options][2]. + +Install FreeMind from the Fedora repositories using the Software app if you’re running Fedora Workstation. Or use this [sudo][3] command in a terminal: + +``` +$ sudo dnf install freemind +``` + +You can launch the app from the GNOME Shell Overview in Fedora Workstation. Or use the application start service your desktop environment provides. FreeMind shows you a new, blank map by default: + +![][4] +FreeMind initial (blank) mind map + +A map consists of linked items or descriptions — nodes. When you think of something related to a node you want to capture, simply create a new node connected to it. + +### Mapping yourself + +Click in the initial node. Replace it with your name by editing the text and hitting **Enter**. You’ve just started your mind map. + +What would you think of if you had to fully describe yourself to someone? There are probably many things to cover. How do you spend your time? What do you enjoy? What do you dislike? What do you value? Do you have a family? All of this can be captured in nodes. + +To add a node connection, select the existing node, and hit **Insert** , or use the “light bulb” icon for a new child node. To add another node at the same level as the new child, use **Enter**. + +Don’t worry if you make a mistake. You can use the **Delete** key to remove an unwanted node. There’s no rules about content. Short nodes are best, though. They allow your mind to move quickly when creating the map. Concise nodes also let viewers scan and understand the map easily later. + +This example uses nodes to explore each of these major categories: + +![][5] +Personal mind map, first level + +You could do another round of iteration for each of these areas. Let your mind freely connect ideas to generate the map. Don’t worry about “getting it right.” It’s better to get everything out of your head and onto the display. Here’s what a next-level map might look like. + +![][6] +Personal mind map, second level + +You could expand on any of these nodes in the same way. Notice how much information you can quickly understand about John Q. Public in the example. + +### How to use your personal mind map + +This is a great way to have team or project members introduce themselves to each other. You can apply all sorts of formatting and color to the map to give it personality. These are fun to do on paper, of course. But having one on your Fedora system means you can always fix mistakes, or even make changes as you change. + +Have fun exploring your personal mind map! + + + +-------------------------------------------------------------------------------- + +via: https://fedoramagazine.org/mind-map-yourself-using-freemind-and-fedora/ + +作者：[Paul W. Frields][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://fedoramagazine.org/author/pfrields/ +[b]: https://github.com/lujun9972 +[1]: http://freemind.sourceforge.net/wiki/index.php/Main_Page +[2]: https://fedoramagazine.org/three-mind-mapping-tools-fedora/ +[3]: https://fedoramagazine.org/howto-use-sudo/ +[4]: https://fedoramagazine.org/wp-content/uploads/2019/01/Screenshot-from-2019-01-19-15-17-04-1024x736.png +[5]: https://fedoramagazine.org/wp-content/uploads/2019/01/Screenshot-from-2019-01-19-15-32-38-1024x736.png +[6]: https://fedoramagazine.org/wp-content/uploads/2019/01/Screenshot-from-2019-01-19-15-38-00-1024x736.png diff --git a/sources/tech/20190124 ODrive (Open Drive) - Google Drive GUI Client For Linux.md b/sources/tech/20190124 ODrive (Open Drive) - Google Drive GUI Client For Linux.md new file mode 100644 index 0000000000..71a91ec3d8 --- /dev/null +++ b/sources/tech/20190124 ODrive (Open Drive) - Google Drive GUI Client For Linux.md @@ -0,0 +1,127 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (ODrive (Open Drive) – Google Drive GUI Client For Linux) +[#]: via: (https://www.2daygeek.com/odrive-open-drive-google-drive-gui-client-for-linux/) +[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/) + +ODrive (Open Drive) – Google Drive GUI Client For Linux +====== + +This we had discussed in so many times. However, i will give a small introduction about it. + +As of now there is no official Google Drive Client for Linux and we need to use unofficial clients. + +There are many applications available in Linux for Google Drive integration. + +Each application has came out with set of features. + +We had written few articles about this in our website in the past. + +Those are **[DriveSync][1]** , **[Google Drive Ocamlfuse Client][2]** and **[Mount Google Drive in Linux Using Nautilus File Manager][3]**. + +Today also we are going to discuss about the same topic and the utility name is ODrive. + +### What’s ODrive? + +ODrive stands for Open Drive. It’s a GUI client for Google Drive which was written in electron framework. + +It’s simple GUI which allow users to integrate the Google Drive with few steps. + +### How To Install & Setup ODrive on Linux? + +Since the developer is offering the AppImage package and there is no difficulty for installing the ODrive on Linux. + +Simple download the latest ODrive AppImage package from developer github page using **wget Command**. + +``` +$ wget https://github.com/liberodark/ODrive/releases/download/0.1.3/odrive-0.1.3-x86_64.AppImage +``` + +You have to set executable file permission to the ODrive AppImage file. + +``` +$ chmod +x odrive-0.1.3-x86_64.AppImage +``` + +Simple run the following ODrive AppImage file to launch the ODrive GUI for further setup. + +``` +$ ./odrive-0.1.3-x86_64.AppImage +``` + +You might get the same window like below when you ran the above command. Just hit the **`Next`** button for further setup. +![][5] + +Click **`Connect`** link to add a Google drive account. +![][6] + +Enter your email id which you want to setup a Google Drive account. +![][7] + +Enter your password for the given email id. +![][8] + +Allow ODrive (Open Drive) to access your Google account. +![][9] + +By default, it will choose the folder location. You can change if you want to use the specific one. +![][10] + +Finally hit **`Synchronize`** button to start download the files from Google Drive to your local system. +![][11] + +Synchronizing is in progress. +![][12] + +Once synchronizing is completed. It will show you all files downloaded. +Once synchronizing is completed. It’s shows you that all the files has been downloaded. +![][13] + +I have seen all the files were downloaded in the mentioned directory. +![][14] + +If you want to sync any new files from local system to Google Drive. Just start the `ODrive` from the application menu but it won’t actual launch the application. But it will be running in the background that we can able to see by using the ps command. + +``` +$ ps -df | grep odrive +``` + +![][15] + +It will automatically sync once