Idea
+
+## Implementation
+```
+
+我们现在有一个顶级幻灯片（`＃Wine Management System`），其中包含两张幻灯片（`## Idea` 和 `## Implementation`）。
+
+通过创建一个由符号 `>` 开头的 Markdown 列表，在这两张幻灯片中添加一些内容。在上面代码的基础上，在第一张幻灯片中添加两个项目（第 9-10 行），第二张幻灯片中添加五个项目（第 16-20 行）：
+
+```
+% Case Study
+% Kiko Fernandez Reyes
+% Sept 27, 2017
+
+# Wine Management System
+
+## 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 this id in our embedded style as a selector: - -``` -#letter-container{ - ... -} -``` - -Notice the “#” symbol. It indicates that it is an id, and the styles inside {…} should apply to the element with that specific id only. - -Let’s apply this to our code: - -``` - -``` - -``` ---``` - -Our HTML is ready with embedded styling. - -However, you can see that as we include more styles, the will get bigger. This can quickly clutter our main html file. So let’s go one step further and use linked styling by copying the content inside our style tag to a new file. - -Create a new file in the project root directory and save it as style.css: - -``` -#letter-container{ - width:550px; -} -#header-bat-logo{ - width:100%; -} -``` - -We don’t need to write `` in our CSS file. - -We need to link our newly created CSS file to our HTML file using the ``tag in our html file. Here’s how we can do that: - -``` - -``` - -We use the link element to include external resources inside your HTML document. It is mostly used to link Stylesheets. The three attributes that we are using are: - -* rel: Relation. What relationship the linked file has to the document. The file with the .css extension is called a stylesheet, and so we keep rel=“stylesheet”. - -* type: the Type of the linked file; it’s “text/css” for a CSS file. - -* href: Hypertext Reference. Location of the linked file. - -There is no at the end of the link element. So, is also a self-closing tag. - -``` - -``` - -If only getting a Girlfriend was so easy :D - -Nah, that’s not gonna happen, let’s move on. - -Here’s the content of our loveletter.html: - -``` - -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 our style.css: - -``` -#letter-container{ - width:550px; -} -#header-bat-logo{ - width:100%; -} -``` - -Save both the files and refresh, and your output in the browser should remain the same. - -### A Few Formalities - -Our love letter is almost ready to deliver to Batman, but there are a few formal pieces remaining. - -Like any other programming language, HTML has also gone through many versions since its birth year(1990). The current version of HTML is HTML5. - -So, how would the browser know which version of HTML you are using to code your page? To tell the browser that you are using HTML5, you need to include `` at top of the page. For older versions of HTML, this line used to be different, but you don’t need to learn that because we don’t use them anymore. - -Also, in previous HTML versions, we used to encapsulate the entire document inside `` tag. The entire file was divided into two major sections: Head, inside ``, and Body, inside ``. This is not required in HTML5, but we still do this for compatibility reasons. Let’s update our code with `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 ``: - -``` - - - - - - - -- - -``` - -The main content goes inside `` and meta information goes inside ``. So we keep the div inside `` and load the stylesheets inside ``. - -Save and refresh, and your HTML page should display the same as earlier. - -### Title in HTML - -This is the last change. I promise. - -You might have noticed that the title of the tab is displaying the path of the HTML file: - - - - -We can use `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 -` tag to define a title for our HTML file. The title tag also, like the link tag, goes inside head. Let’s put “Bat Letter” in our title: - -``` -<!DOCTYPE html> -<html> -<head> - <title>Bat Letter - - - --- - -``` - -Save and refresh, and you will see that instead of the file path, “Bat Letter” is now displayed on the tab. - -Batman’s Love Letter is now complete. - -Congratulations! You made Batman’s Love Letter in HTML. - - - - -### What we learned - -We learned the following new concepts: - -* The structure of an HTML document - -* How to write elements in HTML () - -* How to write styles inside the element using the style attribute (this is called inline styling, avoid this as much as you can) - -* How to write styles of an element inside (this is called embedded styling) - -* How to write styles in a separate file and link to it in HTML using (this is called a linked stylesheet) - -* What is a tag name, attribute, opening tag, and closing tag - -* How to give an id to an element using id attribute - -* Tag selectors and id selectors in CSS - -We learned the following HTML tags: - -*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 -: for paragraphs - -*
: for line breaks - -*- ,
- : to display lists
-
-* : for grouping elements of our letter - -*
,
: for heading and sub heading - -*
: to insert an image - -* , : for bold and italic text styling - -* +
+
+ + + ++ +
+
+
++``` + +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/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/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 Midori- A Lightweight Open Source Web Browser.md b/sources/tech/20190104 Midori- A Lightweight Open Source Web Browser.md new file mode 100644 index 0000000000..fa1bd9c2c2 --- /dev/null +++ b/sources/tech/20190104 Midori- A Lightweight Open Source Web Browser.md @@ -0,0 +1,110 @@ +[#]: collector: (lujun9972) +[#]: translator: (geekpi) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Midori: A Lightweight Open Source Web Browser) +[#]: via: (https://itsfoss.com/midori-browser) +[#]: author: (Abhishek Prakash https://itsfoss.com/author/abhishek/) + +Midori: A Lightweight Open Source Web Browser +====== + +**Here’s a quick review of the lightweight, fast, open source web browser Midori, which has returned from the dead.** + +If you are looking for a lightweight [alternative web browser][1], try Midori. + +[Midori][2] is an open source web browser that focuses more on being lightweight than on providing a ton of features. + +If you have never heard of Midori, you might think that it is a new application but Midori was first released in 2007. + +Because it focused on speed, Midori soon gathered a niche following and became the default browser in lightweight Linux distributions like Bodhi Linux, SilTaz etc. + +Other distributions like [elementary OS][3] also used Midori as its default browser. But the development of Midori stalled around 2016 and its fans started wondering if Midori was dead already. elementary OS dropped it from its latest release, I believe, for this reason. + +The good news is that Midori is not dead. After almost two years of inactivity, the development resumed in the last quarter of 2018. A few extensions including an ad-blocker were added in the later releases. + +### Features of Midori web browser + +![Midori web browser][4] + +Here are some of the main features of the Midori browser + + * Written in Vala with GTK+3 and WebKit rendering engine. + * Tabs, windows and session management + * Speed dial + * Saves tab for the next session by default + * Uses DuckDuckGo as a default search engine. It can be changed to Google or Yahoo. + * Bookmark management + * Customizable and extensible interface + * Extension modules can be written in C and Vala + * Supports HTML5 + * An extremely limited set of extensions include an ad-blocker, colorful tabs etc. No third-party extensions. + * Form history + * Private browsing + * Available for Linux and Windows + + + +Trivia: Midori is a Japanese word that means green. The Midori developer is not Japanese if you were guessing something along that line. + +### Experiencing Midori + +![Midori web browser in Ubuntu 18.04][5] + +I have been using Midori for the past few days. The experience is mostly fine. It supports HTML5 and renders the websites quickly. The ad-blocker is okay. The browsing experience is more or less smooth as you would expect in any standard web browser. + +The lack of extensions has always been a weak point of Midori so I am not going to talk about that. + +What I did notice is that it doesn’t support international languages. I couldn’t find a way to add new language support. It could not render the Hindi fonts at all and I am guessing it’s the same with many other non-[Romance languages][6]. + +I also had my fair share of troubles with YouTube videos. Some videos would throw playback error while others would run just fine. + +Midori didn’t eat my RAM like Chrome so that’s a big plus here. + +If you want to try out Midori, let’s see how can you get your hands on it. + +### Install Midori on Linux + +Midori is no longer available in the Ubuntu 18.04 repository. However, the newer versions of Midori can be easily installed using the [Snap packages][7]. + +If you are using Ubuntu, you can find Midori (Snap version) in the Software Center and install it from there. + +![Midori browser is available in Ubuntu Software Center][8]Midori browser is available in Ubuntu Software Center + +For other Linux distributions, make sure that you have [Snap support enabled][9] and then you can install Midori using the command below: + +``` +sudo snap install midori +``` + +You always have the option to compile from the source code. You can download the source code of Midori from its website. + +If you like Midori and want to help this open source project, please donate to them or [buy Midori merchandise from their shop][10]. + +Do you use Midori or have you ever tried it? How’s your experience with it? What other web browser do you prefer to use? Please share your views in the comment section below. + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/midori-browser + +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://itsfoss.com/open-source-browsers-linux/ +[2]: https://www.midori-browser.org/ +[3]: https://itsfoss.com/elementary-os-juno-features/ +[4]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/Midori-web-browser.jpeg?resize=800%2C450&ssl=1 +[5]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/01/midori-browser-linux.jpeg?resize=800%2C491&ssl=1 +[6]: https://en.wikipedia.org/wiki/Romance_languages +[7]: https://itsfoss.com/use-snap-packages-ubuntu-16-04/ +[8]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/midori-ubuntu-software-center.jpeg?ssl=1 +[9]: https://itsfoss.com/install-snap-linux/ +[10]: https://www.midori-browser.org/shop +[11]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/Midori-web-browser.jpeg?fit=800%2C450&ssl=1 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/20190104 Take to the virtual skies with FlightGear.md b/sources/tech/20190104 Take to the virtual skies with FlightGear.md new file mode 100644 index 0000000000..c3793e4128 --- /dev/null +++ b/sources/tech/20190104 Take to the virtual skies with FlightGear.md @@ -0,0 +1,93 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Take to the virtual skies with FlightGear) +[#]: via: (https://opensource.com/article/19/1/flightgear) +[#]: author: (Don Watkins https://opensource.com/users/don-watkins) + +Take to the virtual skies with FlightGear +====== +Dreaming of piloting a plane? Try open source flight simulator FlightGear. + + +If you've ever dreamed of piloting a plane, you'll love [FlightGear][1]. It's a full-featured, [open source][2] flight simulator that runs on Linux, MacOS, and Windows. + +The FlightGear project began in 1996 due to dissatisfaction with commercial flight simulation programs, which were not scalable. Its goal was to create a sophisticated, robust, extensible, and open flight simulator framework for use in academia and pilot training or by anyone who wants to play with a flight simulation scenario. + +### Getting started + +FlightGear's hardware requirements are fairly modest, including an accelerated 3D video card that supports OpenGL for smooth framerates. It runs well on my Linux laptop with an i5 processor and only 4GB of RAM. Its documentation includes an [online manual][3]; a [wiki][4] with portals for [users][5] and [developers][6]; and extensive tutorials (such as one for its default aircraft, the [Cessna 172p][7]) to teach you how to operate it. + +It's easy to install on both [Fedora][8] and [Ubuntu][9] Linux. Fedora users can consult the [Fedora installation page][10] to get FlightGear running. + +On Ubuntu 18.04, I had to install a repository: + +``` +$ sudo add-apt-repository ppa:saiarcot895/flightgear +$ sudo apt-get update +$ sudo apt-get install flightgear +``` + +Once the installation finished, I launched it from the GUI, but you can also launch the application from a terminal by entering: + +``` +$ fgfs +``` + +### Configuring FlightGear + +The menu on the left side of the application window provides configuration options. + + + +**Summary** returns you to the application's home screen. + +**Aircraft** shows the aircraft you have installed and offers the option to install up to 539 other aircraft available in FlightGear's default "hangar." I installed a Cessna 150L, a Piper J-3 Cub, and a Bombardier CRJ-700. Some of the aircraft (including the CRJ-700) have tutorials to teach you how to fly a commercial jet; I found the tutorials informative and accurate. + + + +To select an aircraft to pilot, highlight it and click on **Fly!** at the bottom of the menu. I chose the default Cessna 172p and found the cockpit depiction extremely accurate. + + + +The default airport is Honolulu, but you can change it in the **Location** menu by providing your favorite airport's [ICAO airport code][11] identifier. I found some small, local, non-towered airports like Olean and Dunkirk, New York, as well as larger airports including Buffalo, O'Hare, and Raleigh—and could even choose a specific runway. + +Under **Environment** , you can adjust the time of day, the season, and the weather. The simulation includes advance weather modeling and the ability to download current weather from [NOAA][12]. + +**Settings** provides an option to start the simulation in Paused mode by default. Also in Settings, you can select multi-player mode, which allows you to "fly" with other players on FlightGear supporters' global network of servers that allow for multiple users. You must have a moderately fast internet connection to support this functionality. + +The **Add-ons** menu allows you to download aircraft and additional scenery. + +### Take flight + +To "fly" my Cessna, I used a Logitech joystick that worked well. You can calibrate your joystick using an option in the **File** menu at the top. + +Overall, I found the simulation very accurate and think the graphics are great. Try FlightGear yourself — I think you will find it a very fun and complete simulation package. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/flightgear + +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]: http://home.flightgear.org/ +[2]: http://wiki.flightgear.org/GNU_General_Public_License +[3]: http://flightgear.sourceforge.net/getstart-en/getstart-en.html +[4]: http://wiki.flightgear.org/FlightGear_Wiki +[5]: http://wiki.flightgear.org/Portal:User +[6]: http://wiki.flightgear.org/Portal:Developer +[7]: http://wiki.flightgear.org/Cessna_172P +[8]: http://rpmfind.net/linux/rpm2html/search.php?query=flightgear +[9]: https://launchpad.net/~saiarcot895/+archive/ubuntu/flightgear +[10]: https://apps.fedoraproject.org/packages/FlightGear/ +[11]: https://en.wikipedia.org/wiki/ICAO_airport_code +[12]: https://www.noaa.gov/ diff --git a/sources/tech/20190104 Three Ways To Reset And Change Forgotten Root Password on RHEL 7-CentOS 7 Systems.md b/sources/tech/20190104 Three Ways To Reset And Change Forgotten Root Password on RHEL 7-CentOS 7 Systems.md new file mode 100644 index 0000000000..6619cfe65a --- /dev/null +++ b/sources/tech/20190104 Three Ways To Reset And Change Forgotten Root Password on RHEL 7-CentOS 7 Systems.md @@ -0,0 +1,254 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Three Ways To Reset And Change Forgotten Root Password on RHEL 7/CentOS 7 Systems) +[#]: via: (https://www.2daygeek.com/linux-reset-change-forgotten-root-password-in-rhel-7-centos-7/) +[#]: author: (Prakash Subramanian https://www.2daygeek.com/author/prakash/) + +Three Ways To Reset And Change Forgotten Root Password on RHEL 7/CentOS 7 Systems +====== + +If you are forget to remember your root password for RHEL 7 and CentOS 7 systems and want to reset the forgotten root password? + +If so, don’t worry we are here to help you out on this. + +Navigate to the following link if you want to **[reset forgotten root password on RHEL 6/CentOS 6][1]**. + +This is generally happens when you use different password in vast environment or if you are not maintaining the proper inventory. + +Whatever it is. No issues, we will help you through this article. + +It can be done in many ways but we are going to show you the best three methods which we tried many times for our clients. + +In Linux servers there are three different users are available. These are, Normal User, System User and Super User. + +As everyone knows the Root user is known as super user in Linux and Administrator is in Windows. + +We can’t perform any major activity without root password so, make sure you should have the right root password when you perform any major tasks. + +If you don’t know or don’t have it, try to reset using one of the below method. + + * Reset Forgotten Root Password By Booting into Single User Mode using `rd.break` + * Reset Forgotten Root Password By Booting into Single User Mode using `init=/bin/bash` + * Reset Forgotten Root Password By Booting into Rescue Mode + + + +### Method-1: Reset Forgotten Root Password By Booting into Single User Mode + +Just follow the below procedure to reset the forgotten root password in RHEL 7/CentOS 7 systems. + +To do so, reboot your system and follow the instructions carefully. + +**`Step-1:`** Reboot your system and interrupt at the boot menu by hitting **`e`** key to modify the kernel arguments. +![][3] + +**`Step-2:`** In the GRUB options, find `linux16` word and add the `rd.break` word in the end of the file then press `Ctrl+x` or `F10` to boot into single user mode. +![][4] + +**`Step-3:`** At this point of time, your root filesystem will be mounted in Read only (RO) mode to /sysroot. Run the below command to confirm this. + +``` +# mount | grep root +``` + +![][5] + +**`Step-4:`** Based on the above output, i can say that i’m in single user mode and my root file system is mounted in read only mode. + +It won’t allow you to make any changes on your system until you mount the root filesystem with Read and write (RW) mode to /sysroot. To do so, use the following command. + +``` +# mount -o remount,rw /sysroot +``` + +![][6] + +**`Step-5:`** Currently your file systems are mounted as a temporary partition. Now, your command prompt shows **switch_root:/#**. + +Run the following command to get into a chroot jail so that /sysroot is used as the root of the file system. + +``` +# chroot /sysroot +``` + +![][7] + +**`Step-6:`** Now you can able to reset the root password with help of `passwd` command. + +``` +# echo "CentOS7$#123" | passwd --stdin root +``` + +![][8] + +**`Step-7:`** By default CentOS 7/RHEL 7 use SELinux in enforcing mode, so create a following hidden file which will automatically perform a relabel of all files on next boot. + +It allow us to fix the context of the **/etc/shadow** file. + +``` +# touch /.autorelabel +``` + +![][9] + +**`Step-8:`** Issue `exit` twice to exit from the chroot jail environment and reboot the system. +![][10] + +**`Step-9:`** Now you can login to your system with your new password. +![][11] + +### Method-2: Reset Forgotten Root Password By Booting into Single User Mode + +Alternatively we can use the below procedure to reset the forgotten root password in RHEL 7/CentOS 7 systems. + +**`Step-1:`** Reboot your system and interrupt at the boot menu by hitting **`e`** key to modify the kernel arguments. +![][3] + +**`Step-2:`** In the GRUB options, find `rhgb quiet` word and replace with the `init=/bin/bash` or `init=/bin/sh` word then press `Ctrl+x` or `F10` to boot into single user mode. + +Screenshot for **`init=/bin/bash`**. +![][12] + +Screenshot for **`init=/bin/sh`**. +![][13] + +**`Step-3:`** At this point of time, your root system will be mounted in Read only mode to /. Run the below command to confirm this. + +``` +# mount | grep root +``` + +![][14] + +**`Step-4:`** Based on the above ouput, i can say that i’m in single user mode and my root file system is mounted in read only (RO) mode. + +It won’t allow you to make any changes on your system until you mount the root file system with Read and write (RW) mode. To do so, use the following command. + +``` +# mount -o remount,rw / +``` + +![][15] + +**`Step-5:`** Now you can able to reset the root password with help of `passwd` command. + +``` +# echo "RHEL7$#123" | passwd --stdin root +``` + +![][16] + +**`Step-6:`** By default CentOS 7/RHEL 7 use SELinux in enforcing mode, so create a following hidden file which will automatically perform a relabel of all files on next boot. + +It allow us to fix the context of the **/etc/shadow** file. + +``` +# touch /.autorelabel +``` + +![][17] + +**`Step-7:`** Finally `Reboot` the system. + +``` +# exec /sbin/init 6 +``` + +![][18] + +**`Step-9:`** Now you can login to your system with your new password. +![][11] + +### Method-3: Reset Forgotten Root Password By Booting into Rescue Mode + +Alternatively, we can reset the forgotten Root password for RHEL 7 and CentOS 7 systems using Rescue mode. + +**`Step-1:`** Insert the bootable media through USB or DVD drive which is compatible for you and reboot your system. It will take to you to the below screen. + +Hit `Troubleshooting` to launch the `Rescue` mode. +![][19] + +**`Step-2:`** Choose `Rescue a CentOS system` and hit `Enter` button. +![][20] + +**`Step-3:`** Here choose `1` and the rescue environment will now attempt to find your Linux installation and mount it under the directory `/mnt/sysimage`. +![][21] + +**`Step-4:`** Simple hit `Enter` to get a shell. +![][22] + +**`Step-5:`** Run the following command to get into a chroot jail so that /mnt/sysimage is used as the root of the file system. + +``` +# chroot /mnt/sysimage +``` + +![][23] + +**`Step-6:`** Now you can able to reset the root password with help of **passwd** command. + +``` +# echo "RHEL7$#123" | passwd --stdin root +``` + +![][24] + +**`Step-7:`** By default CentOS 7/RHEL 7 use SELinux in enforcing mode, so create a following hidden file which will automatically perform a relabel of all files on next boot. +It allow us to fix the context of the /etc/shadow file. + +``` +# touch /.autorelabel +``` + +![][25] + +**`Step-8:`** Remove the bootable media then initiate the reboot. + +**`Step-9:`** Issue `exit` twice to exit from the chroot jail environment and reboot the system. +![][26] + +**`Step-10:`** Now you can login to your system with your new password. +![][11] + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/linux-reset-change-forgotten-root-password-in-rhel-7-centos-7/ + +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/linux-reset-change-forgotten-root-password-in-rhel-6-centos-6/ +[2]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[3]: https://www.2daygeek.com/wp-content/uploads/2018/12/reset-forgotten-root-password-on-rhel-7-centos-7-2.png +[4]: https://www.2daygeek.com/wp-content/uploads/2018/12/reset-forgotten-root-password-on-rhel-7-centos-7-3.png +[5]: https://www.2daygeek.com/wp-content/uploads/2018/12/reset-forgotten-root-password-on-rhel-7-centos-7-5.png +[6]: https://www.2daygeek.com/wp-content/uploads/2018/12/reset-forgotten-root-password-on-rhel-7-centos-7-6.png +[7]: https://www.2daygeek.com/wp-content/uploads/2018/12/reset-forgotten-root-password-on-rhel-7-centos-7-8.png +[8]: https://www.2daygeek.com/wp-content/uploads/2018/12/reset-forgotten-root-password-on-rhel-7-centos-7-10.png +[9]: https://www.2daygeek.com/wp-content/uploads/2018/12/reset-forgotten-root-password-on-rhel-7-centos-7-10a.png +[10]: https://www.2daygeek.com/wp-content/uploads/2018/12/reset-forgotten-root-password-on-rhel-7-centos-7-11.png +[11]: https://www.2daygeek.com/wp-content/uploads/2018/12/reset-forgotten-root-password-on-rhel-7-centos-7-12.png +[12]: https://www.2daygeek.com/wp-content/uploads/2018/12/method-reset-forgotten-root-password-on-rhel-7-centos-7-1.png +[13]: https://www.2daygeek.com/wp-content/uploads/2018/12/method-reset-forgotten-root-password-on-rhel-7-centos-7-1a.png +[14]: https://www.2daygeek.com/wp-content/uploads/2018/12/method-reset-forgotten-root-password-on-rhel-7-centos-7-3.png +[15]: https://www.2daygeek.com/wp-content/uploads/2018/12/method-reset-forgotten-root-password-on-rhel-7-centos-7-4.png +[16]: https://www.2daygeek.com/wp-content/uploads/2018/12/method-reset-forgotten-root-password-on-rhel-7-centos-7-5.png +[17]: https://www.2daygeek.com/wp-content/uploads/2018/12/method-reset-forgotten-root-password-on-rhel-7-centos-7-6.png +[18]: https://www.2daygeek.com/wp-content/uploads/2018/12/method-reset-forgotten-root-password-on-rhel-7-centos-7-7.png +[19]: https://www.2daygeek.com/wp-content/uploads/2018/12/rescue-reset-forgotten-root-password-on-rhel-7-centos-7-1.png +[20]: https://www.2daygeek.com/wp-content/uploads/2018/12/rescue-reset-forgotten-root-password-on-rhel-7-centos-7-2.png +[21]: https://www.2daygeek.com/wp-content/uploads/2018/12/rescue-reset-forgotten-root-password-on-rhel-7-centos-7-3.png +[22]: https://www.2daygeek.com/wp-content/uploads/2018/12/rescue-reset-forgotten-root-password-on-rhel-7-centos-7-4.png +[23]: https://www.2daygeek.com/wp-content/uploads/2018/12/rescue-reset-forgotten-root-password-on-rhel-7-centos-7-5.png +[24]: https://www.2daygeek.com/wp-content/uploads/2018/12/rescue-reset-forgotten-root-password-on-rhel-7-centos-7-6.png +[25]: https://www.2daygeek.com/wp-content/uploads/2018/12/rescue-reset-forgotten-root-password-on-rhel-7-centos-7-7.png +[26]: https://www.2daygeek.com/wp-content/uploads/2018/12/rescue-reset-forgotten-root-password-on-rhel-7-centos-7-8.