you add a new file into the google drive folder. The same has been checked through notification menu. Yes, i can see one file was synced to Google Drive. +![][16] + +GUI is not loading after sync, and i’m not sure this functionality. I will check with developer and will add update based on his input. + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/odrive-open-drive-google-drive-gui-client-for-linux/ + +作者：[Magesh Maruthamuthu][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://www.2daygeek.com/author/magesh/ +[b]: https://github.com/lujun9972 +[1]: https://www.2daygeek.com/drivesync-google-drive-sync-client-for-linux/ +[2]: https://www.2daygeek.com/mount-access-google-drive-on-linux-with-google-drive-ocamlfuse-client/ +[3]: https://www.2daygeek.com/mount-access-setup-google-drive-in-linux/ +[4]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[5]: https://www.2daygeek.com/wp-content/uploads/2019/01/odrive-open-drive-google-drive-gui-client-for-linux-1.png +[6]: https://www.2daygeek.com/wp-content/uploads/2019/01/odrive-open-drive-google-drive-gui-client-for-linux-2.png +[7]: https://www.2daygeek.com/wp-content/uploads/2019/01/odrive-open-drive-google-drive-gui-client-for-linux-3.png +[8]: https://www.2daygeek.com/wp-content/uploads/2019/01/odrive-open-drive-google-drive-gui-client-for-linux-4.png +[9]: https://www.2daygeek.com/wp-content/uploads/2019/01/odrive-open-drive-google-drive-gui-client-for-linux-5.png +[10]: https://www.2daygeek.com/wp-content/uploads/2019/01/odrive-open-drive-google-drive-gui-client-for-linux-6.png +[11]: https://www.2daygeek.com/wp-content/uploads/2019/01/odrive-open-drive-google-drive-gui-client-for-linux-7.png +[12]: https://www.2daygeek.com/wp-content/uploads/2019/01/odrive-open-drive-google-drive-gui-client-for-linux-8a.png +[13]: https://www.2daygeek.com/wp-content/uploads/2019/01/odrive-open-drive-google-drive-gui-client-for-linux-9.png +[14]: https://www.2daygeek.com/wp-content/uploads/2019/01/odrive-open-drive-google-drive-gui-client-for-linux-11.png +[15]: https://www.2daygeek.com/wp-content/uploads/2019/01/odrive-open-drive-google-drive-gui-client-for-linux-9b.png +[16]: https://www.2daygeek.com/wp-content/uploads/2019/01/odrive-open-drive-google-drive-gui-client-for-linux-10.png diff --git a/sources/tech/20190124 Orpie- A command-line reverse Polish notation calculator.md b/sources/tech/20190124 Orpie- A command-line reverse Polish notation calculator.md new file mode 100644 index 0000000000..10e666f625 --- /dev/null +++ b/sources/tech/20190124 Orpie- A command-line reverse Polish notation calculator.md @@ -0,0 +1,128 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Orpie: A command-line reverse Polish notation calculator) +[#]: via: (https://opensource.com/article/19/1/orpie) +[#]: author: (Peter Faller https://opensource.com/users/peterfaller) + +Orpie: A command-line reverse Polish notation calculator +====== +Orpie is a scientific calculator that functions much like early, well-loved HP calculators. + +Orpie is a text-mode [reverse Polish notation][1] (RPN) calculator for the Linux console. It works very much like the early, well-loved Hewlett-Packard calculators. + +### Installing Orpie + +RPM and DEB packages are available for most distributions, so installation is just a matter of using either: + +``` +$ sudo apt install orpie +``` + +or + +``` +$ sudo yum install orpie +``` + +Orpie has a comprehensive man page; new users may want to have it open in another terminal window as they get started. Orpie can be customized for each user by editing the **~/.orpierc** configuration file. The [orpierc(5)][2] man page describes the contents of this file, and **/etc/orpierc** describes the default configuration. + +### Starting up + +Start Orpie by typing **orpie** at the command line. The main screen shows context-sensitive help on the left and the stack on the right. The cursor, where you enter numbers you want to calculate, is at the bottom-right corner. + + + +### Example calculation + +For a simple example, let's calculate the factorial of **5 (2 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated 3 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated 4 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated 5)**. First the long way: + +| Keys | Result | +| --------- | --------- | +| 2 | Push 2 onto the stack | +| 3 | Push 3 onto the stack | +| * | Multiply to get 6 | +| 4
- ` 和 `
` 元素那样定义 `
- ` 元素的宽度。这是因为 `
- ` 是 `
` 的子节点，`
` 已经被约束到 550px，所以 `
- ` 不会超出这个范围。
+
+让我们保存文件并刷新浏览器以查看结果：
+
+
+
+你会立即注意到在每个列表项之前显示了重点标志。我们现在不需要在每个列表项之前写 “-”。
+
+经过仔细检查，你会注意到最后一行超出 550px 宽度。这是为什么？因为 HTML 不允许 `
- ` 元素出现在 `
` 元素中。让我们将第一行和最后一行放在单独的 `
` 元素中： + +``` +
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+``` + +``` ++ You complete my darkness with your light. I love: +
+``` + +``` +-
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time. +
+``` + +保存并刷新。 + +注意，这次我们还定义了 `- ` 元素的宽度。那是因为我们现在已经将 `
- ` 元素放在了 `
` 元素之外。 + +定义情书中所有元素的宽度会变得很麻烦。我们有一个特定的元素用于此目的：`
` 元素。一个 `
` 元素就是一个通用容器，用于对内容进行分组，以便轻松设置样式。
+
+让我们用 `
` 元素包装整个情书，并为其赋予宽度：550px 。
+
+```
+`、`
+
+```
+
+棒极了，我们的代码现在看起来简洁多了。
+
+### HTML 中的标题
+
+到目前为止，蝙蝠侠对结果很高兴，他希望在情书上标题。他想写一个标题： “Bat Letter”。当然，你已经看到这个名字了，不是吗？:D
+
+你可以使用 `+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
++ You complete my darkness with your light. I love: +
+-
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time. +
+`、``、``、``、`` 和 `` 标签来添加标题，`` 是最大的标题和最主要的标题，`` 是最小的标题。
+
+
+
+让我们在第二段之前使用 `` 做主标题和一个副标题：
+
+```
+
+ Bat Letter
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+保存，刷新。
+
+
+
+### HTML 中的图像
+
+我们的情书尚未完成，但在继续之前，缺少一件大事：蝙蝠侠标志。你见过是蝙蝠侠的东西但没有蝙蝠侠的标志吗？
+
+并没有。
+
+所以，让我们在情书中添加一个蝙蝠侠标志。
+
+在 HTML 中包含图像就像在一个 Word 文件中包含图像一样。在 MS Word 中，你到 “菜单 -> 插入 -> 图像 -> 然后导航到图像位置为止 -> 选择图像 -> 单击插入”。
+
+在 HTML 中，我们使用 `![]()
` 标签让浏览器知道我们需要加载的图像，而不是单击菜单。我们在 `src` 属性中写入文件的位置和名称。如果图像在项目根目录中，我们可以简单地在 `src` 属性中写入图像文件的名称。
+
+在我们深入编码之前，从[这里][3]下载蝙蝠侠标志。你可能希望裁剪图像中的额外空白区域。复制项目根目录中的图像并将其重命名为 “bat-logo.jpeg”。
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+我们在第 3 行包含了 `![]()
` 标签。这个标签也是一个自闭合的标签，所以我们不需要写 ``。在 `src` 属性中，我们给出了图像文件的名称。这个名称应与图像名称完全相同，包括扩展名（.jpeg）及其大小写。
+
+保存并刷新，查看结果。
+
+
+
+该死的！刚刚发生了什么？
+
+当使用 `![]()
` 标签包含图像时，默认情况下，图像将以其原始分辨率显示。在我们的例子中，图像比 550px 宽得多。让我们使用 `style` 属性定义它的宽度：
+
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+你会注意到，这次我们定义宽度使用了 “%” 而不是 “px”。当我们在 “%” 中定义宽度时，它将占据父元素宽度的百分比。因此，100% 的 550px 将为我们提供 550px。
+
+保存并刷新，查看结果。
+
+
+
+太棒了！这让蝙蝠侠的脸露出了羞涩的微笑 :)。
+
+### HTML 中的粗体和斜体
+
+现在蝙蝠侠想在最后几段中承认他的爱。他有以下文本供你用 HTML 编写：
+
+“I have a confession to make
+
+It feels like my chest _does_ have a heart. You make my heart beat. Your smile brings a smile to my face, your pain brings pain to my heart.
+
+I don’t show my emotions, but I think this man behind the mask is falling for you.”