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 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/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/+ +mysql +mysql-arch.example.com +3306 +kodi +kodi ++ +true +true ++ + +1 +322122547 +20 +**. 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/20190115 Linux Desktop Setup - HookRace Blog.md b/sources/tech/20190115 Linux Desktop Setup - HookRace Blog.md new file mode 100644 index 0000000000..29d5f63d2a --- /dev/null +++ b/sources/tech/20190115 Linux Desktop Setup - HookRace Blog.md @@ -0,0 +1,514 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Linux Desktop Setup · HookRace Blog) +[#]: via: (https://hookrace.net/blog/linux-desktop-setup/) +[#]: author: (Dennis Felsing http://felsin9.de/nnis/) + +Linux Desktop Setup +====== + + +My software setup has been surprisingly constant over the last decade, after a few years of experimentation since I initially switched to Linux in 2006. It might be interesting to look back in another 10 years and see what changed. A quick overview of what’s running as I’m writing this post: + +[![htop overview][1]][2] + +### Motivation + +My software priorities are, in no specific order: + + * Programs should run on my local system so that I’m in control of them, this excludes cloud solutions. + * Programs should run in the terminal, so that they can be used consistently from anywhere, including weak computers or a phone. + * Keyboard focused is nearly automatic by using terminal software. I prefer to use the mouse where it makes sense only, reaching for the mouse all the time during typing feels like a waste of time. Occasionally it took me an hour to notice that the mouse wasn’t even plugged in. + * Ideally use fast and efficient software, I don’t like hearing the fan and feeling the room heat up. I can also keep running older hardware for much longer, my 10 year old Thinkpad x200s is still fine for all the software I use. + * Be composable. I don’t want to do every step manually, instead automate more when it makes sense. This naturally favors the shell. + + + +### Operating Systems + +I had a hard start with Linux 12 years ago by removing Windows, armed with just the [Gentoo Linux][3] installation CD and a printed manual to get a functioning Linux system. It took me a few days of compiling and tinkering, but in the end I felt like I had learnt a lot. + +I haven’t looked back to Windows since then, but I switched to [Arch Linux][4] on my laptop after having the fan fail from the constant compilation stress. Later I also switched all my other computers and private servers to Arch Linux. As a rolling release distribution you get package upgrades all the time, but the most important breakages are nicely reported in the [Arch Linux News][5]. + +One annoyance though is that Arch Linux removes the old kernel modules once you upgrade it. I usually notice that once I try plugging in a USB flash drive and the kernel fails to load the relevant module. Instead you’re supposed to reboot after each kernel upgrade. There are a few [hacks][6] around to get around the problem, but I haven’t been bothered enough to actually use them. + +Similar problems happen with other programs, commonly Firefox, cron or Samba requiring a restart after an upgrade, but annoyingly not warning you that that’s the case. [SUSE][7], which I use at work, nicely warns about such cases. + +For the [DDNet][8] production servers I prefer [Debian][9] over Arch Linux, so that I have a lower chance of breakage on each upgrade. For my firewall and router I used [OpenBSD][10] for its clean system, documentation and great [pf firewall][11], but right now I don’t have a need for a separate router anymore. + +### Window Manager + +Since I started out with Gentoo I quickly noticed the huge compile time of KDE, which made it a no-go for me. I looked around for more minimal solutions, and used [Openbox][12] and [Fluxbox][13] initially. At some point I jumped on the tiling window manager train in order to be more keyboard-focused and picked up [dwm][14] and [awesome][15] close to their initial releases. + +In the end I settled on [xmonad][16] thanks to its flexibility, extendability and being written and configured in pure [Haskell][17], a great functional programming language. One example of this is that at home I run a single 40” 4K screen, but often split it up into four virtual screens, each displaying a workspace on which my windows are automatically arranged. Of course xmonad has a [module][18] for that. + +[dzen][19] and [conky][20] function as a simple enough status bar for me. My entire conky config looks like this: + +``` +out_to_console yes +update_interval 1 +total_run_times 0 + +TEXT +${downspeed eth0} ${upspeed eth0} | $cpu% ${loadavg 1} ${loadavg 2} ${loadavg 3} $mem/$memmax | ${time %F %T} +``` + +And gets piped straight into dzen2 with `conky | dzen2 -fn '-xos4-terminus-medium-r-normal-*-12-*-*-*-*-*-*-*' -bg '#000000' -fg '#ffffff' -p -e '' -x 1000 -w 920 -xs 1 -ta r`. + +One important feature for me is to make the terminal emit a beep sound once a job is done. This is done simply by adding a `\a` character to the `PR_TITLEBAR` variable in zsh, which is shown whenever a job is done. Of course I disable the actual beep sound by blacklisting the `pcspkr` kernel module with `echo "blacklist pcspkr" > /etc/modprobe.d/nobeep.conf`. Instead the sound gets turned into an urgency by urxvt’s `URxvt.urgentOnBell: true` setting. Then xmonad has an urgency hook to capture this and I can automatically focus the currently urgent window with a key combination. In dzen I get the urgent windowspaces displayed with a nice and bright `#ff0000`. + +The final result in all its glory on my Laptop: + +[![Laptop screenshot][21]][22] + +I hear that [i3][23] has become quite popular in the last years, but it requires more manual window alignment instead of specifying automated methods to do it. + +I realize that there are also terminal multiplexers like [tmux][24], but I still require a few graphical applications, so in the end I never used them productively. + +### Terminal Persistency + +In order to keep terminals alive I use [dtach][25], which is just the detach feature of screen. In order to make every terminal on my computer detachable I wrote a [small wrapper script][26]. This means that even if I had to restart my X server I could keep all my terminals running just fine, both local and remote. + +### Shell & Programming + +Instead of [bash][27] I use [zsh][28] as my shell for its huge number of features. + +As a terminal emulator I found [urxvt][29] to be simple enough, support Unicode and 256 colors and has great performance. Another great feature is being able to run the urxvt client and daemon separately, so that even a large number of terminals barely takes up any memory (except for the scrollback buffer). + +There is only one font that looks absolutely clean and perfect to me: [Terminus][30]. Since i’s a bitmap font everything is pixel perfect and renders extremely fast and at low CPU usage. In order to switch fonts on-demand in each terminal with `CTRL-WIN-[1-7]` my ~/.Xdefaults contains: + +``` +URxvt.font: -xos4-terminus-medium-r-normal-*-14-*-*-*-*-*-*-* +dzen2.font: -xos4-terminus-medium-r-normal-*-14-*-*-*-*-*-*-* + +URxvt.keysym.C-M-1: command:\033]50;-xos4-terminus-medium-r-normal-*-12-*-*-*-*-*-*-*\007 +URxvt.keysym.C-M-2: command:\033]50;-xos4-terminus-medium-r-normal-*-14-*-*-*-*-*-*-*\007 +URxvt.keysym.C-M-3: command:\033]50;-xos4-terminus-medium-r-normal-*-18-*-*-*-*-*-*-*\007 +URxvt.keysym.C-M-4: command:\033]50;-xos4-terminus-medium-r-normal-*-22-*-*-*-*-*-*-*\007 +URxvt.keysym.C-M-5: command:\033]50;-xos4-terminus-medium-r-normal-*-24-*-*-*-*-*-*-*\007 +URxvt.keysym.C-M-6: command:\033]50;-xos4-terminus-medium-r-normal-*-28-*-*-*-*-*-*-*\007 +URxvt.keysym.C-M-7: command:\033]50;-xos4-terminus-medium-r-normal-*-32-*-*-*-*-*-*-*\007 + +URxvt.keysym.C-M-n: command:\033]10;#ffffff\007\033]11;#000000\007\033]12;#ffffff\007\033]706;#00ffff\007\033]707;#ffff00\007 +URxvt.keysym.C-M-b: command:\033]10;#000000\007\033]11;#ffffff\007\033]12;#000000\007\033]706;#0000ff\007\033]707;#ff0000\007 +``` + +For programming and writing I use [Vim][31] with syntax highlighting and [ctags][32] for indexing, as well as a few terminal windows with grep, sed and the other usual suspects for search and manipulation. This is probably not at the same level of comfort as an IDE, but allows me more automation. + +One problem with Vim is that you get so used to its key mappings that you’ll want to use them everywhere. + +[Python][33] and [Nim][34] do well as scripting languages where the shell is not powerful enough. + +### System Monitoring + +[htop][35] (look at the background of that site, it’s a live view of the server that’s hosting it) works great for getting a quick overview of what the software is currently doing. [lm_sensors][36] allows monitoring the hardware temperatures, fans and voltages. [powertop][37] is a great little tool by Intel to find power savings. [ncdu][38] lets you analyze disk usage interactively. + +[nmap][39], iptraf-ng, [tcpdump][40] and [Wireshark][41] are essential tools for analyzing network problems. + +There are of course many more great tools. + +### Mails & Synchronization + +On my home server I have a [fetchmail][42] daemon running for each email acccount that I have. Fetchmail just retrieves the incoming emails and invokes [procmail][43]: + +``` +#!/bin/sh +for i in /home/deen/.fetchmail/*; do + FETCHMAILHOME=$i /usr/bin/fetchmail -m 'procmail -d %T' -d 60 +done +``` + +The configuration is as simple as it could be and waits for the server to inform us of fresh emails: + +``` +poll imap.1und1.de protocol imap timeout 120 user "dennis@felsin9.de" password "XXX" folders INBOX keep ssl idle +``` + +My `.procmailrc` config contains a few rules to backup all mails and sort them into the correct directories, for example based on the mailing list id or from field in the mail header: + +``` +MAILDIR=/home/deen/shared/Maildir +LOGFILE=$HOME/.procmaillog +LOGABSTRACT=no +VERBOSE=off +FORMAIL=/usr/bin/formail +NL=" +" + +:0wc +* ! ? test -d /media/mailarchive/`date +%Y` +| mkdir -p /media/mailarchive/`date +%Y` + +# Make backups of all mail received in format YYYY/YYYY-MM +:0c +/media/mailarchive/`date +%Y`/`date +%Y-%m` + +:0 +* ^From: .*(.*@.*.kit.edu|.*@.*.uka.de|.*@.*.uni-karlsruhe.de) +$MAILDIR/.uni/ + +:0 +* ^list-Id:.