+
+当阅读到这里时，你会问蝙蝠侠：“等等，这是给谁的？”蝙蝠侠说：
+
+“这是给超人的。”
+
+
+
+你说：哦！我还以为是给神奇女侠的呢。
+
+蝙蝠侠说：不，这是给超人的，请在最后写上 “I love you Superman.”。
+
+好的，我们来写：
+
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+这封信差不多完成了，蝙蝠侠另外想再做两次改变。蝙蝠侠希望在最后段落的第一句中的 “does” 一词是斜体，而 “I love you Superman” 这句话是粗体的。
+
+我们使用 `` 和 `` 以斜体和粗体显示文本。让我们来更新这些更改：
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+
+
+### HTML 中的样式
+
+你可以通过三种方式设置样式或定义 HTML 元素的外观：
+
+* 内联样式：我们使用元素的 `style` 属性来编写样式。这是我们迄今为止使用的，但这不是一个好的实践。
+* 嵌入式样式：我们在由 `` 包裹的 “style” 元素中编写所有样式。
+* 链接样式表：我们在具有 .css 扩展名的单独文件中编写所有元素的样式。此文件称为样式表。
+
+让我们来看看如何定义 `` 的内联样式：
+
+```
+
+```
+
+我们可以在 `` 里面写同样的样式：
+
+```
+div{
+ width:550px;
+}
+```
+
+在嵌入式样式中，我们编写的样式是与元素分开的。所以我们需要一种方法来关联元素及其样式。第一个单词 “div” 就做了这样的活。它让浏览器知道花括号 `{...}` 里面的所有样式都属于 “div” 元素。由于这种语法确定要应用样式的元素，因此它称为一个选择器。
+
+我们编写样式的方式保持不变：属性（`width`）和值（`550px`）用冒号（`:`）分隔，以分号（`;`）结束。
+
+让我们从 `` 和 `![]()
` 元素中删除内联样式，将其写入 `
+```
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+保存并刷新，结果应保持不变。
+
+但是有一个大问题，如果我们的 HTML 文件中有多个 `` 和 `![]()
` 元素该怎么办？这样我们在 `
+```
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+HTML 已经准备好了嵌入式样式。
+
+但是，你可以看到，随着我们包含越来越多的样式，`` 将变得很大。这可能很快会混乱我们的主 HTML 文件。
+
+因此，让我们更进一步，通过将 ``。
+
+我们需要使用 HTML 文件中的 `` 标签来将新创建的 CSS 文件链接到 HTML 文件。以下是我们如何做到这一点：
+
+```
+
+```
+
+我们使用 `` 元素在 HTML 文档中包含外部资源，它主要用于链接样式表。我们使用的三个属性是：
+
+* `rel`：关系。链接文件与文档的关系。具有 .css 扩展名的文件称为样式表，因此我们保留 rel=“stylesheet”。
+* `type`：链接文件的类型；对于一个 CSS 文件来说它是 “text/css”。
+* `href`：超文本参考。链接文件的位置。
+
+link 元素的结尾没有 ``。因此，`` 也是一个自闭合的标签。
+
+```
+
+```
+
+如果只是得到一个女朋友，那么很容易：D
+
+可惜没有那么简单，让我们继续前进。
+
+这是我们 “loveletter.html” 的内容：
+
+```
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+“style.css” 内容：
+
+```
+#letter-container{
+ width:550px;
+}
+#header-bat-logo{
+ width:100%;
+}
+```
+
+保存文件并刷新，浏览器中的输出应保持不变。
+
+### 一些手续
+
+我们的情书已经准备好给蝙蝠侠，但还有一些正式的片段。
+
+与其他任何编程语言一样，HTML 自出生以来（1990 年）经历过许多版本，当前版本是 HTML5。
+
+那么，浏览器如何知道你使用哪个版本的 HTML 来编写页面呢？要告诉浏览器你正在使用 HTML5，你需要在页面顶部包含 ``。对于旧版本的 HTML，这行不同，但你不需要了解它们，因为我们不再使用它们了。
+
+此外，在之前的 HTML 版本中，我们曾经将整个文档封装在 `` 标签内。整个文件分为两个主要部分：头部在 `` 里面，主体在 `` 里面。这在 HTML5 中不是必须的，但由于兼容性原因，我们仍然这样做。让我们用 ``, ``、 `` 和 `` 更新我们的代码：
+
+```
+
+
+
+
+
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+
+
+```
+
+主要内容在 `` 里面，元信息在 `` 里面。所以我们把 `` 保存在 `` 里面并加载 `` 里面的样式表。
+
+保存并刷新，你的 HTML 页面应显示与之前相同的内容。
+
+### HTML 的标题
+
+我发誓，这是最后一次改变。
+
+你可能已经注意到选项卡的标题正在显示 HTML 文件的路径：
+
+
+
+我们可以使用 `` 标签来定义 HTML 文件的标题。标题标签也像链接标签一样在 `<head>` 内部。让我们我们在标题中加上 “Bat Letter”：
+
+```
+<!DOCTYPE html>
+<html>
+<head>
+ <title>Bat Letter
+
+
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+
+
+```
+
+保存并刷新，你将看到在选项卡上显示的是 “Bat Letter” 而不是文件路径。
+
+蝙蝠侠的情书现在已经完成。
+
+恭喜！你用 HTML 制作了蝙蝠侠的情书。
+
+
+
+### 我们学到了什么
+
+我们学习了以下新概念：
+
+ * 一个 HTML 文档的结构
+ * 在 HTML 中如何写元素（``）
+ * 如何使用 style 属性在元素内编写样式（这称为内联样式，尽可能避免这种情况）
+ * 如何在 `` 中编写元素的样式（这称为嵌入式样式）
+ * 在 HTML 中如何使用 `` 在单独的文件中编写样式并链接它（这称为链接样式表）
+ * 什么是标签名称，属性，开始标签和结束标签
+ * 如何使用 id 属性为一个元素赋予 id
+ * CSS 中的标签选择器和 id 选择器
+
+我们学习了以下 HTML 标签：
+
+ * ``：用于段落
+ * `
`：用于换行
+ * `
`、`
`、``、`` 和 `` 标签来添加标题，`` 是最大的标题和最主要的标题，`` 是最小的标题。
+
+
+
+让我们在第二段之前使用 `` 做主标题和一个副标题：
+
+```
+
+ Bat Letter
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+保存，刷新。
+
+
+
+### HTML 中的图像
+
+我们的情书尚未完成，但在继续之前，缺少一件大事：蝙蝠侠标志。你见过是蝙蝠侠的东西但没有蝙蝠侠的标志吗？
+
+并没有。
+
+所以，让我们在情书中添加一个蝙蝠侠标志。
+
+在 HTML 中包含图像就像在一个 Word 文件中包含图像一样。在 MS Word 中，你到 “菜单 -> 插入 -> 图像 -> 然后导航到图像位置为止 -> 选择图像 -> 单击插入”。
+
+在 HTML 中，我们使用 `![]()
` 标签让浏览器知道我们需要加载的图像，而不是单击菜单。我们在 `src` 属性中写入文件的位置和名称。如果图像在项目根目录中，我们可以简单地在 `src` 属性中写入图像文件的名称。
+
+在我们深入编码之前，从[这里][3]下载蝙蝠侠标志。你可能希望裁剪图像中的额外空白区域。复制项目根目录中的图像并将其重命名为 “bat-logo.jpeg”。
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+我们在第 3 行包含了 `![]()
` 标签。这个标签也是一个自闭合的标签，所以我们不需要写 ``。在 `src` 属性中，我们给出了图像文件的名称。这个名称应与图像名称完全相同，包括扩展名（.jpeg）及其大小写。
+
+保存并刷新，查看结果。
+
+
+
+该死的！刚刚发生了什么？
+
+当使用 `![]()
` 标签包含图像时，默认情况下，图像将以其原始分辨率显示。在我们的例子中，图像比 550px 宽得多。让我们使用 `style` 属性定义它的宽度：
+
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+你会注意到，这次我们定义宽度使用了 “%” 而不是 “px”。当我们在 “%” 中定义宽度时，它将占据父元素宽度的百分比。因此，100% 的 550px 将为我们提供 550px。
+
+保存并刷新，查看结果。
+
+
+
+太棒了！这让蝙蝠侠的脸露出了羞涩的微笑 :)。
+
+### HTML 中的粗体和斜体
+
+现在蝙蝠侠想在最后几段中承认他的爱。他有以下文本供你用 HTML 编写：
+
+“I have a confession to make
+
+It feels like my chest _does_ have a heart. You make my heart beat. Your smile brings a smile to my face, your pain brings pain to my heart.
+
+I don’t show my emotions, but I think this man behind the mask is falling for you.”