*lists.kit.edu +$MAILDIR/.uni-ml/ + +[...] +``` + +To send emails I use [msmtp][44], which is also great to configure: + +``` +account default +host smtp.1und1.de +tls on +tls_trust_file /etc/ssl/certs/ca-certificates.crt +auth on +from dennis@felsin9.de +user dennis@felsin9.de +password XXX + +[...] +``` + +But so far the emails are still on the server. My documents are all stored in a directory that I synchronize between all computers using [Unison][45]. Think of Unison as a bidirectional interactive [rsync][46]. My emails are part of this documents directory and thus they end up on my desktop computers. + +This also means that while the emails reach my server immediately, I only fetch them on deman instead of getting instant notifications when an email comes in. + +From there I read the mails with [mutt][47], using the sidebar plugin to display my mail directories. The `/etc/mailcap` file is essential to display non-plaintext mails containing HTML, Word or PDF: + +``` +text/html;w3m -I %{charset} -T text/html; copiousoutput +application/msword; antiword %s; copiousoutput +application/pdf; pdftotext -layout /dev/stdin -; copiousoutput +``` + +### News & Communication + +[Newsboat][48] is a nice little RSS/Atom feed reader in the terminal. I have it running on the server in a `tach` session with about 150 feeds. Filtering feeds locally is also possible, for example: + +``` +ignore-article "https://forum.ddnet.tw/feed.php" "title =~ \"Map Testing •\" or title =~ \"Old maps •\" or title =~ \"Map Bugs •\" or title =~ \"Archive •\" or title =~ \"Waiting for mapper •\" or title =~ \"Other mods •\" or title =~ \"Fixes •\"" +``` + +I use [Irssi][49] the same way for communication via IRC. + +### Calendar + +[remind][50] is a calendar that can be used from the command line. Setting new reminders is done by editing the `rem` files: + +``` +# One time events +REM 2019-01-20 +90 Flight to China %b + +# Recurring Holidays +REM 1 May +90 Holiday "Tag der Arbeit" %b +REM [trigger(easterdate(year(today()))-2)] +90 Holiday "Karfreitag" %b + +# Time Change +REM Nov Sunday 1 --7 +90 Time Change (03:00 -> 02:00) %b +REM Apr Sunday 1 --7 +90 Time Change (02:00 -> 03:00) %b + +# Birthdays +FSET birthday(x) "'s " + ord(year(trigdate())-x) + " birthday is %b" +REM 16 Apr +90 MSG Andreas[birthday(1994)] + +# Sun +SET $LatDeg 49 +SET $LatMin 19 +SET $LatSec 49 +SET $LongDeg -8 +SET $LongMin -40 +SET $LongSec -24 + +MSG Sun from [sunrise(trigdate())] to [sunset(trigdate())] +[...] +``` + +Unfortunately there is no Chinese Lunar calendar function in remind yet, so Chinese holidays can’t be calculated easily. + +I use two aliases for remind: + +``` +rem -m -b1 -q -g +``` + +to see a list of the next events in chronological order and + +``` +rem -m -b1 -q -cuc12 -w$(($(tput cols)+1)) | sed -e "s/\f//g" | less +``` + +to show a calendar fitting just the width of my terminal: + +![remcal][51] + +### Dictionary + +[rdictcc][52] is a little known dictionary tool that uses the excellent dictionary files from [dict.cc][53] and turns them into a local database: + +``` +$ rdictcc rasch +====================[ A => B ]==================== +rasch: + - apace + - brisk [speedy] + - cursory + - in a timely manner + - quick + - quickly + - rapid + - rapidly + - sharpish [Br.] [coll.] + - speedily + - speedy + - swift + - swiftly +rasch [gehen]: + - smartly [quickly] +Rasch {n} [Zittergras-Segge]: + - Alpine grass [Carex brizoides] + - quaking grass sedge [Carex brizoides] +Rasch {m} [regional] [Putzrasch]: + - scouring pad +====================[ B => A ]==================== +Rasch model: + - Rasch-Modell {n} +``` + +### Writing and Reading + +I have a simple todo file containing my tasks, that is basically always sitting open in a Vim session. For work I also use the todo file as a “done” file so that I can later check what tasks I finished on each day. + +For writing documents, letters and presentations I use [LaTeX][54] for its superior typesetting. A simple letter in German format can be set like this for example: + +``` +\documentclass[paper = a4, fromalign = right]{scrlttr2} +\usepackage{german} +\usepackage{eurosym} +\usepackage[utf8]{inputenc} +\setlength{\parskip}{6pt} +\setlength{\parindent}{0pt} + +\setkomavar{fromname}{Dennis Felsing} +\setkomavar{fromaddress}{Meine Str. 1\\69181 Leimen} +\setkomavar{subject}{Titel} + +\setkomavar*{enclseparator}{Anlagen} + +\makeatletter +\@setplength{refvpos}{89mm} +\makeatother + +\begin{document} +\begin{letter} {Herr Soundso\\Deine Str. 2\\69121 Heidelberg} +\opening{Sehr geehrter Herr Soundso,} + +Sie haben bei mir seit dem Bla Bla Bla. + +Ich fordere Sie hiermit zu Bla Bla Bla auf. + +\closing{Mit freundlichen Grüßen} + +\end{letter} +\end{document} +``` + +Further example documents and presentations can be found over at [my private site][55]. + +To read PDFs [Zathura][56] is fast, has Vim-like controls and even supports two different PDF backends: Poppler and MuPDF. [Evince][57] on the other hand is more full-featured for the cases where I encounter documents that Zathura doesn’t like. + +### Graphical Editing + +[GIMP][58] and [Inkscape][59] are easy choices for photo editing and interactive vector graphics respectively. + +In some cases [Imagemagick][60] is good enough though and can be used straight from the command line and thus automated to edit images. Similarly [Graphviz][61] and [TikZ][62] can be used to draw graphs and other diagrams. + +### Web Browsing + +As a web browser I’ve always used [Firefox][63] for its extensibility and low resource usage compared to Chrome. + +Unfortunately the [Pentadactyl][64] extension development stopped after Firefox switched to Chrome-style extensions entirely, so I don’t have satisfying Vim-like controls in my browser anymore. + +### Media Players + +[mpv][65] with hardware decoding allows watching videos at 5% CPU load using the `vo=gpu` and `hwdec=vaapi` config settings. `audio-channels=2` in mpv seems to give me clearer downmixing to my stereo speakers / headphones than what PulseAudio does by default. A great little feature is exiting with `Shift-Q` instead of just `Q` to save the playback location. When watching with someone with another native tongue you can use `--secondary-sid=` to show two subtitles at once, the primary at the bottom, the secondary at the top of the screen + +My wirelss mouse can easily be made into a remote control with mpv with a small `~/.config/mpv/input.conf`: + +``` +MOUSE_BTN5 run "mixer" "pcm" "-2" +MOUSE_BTN6 run "mixer" "pcm" "+2" +MOUSE_BTN1 cycle sub-visibility +MOUSE_BTN7 add chapter -1 +MOUSE_BTN8 add chapter 1 +``` + +[youtube-dl][66] works great for watching videos hosted online, best quality can be achieved with `-f bestvideo+bestaudio/best --all-subs --embed-subs`. + +As a music player [MOC][67] hasn’t been actively developed for a while, but it’s still a simple player that plays every format conceivable, including the strangest Chiptune formats. In the AUR there is a [patch][68] adding PulseAudio support as well. Even with the CPU clocked down to 800 MHz MOC barely uses 1-2% of a single CPU core. + +![moc][69] + +My music collection sits on my home server so that I can access it from anywhere. It is mounted using [SSHFS][70] and automount in the `/etc/fstab/`: + +``` +root@server:/media/media /mnt/media fuse.sshfs noauto,x-systemd.automount,idmap=user,IdentityFile=/root/.ssh/id_rsa,allow_other,reconnect 0 0 +``` + +### Cross-Platform Building + +Linux is great to build packages for any major operating system except Linux itself! In the beginning I used [QEMU][71] to with an old Debian, Windows and Mac OS X VM to build for these platforms. + +Nowadays I switched to using chroot for the old Debian distribution (for maximum Linux compatibility), [MinGW][72] to cross-compile for Windows and [OSXCross][73] to cross-compile for Mac OS X. + +The script used to [build DDNet][74] as well as the [instructions for updating library builds][75] are based on this. + +### Backups + +As usual, we nearly forgot about backups. Even if this is the last chapter, it should not be an afterthought. + +I wrote [rrb][76] (reverse rsync backup) 10 years ago to wrap rsync so that I only need to give the backup server root SSH rights to the computers that it is backing up. Surprisingly rrb needed 0 changes in the last 10 years, even though I kept using it the entire time. + +The backups are stored straight on the filesystem. Incremental backups are implemented using hard links (`--link-dest`). A simple [config][77] defines how long backups are kept, which defaults to: + +``` +KEEP_RULES=( \ + 7 7 \ # One backup a day for the last 7 days + 31 8 \ # 8 more backups for the last month + 365 11 \ # 11 more backups for the last year +1825 4 \ # 4 more backups for the last 5 years +) +``` + +Since some of my computers don’t have a static IP / DNS entry and I still want to back them up using rrb I use a reverse SSH tunnel (as a systemd service) for them: + +``` +[Unit] +Description=Reverse SSH Tunnel +After=network.target + +[Service] +ExecStart=/usr/bin/ssh -N -R 27276:localhost:22 -o "ExitOnForwardFailure yes" server +KillMode=process +Restart=always + +[Install] +WantedBy=multi-user.target +``` + +Now the server can reach the client through `ssh -p 27276 localhost` while the tunnel is running to perform the backup, or in `.ssh/config` format: + +``` +Host cr-remote + HostName localhost + Port 27276 +``` + +While talking about SSH hacks, sometimes a server is not easily reachable thanks to some bad routing. In that case you can route the SSH connection through another server to get better routing, in this case going through the USA to reach my Chinese server which had not been reliably reachable from Germany for a few weeks: + +``` +Host chn.ddnet.tw + ProxyCommand ssh -q usa.ddnet.tw nc -q0 chn.ddnet.tw 22 + Port 22 +``` + +### Final Remarks + +Thanks for reading my random collection of tools. I probably forgot many programs that I use so naturally every day that I don’t even think about them anymore. Let’s see how stable my software setup stays in the next years. If you have any questions, feel free to get in touch with me at [dennis@felsin9.de][78]. + +Comments on [Hacker News][79]. + +-------------------------------------------------------------------------------- + +via: https://hookrace.net/blog/linux-desktop-setup/ + +作者：[Dennis Felsing][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://felsin9.de/nnis/ +[b]: https://github.com/lujun9972 +[1]: https://hookrace.net/public/linux-desktop/htop_small.png +[2]: https://hookrace.net/public/linux-desktop/htop.png +[3]: https://gentoo.org/ +[4]: https://www.archlinux.org/ +[5]: https://www.archlinux.org/news/ +[6]: https://www.reddit.com/r/archlinux/comments/4zrsc3/keep_your_system_fully_functional_after_a_kernel/ +[7]: https://www.suse.com/ +[8]: https://ddnet.tw/ +[9]: https://www.debian.org/ +[10]: https://www.openbsd.org/ +[11]: https://www.openbsd.org/faq/pf/ +[12]: http://openbox.org/wiki/Main_Page +[13]: http://fluxbox.org/ +[14]: https://dwm.suckless.org/ +[15]: https://awesomewm.org/ +[16]: https://xmonad.org/ +[17]: https://www.haskell.org/ +[18]: http://hackage.haskell.org/package/xmonad-contrib-0.15/docs/XMonad-Layout-LayoutScreens.html +[19]: http://robm.github.io/dzen/ +[20]: https://github.com/brndnmtthws/conky +[21]: https://hookrace.net/public/linux-desktop/laptop_small.png +[22]: https://hookrace.net/public/linux-desktop/laptop.png +[23]: https://i3wm.org/ +[24]: https://github.com/tmux/tmux/wiki +[25]: http://dtach.sourceforge.net/ +[26]: https://github.com/def-/tach/blob/master/tach +[27]: https://www.gnu.org/software/bash/ +[28]: http://www.zsh.org/ +[29]: http://software.schmorp.de/pkg/rxvt-unicode.html +[30]: http://terminus-font.sourceforge.net/ +[31]: https://www.vim.org/ +[32]: http://ctags.sourceforge.net/ +[33]: https://www.python.org/ +[34]: https://nim-lang.org/ +[35]: https://hisham.hm/htop/ +[36]: http://lm-sensors.org/ +[37]: https://01.org/powertop/ +[38]: https://dev.yorhel.nl/ncdu +[39]: https://nmap.org/ +[40]: https://www.tcpdump.org/ +[41]: https://www.wireshark.org/ +[42]: http://www.fetchmail.info/ +[43]: http://www.procmail.org/ +[44]: https://marlam.de/msmtp/ +[45]: https://www.cis.upenn.edu/~bcpierce/unison/ +[46]: https://rsync.samba.org/ +[47]: http://www.mutt.org/ +[48]: https://newsboat.org/ +[49]: https://irssi.org/ +[50]: https://www.roaringpenguin.com/products/remind +[51]: https://hookrace.net/public/linux-desktop/remcal.png +[52]: https://github.com/tsdh/rdictcc +[53]: https://www.dict.cc/ +[54]: https://www.latex-project.org/ +[55]: http://felsin9.de/nnis/research/ +[56]: https://pwmt.org/projects/zathura/ +[57]: https://wiki.gnome.org/Apps/Evince +[58]: https://www.gimp.org/ +[59]: https://inkscape.org/ +[60]: https://imagemagick.org/Usage/ +[61]: https://www.graphviz.org/ +[62]: https://sourceforge.net/projects/pgf/ +[63]: https://www.mozilla.org/en-US/firefox/new/ +[64]: https://github.com/5digits/dactyl +[65]: https://mpv.io/ +[66]: https://rg3.github.io/youtube-dl/ +[67]: http://moc.daper.net/ +[68]: https://aur.archlinux.org/packages/moc-pulse/ +[69]: https://hookrace.net/public/linux-desktop/moc.png +[70]: https://github.com/libfuse/sshfs +[71]: https://www.qemu.org/ +[72]: http://www.mingw.org/ +[73]: https://github.com/tpoechtrager/osxcross +[74]: https://github.com/ddnet/ddnet-scripts/blob/master/ddnet-release.sh +[75]: https://github.com/ddnet/ddnet-scripts/blob/master/ddnet-lib-update.sh +[76]: https://github.com/def-/rrb/blob/master/rrb +[77]: https://github.com/def-/rrb/blob/master/config.example +[78]: mailto:dennis@felsin9.de +[79]: https://news.ycombinator.com/item?id=18979731 diff --git a/sources/tech/20190116 Best Audio Editors For Linux.md b/sources/tech/20190116 Best Audio Editors For Linux.md new file mode 100644 index 0000000000..d588c886e2 --- /dev/null +++ b/sources/tech/20190116 Best Audio Editors For Linux.md @@ -0,0 +1,156 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Best Audio Editors For Linux) +[#]: via: (https://itsfoss.com/best-audio-editors-linux) +[#]: author: (Ankush Das https://itsfoss.com/author/ankush/) + +Best Audio Editors For Linux +====== + +You’ve got a lot of choices when it comes to audio editors for Linux. No matter whether you are a professional music producer or just learning to create awesome music, the audio editors will always come in handy. + +Well, for professional-grade usage, a [DAW][1] (Digital Audio Workstation) is always recommended. However, not everyone needs all the functionalities, so you should know about some of the most simple audio editors as well. + +In this article, we will talk about a couple of DAWs and basic audio editors which are available as **free and open source** solutions for Linux and (probably) for other operating systems. + +### Top Audio Editors for Linux + +![Best audio editors and DAW for Linux][2] + +We will not be focusing on all the functionalities that DAWs offer – but the basic audio editing capabilities. You may still consider this as the list of best DAW for Linux. + +**Installation instruction:** You will find all the mentioned audio editors or DAWs in your AppCenter or Software center. In case, you do not find them listed, please head to their official website for more information. + +#### 1\. Audacity + +![audacity audio editor][3] + +Audacity is one of the most basic yet a capable audio editor available for Linux. It is a free and open-source cross-platform tool. A lot of you must be already knowing about it. + +It has improved a lot when compared to the time when it started trending. I do recall that I utilized it to “try” making karaokes by removing the voice from an audio file. Well, you can still do it – but it depends. + +**Features:** + +It also supports plug-ins that include VST effects. Of course, you should not expect it to support VST Instruments. + + * Live audio recording through a microphone or a mixer + * Export/Import capability supporting multiple formats and multiple files at the same time + * Plugin support: LADSPA, LV2, Nyquist, VST and Audio Unit effect plug-ins + * Easy editing with cut, paste, delete and copy functions. + * Spectogram view mode for analyzing frequencies + + + +#### 2\. LMMS + +![][4] + +LMMS is a free and open source (cross-platform) digital audio workstation. It includes all the basic audio editing functionalities along with a lot of advanced features. + +You can mix sounds, arrange them, or create them using VST instruments. It does support them. Also, it comes baked in with some samples, presets, VST Instruments, and effects to get started. In addition, you also get a spectrum analyzer for some advanced audio editing. + +**Features:** + + * Note playback via MIDI + * VST Instrument support + * Native multi-sample support + * Built-in compressor, limiter, delay, reverb, distortion and bass enhancer + + + +#### 3\. Ardour + +![Ardour audio editor][5] + +Ardour is yet another free and open source digital audio workstation. If you have an audio interface, Ardour will support it. Of course, you can add unlimited multichannel tracks. The multichannel tracks can also be routed to different mixer tapes for the ease of editing and recording. + +You can also import a video to it and edit the audio to export the whole thing. It comes with a lot of built-in plugins and supports VST plugins as well. + +**Features:** + + * Non-linear editing + * Vertical window stacking for easy navigation + * Strip silence, push-pull trimming, Rhythm Ferret for transient and note onset-based editing + + + +#### 4\. Cecilia + +![cecilia audio editor][6] + +Cecilia is not an ordinary audio editor application. It is meant to be used by sound designers or if you are just in the process of becoming one. It is technically an audio signal processing environment. It lets you create ear-bending sound out of them. + +You get in-build modules and plugins for sound effects and synthesis. It is tailored for a specific use – if that is what you were looking for – look no further! + +**Features:** + + * Modules to achieve more (UltimateGrainer – A state-of-the-art granulation processing, RandomAccumulator – Variable speed recording accumulator, +UpDistoRes – Distortion with upsampling and resonant lowpass filter) + * Automatic Saving of modulations + + + +#### 5\. Mixxx + +![Mixxx audio DJ ][7] + +If you want to mix and record something while being able to have a virtual DJ tool, [Mixxx][8] would be a perfect tool. You get to know the BPM, key, and utilize the master sync feature to match the tempo and beats of a song. Also, do not forget that it is yet another free and open source application for Linux! + +It supports custom DJ equipment as well. So, if you have one or a MIDI – you can record your live mixes using this tool. + +**Features** + + * Broadcast and record DJ Mixes of your song + * Ability to connect your equipment and perform live + * Key detection and BPM detection + + + +#### 6\. Rosegarden + +![rosegarden audio editor][9] + +Rosegarden is yet another impressive audio editor for Linux which is free and open source. It is neither a fully featured DAW nor a basic audio editing tool. It is a mixture of both with some scaled down functionalities. + +I wouldn’t recommend this for professionals but if you have a home studio or just want to experiment, this would be one of the best audio editors for Linux to have installed. + +**Features:** + + * Music notation editing + * Recording, Mixing, and samples + + + +### Wrapping Up + +These are some of the best audio editors you could find out there for Linux. No matter whether you need a DAW, a cut-paste editing tool, or a basic mixing/recording audio editor, the above-mentioned tools should help you out. + +Did we miss any of your favorite? Let us know about it in the comments below. + + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/best-audio-editors-linux + +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://en.wikipedia.org/wiki/Digital_audio_workstation +[2]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/01/linux-audio-editors-800x450.jpeg?resize=800%2C450&ssl=1 +[3]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/audacity-audio-editor.jpg?fit=800%2C591&ssl=1 +[4]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/lmms-daw.jpg?fit=800%2C472&ssl=1 +[5]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/ardour-audio-editor.jpg?fit=800%2C639&ssl=1 +[6]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/01/cecilia.jpg?fit=800%2C510&ssl=1 +[7]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/01/mixxx.jpg?fit=800%2C486&ssl=1 +[8]: https://itsfoss.com/dj-mixxx-2/ +[9]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/rosegarden.jpg?fit=800%2C391&ssl=1 +[10]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/linux-audio-editors.jpeg?fit=800%2C450&ssl=1 diff --git a/sources/tech/20190116 GameHub - An Unified Library To Put All Games Under One Roof.md b/sources/tech/20190116 GameHub - An Unified Library To Put All Games Under One Roof.md new file mode 100644 index 0000000000..bdaae74b43 --- /dev/null +++ b/sources/tech/20190116 GameHub - An Unified Library To Put All Games Under One Roof.md @@ -0,0 +1,139 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (GameHub – An Unified Library To Put All Games Under One Roof) +[#]: via: (https://www.ostechnix.com/gamehub-an-unified-library-to-put-all-games-under-one-roof/) +[#]: author: (SK https://www.ostechnix.com/author/sk/) + +GameHub – An Unified Library To Put All Games Under One Roof +====== + + + +**GameHub** is an unified gaming library that allows you to view, install, run and remove games on GNU/Linux operating system. It supports both native and non-native games from various sources including Steam, GOG, Humble Bundle, and Humble Trove etc. The non-native games are supported by [Wine][1], Proton, [DOSBox][2], ScummVM and RetroArch. It also allows you to add custom emulators and download bonus content and DLCs for GOG games. Simply put, Gamehub is a frontend for Steam/GoG/Humblebundle/Retroarch. It can use steam technologies like Proton to run windows gog games. GameHub is free, open source gaming platform written in **Vala** using **GTK+3**. If you’re looking for a way to manage all games under one roof, GameHub might be a good choice. + +### Installing GameHub + +The author of GameHub has designed it specifically for elementary OS. So, you can install it on Debian, Ubuntu, elementary OS and other Ubuntu-derivatives using GameHub PPA. + +``` +$ sudo apt install --no-install-recommends software-properties-common +$ sudo add-apt-repository ppa:tkashkin/gamehub +$ sudo apt update +$ sudo apt install com.github.tkashkin.gamehub +``` + +GameHub is available in [**AUR**][3], so just install it on Arch Linux and its variants using any AUR helpers, for example [**YaY**][4]. + +``` +$ yay -S gamehub-git +``` + +It is also available as **AppImage** and **Flatpak** packages in [**releases page**][5]. + +If you prefer AppImage package, do the following: + +``` +$ wget https://github.com/tkashkin/GameHub/releases/download/0.12.1-91-dev/GameHub-bionic-0.12.1-91-dev-cd55bb5-x86_64.AppImage -O gamehub +``` + +Make it executable: + +``` +$ chmod +x gamehub +``` + +And, run GameHub using command: + +``` +$ ./gamehub +``` + +If you want to use Flatpak installer, run the following commands one by one. + +``` +$ git clone https://github.com/tkashkin/GameHub.git +$ cd GameHub +$ scripts/build.sh build_flatpak +``` + +### Put All Games Under One Roof + +Launch GameHub from menu or application launcher. At first launch, you will see the following welcome screen. + + + +As you can see in the above screenshot, you need to login to the given sources namely Steam, GoG or Humble Bundle. If you don’t have Steam client on your Linux system, you need to install it first to access your steam account. For GoG and Humble bundle sources, click on the icon to log in to the respective source. + +Once you logged in to your account(s), all games from the all sources can be visible on GameHub dashboard. + + + +You will see list of logged-in sources on the top left corner. To view the games from each source, just click on the respective icon. + +You can also switch between list view or grid view, sort the games by applying the filters and search games from the list in GameHub dashboard. + +#### Installing a game + +Click on the game of your choice from the list and click Install button. If the game is non-native, GameHub will automatically choose the compatibility layer (E.g Wine) that suits to run the game and install the selected game. As you see in the below screenshot, Indiana Jones game is not available for Linux platform. + + + +If it is a native game (i.e supports Linux), simply press the Install button. + +![][7] + +If you don’t want to install the game, just hit the **Download** button to save it in your games directory. It is