+
+当阅读到这里时，你会问蝙蝠侠：“等等，这是给谁的？”蝙蝠侠说：
+
+“这是给超人的。”
+
+
+
+你说：哦！我还以为是给神奇女侠的呢。
+
+蝙蝠侠说：不，这是给超人的，请在最后写上 “I love you Superman.”。
+
+好的，我们来写：
+
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+这封信差不多完成了，蝙蝠侠另外想再做两次改变。蝙蝠侠希望在最后段落的第一句中的 “does” 一词是斜体，而 “I love you Superman” 这句话是粗体的。
+
+我们使用 `` 和 `` 以斜体和粗体显示文本。让我们来更新这些更改：
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+
+
+### HTML 中的样式
+
+你可以通过三种方式设置样式或定义 HTML 元素的外观：
+
+* 内联样式：我们使用元素的 `style` 属性来编写样式。这是我们迄今为止使用的，但这不是一个好的实践。
+* 嵌入式样式：我们在由 `` 包裹的 “style” 元素中编写所有样式。
+* 链接样式表：我们在具有 .css 扩展名的单独文件中编写所有元素的样式。此文件称为样式表。
+
+让我们来看看如何定义 `` 的内联样式：
+
+```
+
+```
+
+我们可以在 `` 里面写同样的样式：
+
+```
+div{
+ width:550px;
+}
+```
+
+在嵌入式样式中，我们编写的样式是与元素分开的。所以我们需要一种方法来关联元素及其样式。第一个单词 “div” 就做了这样的活。它让浏览器知道花括号 `{...}` 里面的所有样式都属于 “div” 元素。由于这种语法确定要应用样式的元素，因此它称为一个选择器。
+
+我们编写样式的方式保持不变：属性（`width`）和值（`550px`）用冒号（`:`）分隔，以分号（`;`）结束。
+
+让我们从 `` 和 `![]()
` 元素中删除内联样式，将其写入 `
+```
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+保存并刷新，结果应保持不变。
+
+但是有一个大问题，如果我们的 HTML 文件中有多个 `` 和 `![]()
` 元素该怎么办？这样我们在 `
+```
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+HTML 已经准备好了嵌入式样式。
+
+但是，你可以看到，随着我们包含越来越多的样式，`` 将变得很大。这可能很快会混乱我们的主 HTML 文件。
+
+因此，让我们更进一步，通过将 ``。
+
+我们需要使用 HTML 文件中的 `` 标签来将新创建的 CSS 文件链接到 HTML 文件。以下是我们如何做到这一点：
+
+```
+
+```
+
+我们使用 `` 元素在 HTML 文档中包含外部资源，它主要用于链接样式表。我们使用的三个属性是：
+
+* `rel`：关系。链接文件与文档的关系。具有 .css 扩展名的文件称为样式表，因此我们保留 rel=“stylesheet”。
+* `type`：链接文件的类型；对于一个 CSS 文件来说它是 “text/css”。
+* `href`：超文本参考。链接文件的位置。
+
+link 元素的结尾没有 ``。因此，`` 也是一个自闭合的标签。
+
+```
+
+```
+
+如果只是得到一个女朋友，那么很容易：D
+
+可惜没有那么简单，让我们继续前进。
+
+这是我们 “loveletter.html” 的内容：
+
+```
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+“style.css” 内容：
+
+```
+#letter-container{
+ width:550px;
+}
+#header-bat-logo{
+ width:100%;
+}
+```
+
+保存文件并刷新，浏览器中的输出应保持不变。
+
+### 一些手续
+
+我们的情书已经准备好给蝙蝠侠，但还有一些正式的片段。
+
+与其他任何编程语言一样，HTML 自出生以来（1990 年）经历过许多版本，当前版本是 HTML5。
+
+那么，浏览器如何知道你使用哪个版本的 HTML 来编写页面呢？要告诉浏览器你正在使用 HTML5，你需要在页面顶部包含 ``。对于旧版本的 HTML，这行不同，但你不需要了解它们，因为我们不再使用它们了。
+
+此外，在之前的 HTML 版本中，我们曾经将整个文档封装在 `` 标签内。整个文件分为两个主要部分：头部在 `` 里面，主体在 `` 里面。这在 HTML5 中不是必须的，但由于兼容性原因，我们仍然这样做。让我们用 ``, ``、 `` 和 `` 更新我们的代码：
+
+```
+
+
+
+
+
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+
+
+```
+
+主要内容在 `` 里面，元信息在 `` 里面。所以我们把 `` 保存在 `` 里面并加载 `` 里面的样式表。
+
+保存并刷新，你的 HTML 页面应显示与之前相同的内容。
+
+### HTML 的标题
+
+我发誓，这是最后一次改变。
+
+你可能已经注意到选项卡的标题正在显示 HTML 文件的路径：
+
+
+
+我们可以使用 `` 标签来定义 HTML 文件的标题。标题标签也像链接标签一样在 `<head>` 内部。让我们我们在标题中加上 “Bat Letter”：
+
+```
+<!DOCTYPE html>
+<html>
+<head>
+ <title>Bat Letter
+
+
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+
+
+```
+
+保存并刷新，你将看到在选项卡上显示的是 “Bat Letter” 而不是文件路径。
+
+蝙蝠侠的情书现在已经完成。
+
+恭喜！你用 HTML 制作了蝙蝠侠的情书。
+
+
+
+### 我们学到了什么
+
+我们学习了以下新概念：
+
+ * 一个 HTML 文档的结构
+ * 在 HTML 中如何写元素（``）
+ * 如何使用 style 属性在元素内编写样式（这称为内联样式，尽可能避免这种情况）
+ * 如何在 `` 中编写元素的样式（这称为嵌入式样式）
+ * 在 HTML 中如何使用 `` 在单独的文件中编写样式并链接它（这称为链接样式表）
+ * 什么是标签名称，属性，开始标签和结束标签
+ * 如何使用 id 属性为一个元素赋予 id
+ * CSS 中的标签选择器和 id 选择器
+
+我们学习了以下 HTML 标签：
+
+ * ``：用于段落
+ * `
`：用于换行
+ * `
`、`
` 和 `` 标签来添加标题，`` 是最大的标题和最主要的标题，`` 是最小的标题。
+
+
+
+让我们在第二段之前使用 `` 做主标题和一个副标题：
+
+```
+
+ Bat Letter
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+保存，刷新。
+
+
+
+### HTML 中的图像
+
+我们的情书尚未完成，但在继续之前，缺少一件大事：蝙蝠侠标志。你见过是蝙蝠侠的东西但没有蝙蝠侠的标志吗？
+
+并没有。
+
+所以，让我们在情书中添加一个蝙蝠侠标志。
+
+在 HTML 中包含图像就像在一个 Word 文件中包含图像一样。在 MS Word 中，你到 “菜单 -> 插入 -> 图像 -> 然后导航到图像位置为止 -> 选择图像 -> 单击插入”。
+
+在 HTML 中，我们使用 `![]()
` 标签让浏览器知道我们需要加载的图像，而不是单击菜单。我们在 `src` 属性中写入文件的位置和名称。如果图像在项目根目录中，我们可以简单地在 `src` 属性中写入图像文件的名称。
+
+在我们深入编码之前，从[这里][3]下载蝙蝠侠标志。你可能希望裁剪图像中的额外空白区域。复制项目根目录中的图像并将其重命名为 “bat-logo.jpeg”。
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+我们在第 3 行包含了 `![]()
` 标签。这个标签也是一个自闭合的标签，所以我们不需要写 ``。在 `src` 属性中，我们给出了图像文件的名称。这个名称应与图像名称完全相同，包括扩展名（.jpeg）及其大小写。
+
+保存并刷新，查看结果。
+
+
+
+该死的！刚刚发生了什么？
+
+当使用 `![]()
` 标签包含图像时，默认情况下，图像将以其原始分辨率显示。在我们的例子中，图像比 550px 宽得多。让我们使用 `style` 属性定义它的宽度：
+
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+你会注意到，这次我们定义宽度使用了 “%” 而不是 “px”。当我们在 “%” 中定义宽度时，它将占据父元素宽度的百分比。因此，100% 的 550px 将为我们提供 550px。
+
+保存并刷新，查看结果。
+
+
+
+太棒了！这让蝙蝠侠的脸露出了羞涩的微笑 :)。
+
+### HTML 中的粗体和斜体
+
+现在蝙蝠侠想在最后几段中承认他的爱。他有以下文本供你用 HTML 编写：
+
+“I have a confession to make
+
+It feels like my chest _does_ have a heart. You make my heart beat. Your smile brings a smile to my face, your pain brings pain to my heart.