also possible to add locally installed games to GameHub using the **Import** option. + + + +#### GameHub Settings + +GameHub Settings window can be launched by clicking on the four straight lines on top right corner. + +From Settings section, we can enable, disable and set various settings such as, + + * Switch between light/dark themes. + * Use Symbolic icons instead of colored icons for games. + * Switch to compact list. + * Enable/disable merging games from different sources. + * Enable/disable compatibility layers. + * Set games collection directory. The default directory for storing the collection is **$HOME/Games/_Collection**. + * Set games directories for each source. + * Add/remove emulators, + * And many. + + + +For more details, refer the project links given at the end of this guide. + +**Related read:** + +And, that’s all for now. Hope this helps. I will be soon here with another guide. Until then, stay tuned with OSTechNix. + +Cheers! + + + +-------------------------------------------------------------------------------- + +via: https://www.ostechnix.com/gamehub-an-unified-library-to-put-all-games-under-one-roof/ + +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/run-windows-games-softwares-ubuntu-16-04/ +[2]: https://www.ostechnix.com/how-to-run-ms-dos-games-and-programs-in-linux/ +[3]: https://aur.archlinux.org/packages/gamehub-git/ +[4]: https://www.ostechnix.com/yay-found-yet-another-reliable-aur-helper/ +[5]: https://github.com/tkashkin/GameHub/releases +[6]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[7]: http://www.ostechnix.com/wp-content/uploads/2019/01/gamehub4.png 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/20190117 Pyvoc - A Command line Dictionary And Vocabulary Building Tool.md b/sources/tech/20190117 Pyvoc - A Command line Dictionary And Vocabulary Building Tool.md new file mode 100644 index 0000000000..b0aa45d618 --- /dev/null +++ b/sources/tech/20190117 Pyvoc - A Command line Dictionary And Vocabulary Building Tool.md @@ -0,0 +1,239 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Pyvoc – A Command line Dictionary And Vocabulary Building Tool) +[#]: via: (https://www.ostechnix.com/pyvoc-a-command-line-dictionary-and-vocabulary-building-tool/) +[#]: author: (SK https://www.ostechnix.com/author/sk/) + +Pyvoc – A Command line Dictionary And Vocabulary Building Tool +====== + + + +Howdy! I have a good news for non-native English speakers. Now, you can improve your English vocabulary and find the meaning of English words, right from your Terminal. Say hello to **Pyvoc** , a cross-platform, open source, command line dictionary and vocabulary building tool written in **Python** programming language. Using this tool, you can brush up some English words meanings, test or improve your vocabulary skill or simply use it as a CLI dictionary on Unix-like operating systems. + +### Installing Pyvoc + +Since Pyvoc is written using Python language, you can install it using [**Pip3**][1] package manager. + +``` +$ pip3 install pyvoc +``` + +Once installed, run the following command to automatically create necessary configuration files in your $HOME directory. + +``` +$ pyvoc word +``` + +Sample output: + +``` +|Creating necessary config files +/getting api keys. please handle with care! +| + +word +Noun: single meaningful element of speech or writing +example: I don't like the word ‘unofficial’ + +Verb: express something spoken or written +example: he words his request in a particularly ironic way + +Interjection: used to express agreement or affirmation +example: Word, that's a good record, man +``` + +Done! Let us go ahead and brush the English skills. + +### Use Pyvoc as a command line Dictionary tool + +Pyvoc fetches the word meaning from **Oxford Dictionary API**. + +Let us say, you want to find the meaning of a word **‘digression’**. To do so, run: + +``` +$ pyvoc digression +``` + + + +See? Pyvoc not only displays the meaning of word **‘digression’** , but also an example sentence which shows how to use that word in practical. + +Let us see an another example. + +``` +$ pyvoc subterfuge +| + +subterfuge +Noun: deceit used in order to achieve one's goal +example: he had to use subterfuge and bluff on many occasions +``` + +It also shows the word classes as well. As you already know, English has four major **word classes** : + + 1. Nouns, + + 2. Verbs, + + 3. Adjectives, + + 4. Adverbs. + + + + +Take a look at the following example. + +``` +$ pyvoc welcome + / + +welcome +Noun: instance or manner of greeting someone +example: you will receive a warm welcome + +Interjection: used to greet someone in polite or friendly way +example: welcome to the Wildlife Park + +Verb: greet someone arriving in polite or friendly way +example: hotels should welcome guests in their own language + +Adjective: gladly received +example: I'm pleased to see you, lad—you're welcome +``` + +As you see in the above output, the word ‘welcome’ can be used as a verb, noun, adjective and interjection. Pyvoc has given example for each class. + +If you misspell a word, it will inform you to check the spelling of the given word. + +``` +$ pyvoc wlecome +\ +No definition found. Please check the spelling!! +``` + +Useful, isn’t it? + +### Create vocabulary groups + +A vocabulary group is nothing but a collection words added by the user. You can later revise or take quiz from these groups. 100 groups of 60 words are **reserved** for the user. + +To add a word (E.g **sporadic** ) to a group, just run: + +``` +$ pyvoc sporadic -a +- + +sporadic +Adjective: occurring at irregular intervals or only in few places +example: sporadic fighting broke out + + +writing to vocabulary group... +word added to group number 51 +``` + +As you can see, I didn’t provide any group number and pyvoc displayed the meaning of given word and automatically added that word to group number **51**. If you don’t provide the group number, Pyvoc will **incrementally add words** to groups **51-100**. + +Pyvoc also allows you to specify a group number if you want to. You can specify a group from 1-50 using **-g** option. For example, I am going to add a word to Vocabulary group 20 using the following command. + +``` +$ pyvoc discrete -a -g 20 + / + +discrete +Adjective: individually separate and distinct +example: speech sounds are produced as a continuous sound signal rather + than discrete units + +creating group Number 20... +writing to vocabulary group... +word added to group number 20 +``` + +See? The above command displays the meaning of ‘discrete’ word and adds it to the vocabulary group 20. If the group doesn’t exists, Pyvoc will create it and add the word. + +By default, Pyvoc includes three predefined vocabulary groups (101, 102, and 103). These custom groups has 800 words of each. All words in these groups are taken from **GRE** and **SAT** preparation websites. + +To view the user-generated groups, simply run: + +``` +$ pyvoc word -l + - + +word +Noun: single meaningful element of speech or writing +example: I don't like the word ‘unofficial’ + +Verb: express something spoken or written +example: he words his request in a particularly ironic way + +Interjection: used to express agreement or affirmation +example: Word, that's a good record, man + + +USER GROUPS +Group no. No. of words +20 1 + +DEFAULT GROUP +Group no. No. of words +51 1 +``` +``` + +``` + +As you see, I have created one group (20) including the default group (51). + +### Test and improve English vocabulary + +As I already said, you can use the Vocabulary groups to revise or take quiz from them. + +For instance, to revise the group no. **101** , use **-r** option like below. + +``` +$ pyvoc 101 -r +``` + +You can now revise the meaning of all words in the Vocabulary group 101 in random order. Just hit ENTER to go through next questions. Once done, hit **CTRL+C** to exit. + + + +Also, you take quiz from the existing groups to brush up your vocabulary. To do so, use **-q** option like below. + +``` +$ pyvoc 103 -q 50 +``` + +This command allows you to take quiz of 50 questions from vocabulary group 103. Choose the correct answer from the list by entering the appropriate number. You will get 1 point for every correct answer. The more you score the more your vocabulary skill will be. + + + +Pyvoc is in the early-development stage. I hope the developer will improve it and add more features in the days to come. + +As a non-native English speaker, I personally find it useful to test and learn new word meanings in my free time. If you’re a heavy command line user and wanted to quickly check the meaning of a word, Pyvoc is the right tool. You can also test your English Vocabulary at your free time to memorize and improve your English language skill. Give it a try. You won’t be disappointed. + +And, that’s all for now. Hope this was useful. More good stuffs to come. Stay tuned! + +Cheers! + + +-------------------------------------------------------------------------------- + +via: https://www.ostechnix.com/pyvoc-a-command-line-dictionary-and-vocabulary-building-tool/ + +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/manage-python-packages-using-pip/ diff --git a/sources/tech/20190118 Secure Email Service Tutanota Has a Desktop App Now.md b/sources/tech/20190118 Secure Email Service Tutanota Has a Desktop App Now.md new file mode 100644 index 0000000000..f56f1272f2 --- /dev/null +++ b/sources/tech/20190118 Secure Email Service Tutanota Has a Desktop App Now.md @@ -0,0 +1,119 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Secure Email Service Tutanota Has a Desktop App Now) +[#]: via: (https://itsfoss.com/tutanota-desktop) +[#]: author: (John Paul https://itsfoss.com/author/john/) + +Secure Email Service Tutanota Has a Desktop App Now +====== + +[Tutanota][1] recently [announced][2] the release of a desktop app for their email service. The beta is available for Linux, Windows, and macOS. + +### What is Tutanota? + +There are plenty of free, ad-supported email services available online. However, the majority of those email services are not exactly secure or privacy-minded. In this post-[Snowden][3] world, [Tutanota][4] offers a free, secure email service with a focus on privacy. + +Tutanota has a number of eye-catching features, such as: + + * End-to-end encrypted mailbox + * End-to-end encrypted address book + * Automatic end-to-end encrypted emails between users + * End-to-end encrypted emails to any email address with a shared password + * Secure password reset that gives Tutanota absolutely no access + * Strips IP addresses from emails sent and received + * The code that runs Tutanota is [open source][5] + * Two-factor authentication + * Focus on privacy + * Passwords are salted and hashed locally with Bcrypt + * Secure servers located in Germany + * TLS with support for PFS, DMARC, DKIM, DNSSEC, and DANE + * Full-text search of encrypted data executed locally + + + +![][6] +Tutanota on the web + +You can [sign up for an account for free][7]. You can also upgrade your account to get extra features, such as custom domains, custom domain login, domain rules, extra storage, and aliases. They also have accounts available for businesses. + +Tutanota is also available on mobile devices. In fact, it’s [Android app is open source as well][8]. + +This German company is planning to expand beyond email. They hope to offer an encrypted calendar and cloud storage. You can help them reach their goals by [donating][9] via PayPal and cryptocurrency. + +### The New Desktop App from Tutanota + +Tutanota announced the [beta release][2] of the desktop app right before Christmas. They based this app on [Electron][10]. + +![][11] +Tutanota desktop app + +They went the Electron route: + + * to support all three major operating systems with minimum effort. + * to quickly adapt the new desktop clients so that they match new features added to the webmail client. + * to allocate development time to particular desktop features, e.g. offline availability, email import, that will simultaneously be available in all three desktop clients. + + + +Because this is a beta, there are several features missing from the app. The development team at Tutanota is working to add the following features: + + * Email import and synchronization with external mailboxes. This will “enable Tutanota to import emails from external mailboxes and encrypt the data locally on your device before storing it on the Tutanota servers.” + * Offline availability of emails + * Two-factor authentication + + + +### How to Install the Tutanota desktop client? + +![][12]Composing email in Tutanota + +You can [download][2] the beta app directly from Tutanota’s website. They have an [AppImage file for Linux][13], a .exe file for Windows, and a .app file for macOS. You can post any bugs that you encounter to the Tutanota [GitHub account][14]. + +To prove the security of the app, Tutanota signed each version. “The signatures make sure that the desktop clients as well as any updates come directly from us and have not been tampered with.” You can verify the signature using from Tutanota’s [GitHub page][15]. + +Remember, you will need to create a Tutanota account before you can use it. This is email client is designed to work solely with Tutanota. + +### Wrapping up + +I tested out the Tutanota email app on Linux Mint MATE. As to be expected, it was a mirror image of the web app. At this point in time, I don’t see any difference between the desktop app and the web app. The only use case that I can see to use the app now is to have Tutanota in its own window. + +Have you ever used [Tutanota][16]? If not, what is your favorite privacy conscience email service? Let us know in the comments below. + +If you found this article interesting, please take a minute to share it on social media, Hacker News or [Reddit][17]. + +![][18] + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/tutanota-desktop + +作者：[John Paul][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/john/ +[b]: https://github.com/lujun9972 +[1]: https://itsfoss.com/tutanota-review/ +[2]: https://tutanota.com/blog/posts/desktop-clients/ +[3]: https://en.wikipedia.org/wiki/Edward_Snowden +[4]: https://tutanota.com/ +[5]: https://tutanota.com/blog/posts/open-source-email +[6]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/12/tutanota2.jpg?resize=800%2C490&ssl=1 +[7]: https://tutanota.com/pricing +[8]: https://itsfoss.com/tutanota-fdroid-release/ +[9]: https://tutanota.com/community +[10]: https://electronjs.org/ +[11]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/01/tutanota-app1.png?fit=800%2C486&ssl=1 +[12]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/12/tutanota1.jpg?resize=800%2C405&ssl=1 +[13]: https://itsfoss.com/use-appimage-linux/ +[14]: https://github.com/tutao/tutanota +[15]: https://github.com/tutao/tutanota/blob/master/buildSrc/installerSigner.js +[16]: https://tutanota.com/polo/ +[17]: http://reddit.com/r/linuxusersgroup +[18]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2018/02/tutanota-featured.png?fit=800%2C450&ssl=1 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 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/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/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 | Push 4 onto the stack | +| * | Multiply to get 24 | +| 5 | Push 5 onto the stack | +| * | Multiply to get 120 | + +Note that the multiplication happens as soon as you type *****. If you hit **< enter>** after ***** , Orpie will duplicate the value at position 1 on the stack. (If this happens, you can drop the duplicate with **\**.) + +Equivalent sequences are: + +| Keys | Result | +| ------------- | ------------- | +| 2 3 * 4 * 5 * | Faster! | +| 2 3 4 5 * * * | Same result | +| 5 ' fact | Fastest: Use the built-in function | + +Observe that when you enter **'** , the left pane changes to show matching functions as you type. In the example above, typing **fa** is enough to get the **fact** function. Orpie offers many functions—experiment by typing **'** and a few letters to see what's available. + + + +Note that each operation replaces one or more values on the stack. If you want to store the value at position 1 in the stack, key in (for example) **@factot ** and **S'**. To retrieve the value, key in (for example) **@factot ** then **;** (if you want to see it; otherwise just leave **@factot** as the value for the next calculation). + +### Constants and units + +Orpie understands units and predefines many useful scientific constants. For example, to calculate the energy in a blue light photon at 400nm, calculate **E=hc/(400nm)**. The key sequences are: + +| Keys | Result | +| -------------- | -------------- | +| C c | Get the speed of light in m/s | +| C h | Get Planck's constant in Js | +| * | Calculate h*c | +| 400 9 n _ m | Input 4 _ 10^-9 m | +| / | Do the division and get the result: 4.966 _ 10^-19 J | + +Like choosing functions after typing **'** , typing **C** shows matching constants based on what you type. + + + +### Matrices + +Orpie can also do operations with matrices. For example, to multiply two 2x2 matrices: + +| Keys | Result | +| -------- | -------- | +| [ 1 , 2 [ 3 , 4 | Stack contains the matrix [[ 1, 2 ][ 3, 4 ]] | +| [ 1 , 0 [ 1 , 1 | Push the multiplier matrix onto the stack | +| * | The result is: [[ 3, 2 ][ 7, 4 ]] | + +Note that the **]** characters are automatically inserted—entering **[** starts a new row. + +### Complex numbers + +Orpie can also calculate with complex numbers. They can be entered or displayed in either polar or rectangular form. You can toggle between the polar and rectangular display using the **p** key, and between degrees and radians using the **r** key. For example, to multiply **3 + 4i** by **4 + 4i** : + +| Keys | Result | +| -------- | -------- | +| ( 3 , 4 | The stack contains (3, 4) | +| ( 4 , 4 | Push (4, 4) | +| * | Get the result: (-4, 28) | + +Note that as you go, the results are kept on the stack so you can observe intermediate results in a lengthy calculation. + + + +### Quitting Orpie + +You can exit from Orpie by typing **Q**. Your state is saved, so the next time you start Orpie, you'll find the stack as you left it. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/orpie + +作者：[Peter Faller][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/peterfaller +[b]: https://github.com/lujun9972 +[1]: https://en.wikipedia.org/wiki/Reverse_Polish_notation +[2]: https://github.com/pelzlpj/orpie/blob/master/doc/orpierc.5 diff --git a/sources/tech/20190124 What does DevOps mean to you.md b/sources/tech/20190124 What does DevOps mean to you.md new file mode 100644 index 0000000000..c62f0f83ba --- /dev/null +++ b/sources/tech/20190124 What does DevOps mean to you.md @@ -0,0 +1,143 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (What does DevOps mean to you?) +[#]: via: (https://opensource.com/article/19/1/what-does-devops-mean-you) +[#]: author: (Girish Managoli https://opensource.com/users/gammay) + +What does DevOps mean to you? +====== +6 experts break down DevOps and the practices and philosophies key to making it work. + + + +It's said if you ask 10 people about DevOps, you will get 12 answers. This is a result of the diversity in opinions and expectations around DevOps—not to mention the disparity in its practices. + +To decipher the paradoxes around DevOps, we went to the people who know it the best—its top practitioners around the industry. These are people who have been around the horn, who know the ins and outs of technology, and who have practiced DevOps for years. Their viewpoints should encourage, stimulate, and provoke your thoughts around DevOps. + +### What does DevOps mean to you? + +Let's start with the fundamentals. We're not looking for textbook answers, rather we want to know what the experts say. + +In short, the experts say DevOps is about principles, practices, and tools. + +[Ann Marie Fred][1], DevOps lead for IBM Digital Business Group's Commerce Platform, says, "to me, DevOps is a set of principles and practices designed to make teams more effective in designing, developing, delivering, and operating software." + +According to [Daniel Oh][2], senior DevOps evangelist at Red Hat, "in general, DevOps is compelling for enterprises to evolve current IT-based processes and tools related to app development, IT operations, and security protocol." + +[Brent Reed][3], founder of Tactec Strategic Solutions, talks about continuous improvement for the stakeholders. "DevOps means to me a way of working that includes a mindset that allows for continuous improvement for operational performance, maturing to organizational performance, resulting in delighted stakeholders." + +Many of the experts also emphasize culture. Ann Marie says, "it's also about continuous improvement and learning. It's about people and culture as much as it is about tools and technology." + +To [Dan Barker][4], chief architect and DevOps leader at the National Association of Insurance Commissioners (NAIC), "DevOps is primarily about culture. … It has brought several independent areas together like lean, [just culture][5], and continuous learning. And I see culture as being the most critical and the hardest to execute on." + +[Chris Baynham-Hughes][6], head of DevOps at Atos, says, "[DevOps] practice is adopted through the evolution of culture, process, and tooling within an organization. The key focus is culture change, and the key tenants of DevOps culture are collaboration, experimentation, fast-feedback, and continuous improvement." + +[Geoff Purdy][7], cloud architect, talks about agility and feedback "shortening and amplifying feedback loops. We want teams to get feedback in minutes rather than weeks." + +But in the end, Daniel nails it by explaining how open source and open culture allow him to achieve his goals "in easy and quick ways. In DevOps initiatives, the most important thing for me should be open culture rather than useful tools, multiple solutions." + +### What DevOps practices have you found effective? + +"Picking one, automated provisioning has been hugely effective for my team. " + +The most effective practices cited by the experts are pervasive yet disparate. + +According to Ann Marie, "some of the most powerful [practices] are agile project management; breaking down silos between cross-functional, autonomous squads; fully automated continuous delivery; green/blue deploys for zero downtime; developers setting up their own monitoring and alerting; blameless post-mortems; automating security and compliance." + +Chris says, "particular breakthroughs have been empathetic collaboration; continuous improvement; open leadership; reducing distance to the business; shifting from vertical silos to horizontal, cross-functional product teams; work visualization; impact mapping; Mobius loop; shortening of feedback loops; automation (from environments to CI/CD)." + +Brent supports "evolving a learning culture that includes TDD [test-driven development] and BDD [behavior-driven development] capturing of a story and automating the sequences of events that move from design, build, and test through implementation and production with continuous integration and delivery pipelines. A fail-first approach to testing, the ability to automate integration and delivery processes and include fast feedback throughout the lifecycle." + +Geoff highlights automated provisioning. "Picking one, automated provisioning has been hugely effective for my team. More specifically, automated provisioning from a versioned Infrastructure-as-Code codebase." + +Dan uses fun. "We do a lot of different things to create a DevOps culture. We hold 'lunch and learns' with free food to encourage everyone to come and learn together; we buy books and study in groups." + +### How do you motivate your team to achieve DevOps goals? + +``` +"Celebrate wins and visualize the progress made." +``` + +Daniel emphasizes "automation that matters. In order to minimize objection from multiple teams in a DevOps initiative, you should encourage your team to increase the automation capability of development, testing, and IT operations along with new processes and procedures. For example, a Linux container is the key tool to achieve the automation capability of DevOps." + +Geoff agrees, saying, "automate the toil. Are there tasks you hate doing? Great. Engineer them out of existence if possible. Otherwise, automate them. It keeps the job from becoming boring and routine because the job constantly evolves." + +Dan, Ann Marie, and Brent stress team motivation. + +Dan says, "at the NAIC, we have a great awards