+
+I don’t show my emotions, but I think this man behind the mask is falling for you.”
+
+当阅读到这里时，你会问蝙蝠侠：“等等，这是给谁的？”蝙蝠侠说：
+
+“这是给超人的。”
+
+
+
+你说：哦！我还以为是给神奇女侠的呢。
+
+蝙蝠侠说：不，这是给超人的，请在最后写上 “I love you Superman.”。
+
+好的，我们来写：
+
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+这封信差不多完成了，蝙蝠侠另外想再做两次改变。蝙蝠侠希望在最后段落的第一句中的 “does” 一词是斜体，而 “I love you Superman” 这句话是粗体的。
+
+我们使用 `` 和 `` 以斜体和粗体显示文本。让我们来更新这些更改：
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+
+
+### HTML 中的样式
+
+你可以通过三种方式设置样式或定义 HTML 元素的外观：
+
+* 内联样式：我们使用元素的 `style` 属性来编写样式。这是我们迄今为止使用的，但这不是一个好的实践。
+* 嵌入式样式：我们在由 `` 包裹的 “style” 元素中编写所有样式。
+* 链接样式表：我们在具有 .css 扩展名的单独文件中编写所有元素的样式。此文件称为样式表。
+
+让我们来看看如何定义 `` 的内联样式：
+
+```
+
+```
+
+我们可以在 `` 里面写同样的样式：
+
+```
+div{
+ width:550px;
+}
+```
+
+在嵌入式样式中，我们编写的样式是与元素分开的。所以我们需要一种方法来关联元素及其样式。第一个单词 “div” 就做了这样的活。它让浏览器知道花括号 `{...}` 里面的所有样式都属于 “div” 元素。由于这种语法确定要应用样式的元素，因此它称为一个选择器。
+
+我们编写样式的方式保持不变：属性（`width`）和值（`550px`）用冒号（`:`）分隔，以分号（`;`）结束。
+
+让我们从 `` 和 `![]()
` 元素中删除内联样式，将其写入 `
+```
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+保存并刷新，结果应保持不变。
+
+但是有一个大问题，如果我们的 HTML 文件中有多个 `` 和 `![]()
` 元素该怎么办？这样我们在 `
+```
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+HTML 已经准备好了嵌入式样式。
+
+但是，你可以看到，随着我们包含越来越多的样式，`` 将变得很大。这可能很快会混乱我们的主 HTML 文件。
+
+因此，让我们更进一步，通过将 ``。
+
+我们需要使用 HTML 文件中的 `` 标签来将新创建的 CSS 文件链接到 HTML 文件。以下是我们如何做到这一点：
+
+```
+
+```
+
+我们使用 `` 元素在 HTML 文档中包含外部资源，它主要用于链接样式表。我们使用的三个属性是：
+
+* `rel`：关系。链接文件与文档的关系。具有 .css 扩展名的文件称为样式表，因此我们保留 rel=“stylesheet”。
+* `type`：链接文件的类型；对于一个 CSS 文件来说它是 “text/css”。
+* `href`：超文本参考。链接文件的位置。
+
+link 元素的结尾没有 ``。因此，`` 也是一个自闭合的标签。
+
+```
+
+```
+
+如果只是得到一个女朋友，那么很容易：D
+
+可惜没有那么简单，让我们继续前进。
+
+这是我们 “loveletter.html” 的内容：
+
+```
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+“style.css” 内容：
+
+```
+#letter-container{
+ width:550px;
+}
+#header-bat-logo{
+ width:100%;
+}
+```
+
+保存文件并刷新，浏览器中的输出应保持不变。
+
+### 一些手续
+
+我们的情书已经准备好给蝙蝠侠，但还有一些正式的片段。
+
+与其他任何编程语言一样，HTML 自出生以来（1990 年）经历过许多版本，当前版本是 HTML5。
+
+那么，浏览器如何知道你使用哪个版本的 HTML 来编写页面呢？要告诉浏览器你正在使用 HTML5，你需要在页面顶部包含 ``。对于旧版本的 HTML，这行不同，但你不需要了解它们，因为我们不再使用它们了。
+
+此外，在之前的 HTML 版本中，我们曾经将整个文档封装在 `` 标签内。整个文件分为两个主要部分：头部在 `` 里面，主体在 `` 里面。这在 HTML5 中不是必须的，但由于兼容性原因，我们仍然这样做。让我们用 ``, ``、 `` 和 `` 更新我们的代码：
+
+```
+
+
+
+
+
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+
+
+```
+
+主要内容在 `` 里面，元信息在 `` 里面。所以我们把 `` 保存在 `` 里面并加载 `` 里面的样式表。
+
+保存并刷新，你的 HTML 页面应显示与之前相同的内容。
+
+### HTML 的标题
+
+我发誓，这是最后一次改变。
+
+你可能已经注意到选项卡的标题正在显示 HTML 文件的路径：
+
+
+
+我们可以使用 `` 标签来定义 HTML 文件的标题。标题标签也像链接标签一样在 `<head>` 内部。让我们我们在标题中加上 “Bat Letter”：
+
+```
+<!DOCTYPE html>
+<html>
+<head>
+ <title>Bat Letter
+
+
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+
+
+```
+
+保存并刷新，你将看到在选项卡上显示的是 “Bat Letter” 而不是文件路径。
+
+蝙蝠侠的情书现在已经完成。
+
+恭喜！你用 HTML 制作了蝙蝠侠的情书。
+
+
+
+### 我们学到了什么
+
+我们学习了以下新概念：
+
+ * 一个 HTML 文档的结构
+ * 在 HTML 中如何写元素（``）
+ * 如何使用 style 属性在元素内编写样式（这称为内联样式，尽可能避免这种情况）
+ * 如何在 `` 中编写元素的样式（这称为嵌入式样式）
+ * 在 HTML 中如何使用 `` 在单独的文件中编写样式并链接它（这称为链接样式表）
+ * 什么是标签名称，属性，开始标签和结束标签
+ * 如何使用 id 属性为一个元素赋予 id
+ * CSS 中的标签选择器和 id 选择器
+
+我们学习了以下 HTML 标签：
+
+ * ``：用于段落
+ * `
`：用于换行
+ * `
`、`
` 是最大的标题和最主要的标题，`` 是最小的标题。
+
+
+
+让我们在第二段之前使用 `` 做主标题和一个副标题：
+
+```
+
+ Bat Letter
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+保存，刷新。
+
+
+
+### HTML 中的图像
+
+我们的情书尚未完成，但在继续之前，缺少一件大事：蝙蝠侠标志。你见过是蝙蝠侠的东西但没有蝙蝠侠的标志吗？
+
+并没有。
+
+所以，让我们在情书中添加一个蝙蝠侠标志。
+
+在 HTML 中包含图像就像在一个 Word 文件中包含图像一样。在 MS Word 中，你到 “菜单 -> 插入 -> 图像 -> 然后导航到图像位置为止 -> 选择图像 -> 单击插入”。
+
+在 HTML 中，我们使用 `![]()
` 标签让浏览器知道我们需要加载的图像，而不是单击菜单。我们在 `src` 属性中写入文件的位置和名称。如果图像在项目根目录中，我们可以简单地在 `src` 属性中写入图像文件的名称。
+
+在我们深入编码之前，从[这里][3]下载蝙蝠侠标志。你可能希望裁剪图像中的额外空白区域。复制项目根目录中的图像并将其重命名为 “bat-logo.jpeg”。
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+我们在第 3 行包含了 `![]()
` 标签。这个标签也是一个自闭合的标签，所以我们不需要写 ``。在 `src` 属性中，我们给出了图像文件的名称。这个名称应与图像名称完全相同，包括扩展名（.jpeg）及其大小写。
+
+保存并刷新，查看结果。
+
+
+
+该死的！刚刚发生了什么？
+
+当使用 `![]()
` 标签包含图像时，默认情况下，图像将以其原始分辨率显示。在我们的例子中，图像比 550px 宽得多。让我们使用 `style` 属性定义它的宽度：
+
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+你会注意到，这次我们定义宽度使用了 “%” 而不是 “px”。当我们在 “%” 中定义宽度时，它将占据父元素宽度的百分比。因此，100% 的 550px 将为我们提供 550px。
+
+保存并刷新，查看结果。
+
+
+
+太棒了！这让蝙蝠侠的脸露出了羞涩的微笑 :)。
+
+### HTML 中的粗体和斜体
+
+现在蝙蝠侠想在最后几段中承认他的爱。他有以下文本供你用 HTML 编写：
+
+“I have a confession to make
+
+It feels like my chest _does_ have a heart. You make my heart beat. Your smile brings a smile to my face, your pain brings pain to my heart.
+
+I don’t show my emotions, but I think this man behind the mask is falling for you.”
+
+当阅读到这里时，你会问蝙蝠侠：“等等，这是给谁的？”蝙蝠侠说：
+
+“这是给超人的。”
+
+
+
+你说：哦！我还以为是给神奇女侠的呢。
+
+蝙蝠侠说：不，这是给超人的，请在最后写上 “I love you Superman.”。
+
+好的，我们来写：
+
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+这封信差不多完成了，蝙蝠侠另外想再做两次改变。蝙蝠侠希望在最后段落的第一句中的 “does” 一词是斜体，而 “I love you Superman” 这句话是粗体的。
+
+我们使用 `` 和 `` 以斜体和粗体显示文本。让我们来更新这些更改：
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+
+
+### HTML 中的样式
+
+你可以通过三种方式设置样式或定义 HTML 元素的外观：
+
+* 内联样式：我们使用元素的 `style` 属性来编写样式。这是我们迄今为止使用的，但这不是一个好的实践。
+* 嵌入式样式：我们在由 `` 包裹的 “style” 元素中编写所有样式。
+* 链接样式表：我们在具有 .css 扩展名的单独文件中编写所有元素的样式。此文件称为样式表。
+
+让我们来看看如何定义 `` 的内联样式：
+
+```
+
+```
+
+我们可以在 `` 里面写同样的样式：
+
+```
+div{
+ width:550px;
+}
+```
+
+在嵌入式样式中，我们编写的样式是与元素分开的。所以我们需要一种方法来关联元素及其样式。第一个单词 “div” 就做了这样的活。它让浏览器知道花括号 `{...}` 里面的所有样式都属于 “div” 元素。由于这种语法确定要应用样式的元素，因此它称为一个选择器。
+
+我们编写样式的方式保持不变：属性（`width`）和值（`550px`）用冒号（`:`）分隔，以分号（`;`）结束。
+
+让我们从 `` 和 `![]()
` 元素中删除内联样式，将其写入 `
+```
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+保存并刷新，结果应保持不变。
+
+但是有一个大问题，如果我们的 HTML 文件中有多个 `` 和 `![]()
` 元素该怎么办？这样我们在 `
+```
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+HTML 已经准备好了嵌入式样式。
+
+但是，你可以看到，随着我们包含越来越多的样式，`` 将变得很大。这可能很快会混乱我们的主 HTML 文件。
+
+因此，让我们更进一步，通过将 ``。
+
+我们需要使用 HTML 文件中的 `` 标签来将新创建的 CSS 文件链接到 HTML 文件。以下是我们如何做到这一点：
+
+```
+
+```
+
+我们使用 `` 元素在 HTML 文档中包含外部资源，它主要用于链接样式表。我们使用的三个属性是：
+
+* `rel`：关系。链接文件与文档的关系。具有 .css 扩展名的文件称为样式表，因此我们保留 rel=“stylesheet”。
+* `type`：链接文件的类型；对于一个 CSS 文件来说它是 “text/css”。
+* `href`：超文本参考。链接文件的位置。
+
+link 元素的结尾没有 ``。因此，`` 也是一个自闭合的标签。
+
+```
+
+```
+
+如果只是得到一个女朋友，那么很容易：D
+
+可惜没有那么简单，让我们继续前进。
+
+这是我们 “loveletter.html” 的内容：
+
+```
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+“style.css” 内容：
+
+```
+#letter-container{
+ width:550px;
+}
+#header-bat-logo{
+ width:100%;
+}
+```
+
+保存文件并刷新，浏览器中的输出应保持不变。
+
+### 一些手续
+
+我们的情书已经准备好给蝙蝠侠，但还有一些正式的片段。
+
+与其他任何编程语言一样，HTML 自出生以来（1990 年）经历过许多版本，当前版本是 HTML5。
+
+那么，浏览器如何知道你使用哪个版本的 HTML 来编写页面呢？要告诉浏览器你正在使用 HTML5，你需要在页面顶部包含 ``。对于旧版本的 HTML，这行不同，但你不需要了解它们，因为我们不再使用它们了。
+
+此外，在之前的 HTML 版本中，我们曾经将整个文档封装在 `` 标签内。整个文件分为两个主要部分：头部在 `` 里面，主体在 `` 里面。这在 HTML5 中不是必须的，但由于兼容性原因，我们仍然这样做。让我们用 ``, ``、 `` 和 `` 更新我们的代码：
+
+```
+
+
+
+
+
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+
+
+```
+
+主要内容在 `` 里面，元信息在 `` 里面。所以我们把 `` 保存在 `` 里面并加载 `` 里面的样式表。
+
+保存并刷新，你的 HTML 页面应显示与之前相同的内容。
+
+### HTML 的标题
+
+我发誓，这是最后一次改变。
+
+你可能已经注意到选项卡的标题正在显示 HTML 文件的路径：
+
+
+
+我们可以使用 `` 标签来定义 HTML 文件的标题。标题标签也像链接标签一样在 `<head>` 内部。让我们我们在标题中加上 “Bat Letter”：
+
+```
+<!DOCTYPE html>
+<html>
+<head>
+ <title>Bat Letter
+
+
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+
+
+```
+
+保存并刷新，你将看到在选项卡上显示的是 “Bat Letter” 而不是文件路径。
+
+蝙蝠侠的情书现在已经完成。
+
+恭喜！你用 HTML 制作了蝙蝠侠的情书。
+
+
+
+### 我们学到了什么
+
+我们学习了以下新概念：
+
+ * 一个 HTML 文档的结构
+ * 在 HTML 中如何写元素（``）
+ * 如何使用 style 属性在元素内编写样式（这称为内联样式，尽可能避免这种情况）
+ * 如何在 `` 中编写元素的样式（这称为嵌入式样式）
+ * 在 HTML 中如何使用 `` 在单独的文件中编写样式并链接它（这称为链接样式表）
+ * 什么是标签名称，属性，开始标签和结束标签
+ * 如何使用 id 属性为一个元素赋予 id
+ * CSS 中的标签选择器和 id 选择器
+
+我们学习了以下 HTML 标签：
+
+ * ``：用于段落
+ * `
`：用于换行
+ * `
`、`
` 做主标题和一个副标题：
+
+```
+
+ Bat Letter
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+保存，刷新。
+
+
+
+### HTML 中的图像
+
+我们的情书尚未完成，但在继续之前，缺少一件大事：蝙蝠侠标志。你见过是蝙蝠侠的东西但没有蝙蝠侠的标志吗？
+
+并没有。
+
+所以，让我们在情书中添加一个蝙蝠侠标志。
+
+在 HTML 中包含图像就像在一个 Word 文件中包含图像一样。在 MS Word 中，你到 “菜单 -> 插入 -> 图像 -> 然后导航到图像位置为止 -> 选择图像 -> 单击插入”。
+
+在 HTML 中，我们使用 `![]()
` 标签让浏览器知道我们需要加载的图像，而不是单击菜单。我们在 `src` 属性中写入文件的位置和名称。如果图像在项目根目录中，我们可以简单地在 `src` 属性中写入图像文件的名称。
+
+在我们深入编码之前，从[这里][3]下载蝙蝠侠标志。你可能希望裁剪图像中的额外空白区域。复制项目根目录中的图像并将其重命名为 “bat-logo.jpeg”。
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+我们在第 3 行包含了 `![]()
` 标签。这个标签也是一个自闭合的标签，所以我们不需要写 ``。在 `src` 属性中，我们给出了图像文件的名称。这个名称应与图像名称完全相同，包括扩展名（.jpeg）及其大小写。
+
+保存并刷新，查看结果。
+
+
+
+该死的！刚刚发生了什么？
+
+当使用 `![]()
` 标签包含图像时，默认情况下，图像将以其原始分辨率显示。在我们的例子中，图像比 550px 宽得多。让我们使用 `style` 属性定义它的宽度：
+
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+
+```
+
+你会注意到，这次我们定义宽度使用了 “%” 而不是 “px”。当我们在 “%” 中定义宽度时，它将占据父元素宽度的百分比。因此，100% 的 550px 将为我们提供 550px。
+
+保存并刷新，查看结果。
+
+
+
+太棒了！这让蝙蝠侠的脸露出了羞涩的微笑 :)。
+
+### HTML 中的粗体和斜体
+
+现在蝙蝠侠想在最后几段中承认他的爱。他有以下文本供你用 HTML 编写：
+
+“I have a confession to make
+
+It feels like my chest _does_ have a heart. You make my heart beat. Your smile brings a smile to my face, your pain brings pain to my heart.
+
+I don’t show my emotions, but I think this man behind the mask is falling for you.”
+
+当阅读到这里时，你会问蝙蝠侠：“等等，这是给谁的？”蝙蝠侠说：
+
+“这是给超人的。”
+
+
+
+你说：哦！我还以为是给神奇女侠的呢。
+
+蝙蝠侠说：不，这是给超人的，请在最后写上 “I love you Superman.”。
+
+好的，我们来写：
+
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+这封信差不多完成了，蝙蝠侠另外想再做两次改变。蝙蝠侠希望在最后段落的第一句中的 “does” 一词是斜体，而 “I love you Superman” 这句话是粗体的。
+
+我们使用 `` 和 `` 以斜体和粗体显示文本。让我们来更新这些更改：
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+
+
+### HTML 中的样式
+
+你可以通过三种方式设置样式或定义 HTML 元素的外观：
+
+* 内联样式：我们使用元素的 `style` 属性来编写样式。这是我们迄今为止使用的，但这不是一个好的实践。
+* 嵌入式样式：我们在由 `` 包裹的 “style” 元素中编写所有样式。
+* 链接样式表：我们在具有 .css 扩展名的单独文件中编写所有元素的样式。此文件称为样式表。
+
+让我们来看看如何定义 `` 的内联样式：
+
+```
+
+```
+
+我们可以在 `` 里面写同样的样式：
+
+```
+div{
+ width:550px;
+}
+```
+
+在嵌入式样式中，我们编写的样式是与元素分开的。所以我们需要一种方法来关联元素及其样式。第一个单词 “div” 就做了这样的活。它让浏览器知道花括号 `{...}` 里面的所有样式都属于 “div” 元素。由于这种语法确定要应用样式的元素，因此它称为一个选择器。
+
+我们编写样式的方式保持不变：属性（`width`）和值（`550px`）用冒号（`:`）分隔，以分号（`;`）结束。
+
+让我们从 `` 和 `![]()
` 元素中删除内联样式，将其写入 `
+```
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+保存并刷新，结果应保持不变。
+
+但是有一个大问题，如果我们的 HTML 文件中有多个 `` 和 `![]()
` 元素该怎么办？这样我们在 `
+```
+
+```
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+```
+
+```
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+HTML 已经准备好了嵌入式样式。
+
+但是，你可以看到，随着我们包含越来越多的样式，`` 将变得很大。这可能很快会混乱我们的主 HTML 文件。
+
+因此，让我们更进一步，通过将 ``。
+
+我们需要使用 HTML 文件中的 `` 标签来将新创建的 CSS 文件链接到 HTML 文件。以下是我们如何做到这一点：
+
+```
+
+```
+
+我们使用 `` 元素在 HTML 文档中包含外部资源，它主要用于链接样式表。我们使用的三个属性是：
+
+* `rel`：关系。链接文件与文档的关系。具有 .css 扩展名的文件称为样式表，因此我们保留 rel=“stylesheet”。
+* `type`：链接文件的类型；对于一个 CSS 文件来说它是 “text/css”。
+* `href`：超文本参考。链接文件的位置。
+
+link 元素的结尾没有 ``。因此，`` 也是一个自闭合的标签。
+
+```
+
+```
+
+如果只是得到一个女朋友，那么很容易：D
+
+可惜没有那么简单，让我们继续前进。
+
+这是我们 “loveletter.html” 的内容：
+
+```
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+```
+
+“style.css” 内容：
+
+```
+#letter-container{
+ width:550px;
+}
+#header-bat-logo{
+ width:100%;
+}
+```
+
+保存文件并刷新，浏览器中的输出应保持不变。
+
+### 一些手续
+
+我们的情书已经准备好给蝙蝠侠，但还有一些正式的片段。
+
+与其他任何编程语言一样，HTML 自出生以来（1990 年）经历过许多版本，当前版本是 HTML5。
+
+那么，浏览器如何知道你使用哪个版本的 HTML 来编写页面呢？要告诉浏览器你正在使用 HTML5，你需要在页面顶部包含 ``。对于旧版本的 HTML，这行不同，但你不需要了解它们，因为我们不再使用它们了。
+
+此外，在之前的 HTML 版本中，我们曾经将整个文档封装在 `` 标签内。整个文件分为两个主要部分：头部在 `` 里面，主体在 `` 里面。这在 HTML5 中不是必须的，但由于兼容性原因，我们仍然这样做。让我们用 ``, ``、 `` 和 `` 更新我们的代码：
+
+```
+
+
+
+
+
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+
+
+```
+
+主要内容在 `` 里面，元信息在 `` 里面。所以我们把 `` 保存在 `` 里面并加载 `` 里面的样式表。
+
+保存并刷新，你的 HTML 页面应显示与之前相同的内容。
+
+### HTML 的标题
+
+我发誓，这是最后一次改变。
+
+你可能已经注意到选项卡的标题正在显示 HTML 文件的路径：
+
+
+
+我们可以使用 `` 标签来定义 HTML 文件的标题。标题标签也像链接标签一样在 `<head>` 内部。让我们我们在标题中加上 “Bat Letter”：
+
+```
+<!DOCTYPE html>
+<html>
+<head>
+ <title>Bat Letter
+
+
+
+
+ Bat Letter
+
+
+ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you.
+
+ You are the light of my life
+
+ You complete my darkness with your light. I love:
+
+
+
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time.
+
+ I have a confession to make
+
+ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart.
+
+
+ I don't show my emotions, but I think this man behind the mask is falling for you.
+
+ I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+
+
+```
+
+保存并刷新，你将看到在选项卡上显示的是 “Bat Letter” 而不是文件路径。
+
+蝙蝠侠的情书现在已经完成。
+
+恭喜！你用 HTML 制作了蝙蝠侠的情书。
+
+
+
+### 我们学到了什么
+
+我们学习了以下新概念：
+
+ * 一个 HTML 文档的结构
+ * 在 HTML 中如何写元素（``）
+ * 如何使用 style 属性在元素内编写样式（这称为内联样式，尽可能避免这种情况）
+ * 如何在 `` 中编写元素的样式（这称为嵌入式样式）
+ * 在 HTML 中如何使用 `` 在单独的文件中编写样式并链接它（这称为链接样式表）
+ * 什么是标签名称，属性，开始标签和结束标签
+ * 如何使用 id 属性为一个元素赋予 id
+ * CSS 中的标签选择器和 id 选择器
+
+我们学习了以下 HTML 标签：
+
+ * ``：用于段落
+ * `
`：用于换行
+ * `
`、`
Bat Letter
++ After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+``` + +``` +You are the light of my life
++ You complete my darkness with your light. I love: +
+-
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time. +
+Bat Letter
+
+ + After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+``` + +``` +You are the light of my life
++ You complete my darkness with your light. I love: +
+-
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time. +
+Bat Letter
+
+ + After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+``` + +``` +You are the light of my life
++ You complete my darkness with your light. I love: +
+-
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time. +
+Bat Letter
+
+ + After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+``` + +``` +You are the light of my life
++ You complete my darkness with your light. I love: +
+-
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time. +
+I have a confession to make
++ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart. +
++ I don't show my emotions, but I think this man behind the mask is falling for you. +
+I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
Bat Letter
+
+ + After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+``` + +``` +You are the light of my life
++ You complete my darkness with your light. I love: +
+-
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time. +
+I have a confession to make
++ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart. +
++ I don't show my emotions, but I think this man behind the mask is falling for you. +
+I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+```
+
+我们可以在 `` 里面写同样的样式：
+
+```
+div{
+ width:550px;
+}
+```
+
+在嵌入式样式中，我们编写的样式是与元素分开的。所以我们需要一种方法来关联元素及其样式。第一个单词 “div” 就做了这样的活。它让浏览器知道花括号 `{...}` 里面的所有样式都属于 “div” 元素。由于这种语法确定要应用样式的元素，因此它称为一个选择器。
+
+我们编写样式的方式保持不变：属性（`width`）和值（`550px`）用冒号（`:`）分隔，以分号（`;`）结束。
+
+让我们从 `
` 和 `![]()
` 元素中删除内联样式，将其写入 `
+```
+
+```
+
+
+
+```
+
+保存并刷新，结果应保持不变。
+
+但是有一个大问题，如果我们的 HTML 文件中有多个 `Bat Letter
+
+ + After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+``` + +``` +You are the light of my life
++ You complete my darkness with your light. I love: +
+-
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time. +
+I have a confession to make
++ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart. +
++ I don't show my emotions, but I think this man behind the mask is falling for you. +
+I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
` 和 `![]()
` 元素该怎么办？这样我们在 `
+```
+
+```
+`, ``、 `` 和 `` 更新我们的代码：
+
+```
+
+
+
+
+
+
+
+
+
+```
+
+HTML 已经准备好了嵌入式样式。
+
+但是，你可以看到，随着我们包含越来越多的样式，`` 将变得很大。这可能很快会混乱我们的主 HTML 文件。
+
+因此，让我们更进一步，通过将 ``。
+
+我们需要使用 HTML 文件中的 `` 标签来将新创建的 CSS 文件链接到 HTML 文件。以下是我们如何做到这一点：
+
+```
+
+```
+
+我们使用 `` 元素在 HTML 文档中包含外部资源，它主要用于链接样式表。我们使用的三个属性是：
+
+* `rel`：关系。链接文件与文档的关系。具有 .css 扩展名的文件称为样式表，因此我们保留 rel=“stylesheet”。
+* `type`：链接文件的类型；对于一个 CSS 文件来说它是 “text/css”。
+* `href`：超文本参考。链接文件的位置。
+
+link 元素的结尾没有 ``。因此，`` 也是一个自闭合的标签。
+
+```
+
+```
+
+如果只是得到一个女朋友，那么很容易：D
+
+可惜没有那么简单，让我们继续前进。
+
+这是我们 “loveletter.html” 的内容：
+
+```
+
+Bat Letter
+
+ + After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+``` + +``` +You are the light of my life
++ You complete my darkness with your light. I love: +
+-
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time. +
+I have a confession to make
++ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart. +
++ I don't show my emotions, but I think this man behind the mask is falling for you. +
+I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+
+```
+
+“style.css” 内容：
+
+```
+#letter-container{
+ width:550px;
+}
+#header-bat-logo{
+ width:100%;
+}
+```
+
+保存文件并刷新，浏览器中的输出应保持不变。
+
+### 一些手续
+
+我们的情书已经准备好给蝙蝠侠，但还有一些正式的片段。
+
+与其他任何编程语言一样，HTML 自出生以来（1990 年）经历过许多版本，当前版本是 HTML5。
+
+那么，浏览器如何知道你使用哪个版本的 HTML 来编写页面呢？要告诉浏览器你正在使用 HTML5，你需要在页面顶部包含 ``。对于旧版本的 HTML，这行不同，但你不需要了解它们，因为我们不再使用它们了。
+
+此外，在之前的 HTML 版本中，我们曾经将整个文档封装在 `` 标签内。整个文件分为两个主要部分：头部在 `` 里面，主体在 `` 里面。这在 HTML5 中不是必须的，但由于兼容性原因，我们仍然这样做。让我们用 `Bat Letter
+
+ + After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+You are the light of my life
++ You complete my darkness with your light. I love: +
+-
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time. +
+I have a confession to make
++ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart. +
++ I don't show my emotions, but I think this man behind the mask is falling for you. +
+I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
+
+
+
+
+```
+
+主要内容在 `` 里面，元信息在 `` 里面。所以我们把 `Bat Letter
+
+ + After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+You are the light of my life
++ You complete my darkness with your light. I love: +
+-
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time. +
+I have a confession to make
++ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart. +
++ I don't show my emotions, but I think this man behind the mask is falling for you. +
+I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
` 保存在 `` 里面并加载 `` 里面的样式表。
+
+保存并刷新，你的 HTML 页面应显示与之前相同的内容。
+
+### HTML 的标题
+
+我发誓，这是最后一次改变。
+
+你可能已经注意到选项卡的标题正在显示 HTML 文件的路径：
+
+
+
+我们可以使用 `` 标签来定义 HTML 文件的标题。标题标签也像链接标签一样在 `<head>` 内部。让我们我们在标题中加上 “Bat Letter”：
+
+```
+<!DOCTYPE html>
+<html>
+<head>
+ <title>Bat Letter
+
+
+
+
+
+
+
+
+```
+
+保存并刷新，你将看到在选项卡上显示的是 “Bat Letter” 而不是文件路径。
+
+蝙蝠侠的情书现在已经完成。
+
+恭喜！你用 HTML 制作了蝙蝠侠的情书。
+
+
+
+### 我们学到了什么
+
+我们学习了以下新概念：
+
+ * 一个 HTML 文档的结构
+ * 在 HTML 中如何写元素（``）
+ * 如何使用 style 属性在元素内编写样式（这称为内联样式，尽可能避免这种情况）
+ * 如何在 `` 中编写元素的样式（这称为嵌入式样式）
+ * 在 HTML 中如何使用 `` 在单独的文件中编写样式并链接它（这称为链接样式表）
+ * 什么是标签名称，属性，开始标签和结束标签
+ * 如何使用 id 属性为一个元素赋予 id
+ * CSS 中的标签选择器和 id 选择器
+
+我们学习了以下 HTML 标签：
+
+ * `Bat Letter
+
+ + After all the battles we faught together, after all the difficult times we saw together, after all the good and bad moments we've been through, I think it's time I let you know how I feel about you. +
+You are the light of my life
++ You complete my darkness with your light. I love: +
+-
+
+ I have learned a lot from you. You have occupied a special place in my heart over the time. +
+I have a confession to make
++ It feels like my chest does have a heart. You make my heart beat. Your smile brings smile on my face, your pain brings pain to my heart. +
++ I don't show my emotions, but I think this man behind the mask is falling for you. +
+I love you Superman.
+
+ Your not-so-secret-lover,
+ Batman
+
`：用于段落
+ * `
`：用于换行
+ * `
- `、`