system for encouraging specific behaviors. We have multiple tiers of awards, and two of them can be given to anyone by anyone. We also give awards to teams after they complete something significant, but we often award individual contributors." + +According to Ann Marie, "the biggest motivator for teams in my area is seeing the success of others. We have a weekly playback for each other, and part of that is sharing what we've learned from trying out new tools or practices. When teams are enthusiastic about something they're doing and willing to help others get started, more teams will quickly get on board." + +Brent agrees. "Getting everyone educated and on the same baseline of knowledge is essential ... assessing what helps the team achieve [and] what it needs to deliver with the product owner and users is the first place I like to start." + +Chris recommends a two-pronged approach. "Run small, weekly goals that are achievable and agreed by the team as being important and [where] they can see progress outside of the feature work they are doing. Celebrate wins and visualize the progress made." + +### How do DevOps and agile work together? + +``` +"DevOps != Agile, second Agile != Scrum." +``` + +This is an important question because both DevOps and agile are cornerstones of modern software development. + +DevOps is a process of software development focusing on communication and collaboration to facilitate rapid application and product deployment, whereas agile is a development methodology involving continuous development, continuous iteration, and continuous testing to achieve predictable and quality deliverables. + +So, how do they relate? Let's ask the experts. + +In Brent's view, "DevOps != Agile, second Agile != Scrum. … Agile tools and ways of working—that support DevOps strategies and goals—are how they mesh together." + +Chris says, "agile is a fundamental component of DevOps for me. Sure, we could talk about how we adopt DevOps culture in a non-agile environment, but ultimately, improving agility in the way software is engineered is a key indicator as to the maturity of DevOps adoption within the organization." + +Dan relates DevOps to the larger [Agile Manifesto][8]. "I never talk about agile without referencing the Agile Manifesto in order to set the baseline. There are many implementations that don't focus on the Manifesto. When you read the Manifesto, they've really described DevOps from a development perspective. Therefore, it is very easy to fit agile into a DevOps culture, as agile is focused on communication, collaboration, flexibility to change, and getting to production quickly." + +Geoff sees "DevOps as one of many implementations of agile. Agile is essentially a set of principles, while DevOps is a culture, process, and toolchain that embodies those principles." + +Ann Marie keeps it succinct, saying "agile is a prerequisite for DevOps. DevOps makes agile more effective." + +### Has DevOps benefited from open source? + +``` +"Open source done well requires a DevOps culture." +``` + +This question receives a fervent "yes" from all participants followed by an explanation of the benefits they've seen. + +Ann Marie says, "we get to stand on the shoulders of giants and build upon what's already available. The open source model of maintaining software, with pull requests and code reviews, also works very well for DevOps teams." + +Chris agrees that DevOps has "undoubtedly" benefited from open source. "From the engineering and tooling side (e.g., Ansible), to the process and people side, through the sharing of stories within the industry and the open leadership community." + +A benefit Geoff cites is "grassroots adoption. Nobody had to sign purchase requisitions for free (as in beer) software. Teams found tooling that met their needs, were free (as in freedom) to modify, [then] built on top of it, and contributed enhancements back to the larger community. Rinse, repeat." + +Open source has shown DevOps "better ways you can adopt new changes and overcome challenges, just like open source software developers are doing it," says Daniel. + +Brent concurs. "DevOps has benefited in many ways from open source. One way is the ability to use the tools to understand how they can help accelerate DevOps goals and strategies. Educating the development and operations folks on crucial things like automation, virtualization and containerization, auto-scaling, and many of the qualities that are difficult to achieve without introducing technology enablers that make DevOps easier." + +Dan notes the two-way, symbiotic relationship between DevOps and open source. "Open source done well requires a DevOps culture. Most open source projects have very open communication structures with very little obscurity. This has actually been a great learning opportunity for DevOps practitioners around what they might bring into their own organizations. Also, being able to use tools from a community that is similar to that of your own organization only encourages your own culture growth. I like to use GitLab as an example of this symbiotic relationship. When I bring [GitLab] into a company, we get a great tool, but what I'm really buying is their unique culture. That brings substantial value through our interactions with them and our ability to contribute back. Their tool also has a lot to offer for a DevOps organization, but their culture has inspired awe in the companies where I've introduced it." + +Now that our DevOps experts have weighed in, please share your thoughts on what DevOps means—as well as the other questions we posed—in the comments. + + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/what-does-devops-mean-you + +作者：[Girish Managoli][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/gammay +[b]: https://github.com/lujun9972 +[1]: https://twitter.com/DukeAMO +[2]: https://twitter.com/danieloh30?lang=en +[3]: https://twitter.com/brentareed +[4]: https://twitter.com/barkerd427 +[5]: https://psnet.ahrq.gov/resources/resource/1582 +[6]: https://twitter.com/onlychrisbh?lang=en +[7]: https://twitter.com/geoff_purdy +[8]: https://agilemanifesto.org/ diff --git a/sources/tech/20190124 ffsend - Easily And Securely Share Files From Linux Command Line Using Firefox Send Client.md b/sources/tech/20190124 ffsend - Easily And Securely Share Files From Linux Command Line Using Firefox Send Client.md new file mode 100644 index 0000000000..fcbdd3c5c7 --- /dev/null +++ b/sources/tech/20190124 ffsend - Easily And Securely Share Files From Linux Command Line Using Firefox Send Client.md @@ -0,0 +1,330 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (ffsend – Easily And Securely Share Files From Linux Command Line Using Firefox Send Client) +[#]: via: (https://www.2daygeek.com/ffsend-securely-share-files-folders-from-linux-command-line-using-firefox-send-client/) +[#]: author: (Vinoth Kumar https://www.2daygeek.com/author/vinoth/) + +ffsend – Easily And Securely Share Files From Linux Command Line Using Firefox Send Client +====== + +Linux users were preferred to go with scp or rsync for files or folders copy. + +However, so many new options are coming to Linux because it’s a opensource. + +Anyone can develop a secure software for Linux. + +We had written multiple articles in our site in the past about this topic. + +Even, today we are going to discuss the same kind of topic called ffsend. + +Those are **[OnionShare][1]** , **[Magic Wormhole][2]** , **[Transfer.sh][3]** and **[Dcp – Dat Copy][4]**. + +### What’s ffsend? + +[ffsend][5] is a command line Firefox Send client that allow users to transfer and receive files and folders through command line. + +It allow us to easily and securely share files and directories from the command line through a safe, private and encrypted link using a single simple command. + +Files are shared using the Send service and the allowed file size is up to 2GB. + +Others are able to download these files with this tool, or through their web browser. + +All files are always encrypted on the client, and secrets are never shared with the remote host. + +Additionally you can add a password for the file upload. + +The uploaded files will be removed after the download (default count is 1 up to 10) or after 24 hours. This will make sure that your files does not remain online forever. + +This tool is currently in the alpha phase. Use at your own risk. Also, only limited installation options are available right now. + +### ffsend Features: + + * Fully featured and friendly command line tool + * Upload and download files and directories securely + * Always encrypted on the client + * Additional password protection, generation and configurable download limits + * Built-in file and directory archiving and extraction + * History tracking your files for easy management + * Ability to use your own Send host + * Inspect or delete shared files + * Accurate error reporting + * Low memory footprint, due to encryption and download/upload streaming + * Intended to be used in scripts without interaction + + + +### How To Install ffsend in Linux? + +There is no package for each distributions except Debian and Arch Linux systems. However, we can easily get this utility by downloading the prebuilt appropriate binaries file based on the operating system and architecture. + +Run the below command to download the latest available version for your operating system. + +``` +$ wget https://github.com/timvisee/ffsend/releases/download/v0.1.2/ffsend-v0.1.2-linux-x64.tar.gz +``` + +Extract the tar archive using the following command. + +``` +$ tar -xvf ffsend-v0.1.2-linux-x64.tar.gz +``` + +Run the following command to identify your path variable. + +``` +$ echo $PATH +/home/daygeek/.cargo/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl +``` + +As i told previously, just move the executable file to your path directory. + +``` +$ sudo mv ffsend /usr/local/sbin +``` + +Run the `ffsend` command alone to get the basic usage information. + +``` +$ ffsend +ffsend 0.1.2 +Usage: ffsend [FLAGS] ... + +Easily and securely share files from the command line. +A fully featured Firefox Send client. + +Missing subcommand. Here are the most used: + ffsend upload ... + ffsend download ... + +To show all subcommands, features and other help: + ffsend help [SUBCOMMAND] +``` + +For Arch Linux based users can easily install it with help of **[AUR Helper][6]** , as this package is available in AUR repository. + +``` +$ yay -S ffsend +``` + +For **`Debian/Ubuntu`** systems, use **[DPKG Command][7]** to install ffsend. + +``` +$ wget https://github.com/timvisee/ffsend/releases/download/v0.1.2/ffsend_0.1.2_amd64.deb +$ sudo dpkg -i ffsend_0.1.2_amd64.deb +``` + +### How To Send A File Using ffsend? + +It’s not complicated. We can easily send a file using simple syntax. + +**Syntax:** + +``` +$ ffsend upload [/Path/to/the/file/name] +``` + +In the following example, we are going to upload a file called `passwd-up1.sh`. Once you upload the file then you will be getting the unique URL. + +``` +$ ffsend upload passwd-up1.sh --copy +Upload complete +Share link: https://send.firefox.com/download/a4062553f4/#yy2_VyPaUMG5HwXZzYRmpQ +``` + +![][9] + +Just download the above unique URL to get the file in any remote system. + +**Syntax:** + +``` +$ ffsend download [Generated URL] +``` + +Output for the above command. + +``` +$ ffsend download https://send.firefox.com/download/a4062553f4/#yy2_VyPaUMG5HwXZzYRmpQ +Download complete +``` + +![][10] + +Use the following syntax format for directory upload. + +``` +$ ffsend upload [/Path/to/the/Directory] --copy +``` + +In this example, we are going to upload `2g` directory. + +``` +$ ffsend upload /home/daygeek/2g --copy +You've selected a directory, only a single file may be uploaded. +Archive the directory into a single file? [Y/n]: y +Archiving... +Upload complete +Share link: https://send.firefox.com/download/90aa5cfe67/#hrwu6oXZRG2DNh8vOc3BGg +``` + +Just download the above generated the unique URL to get a folder in any remote system. + +``` +$ ffsend download https://send.firefox.com/download/90aa5cfe67/#hrwu6oXZRG2DNh8vOc3BGg +You're downloading an archive, extract it into the selected directory? [Y/n]: y +Extracting... +Download complete +``` + +As this already send files through a safe, private, and encrypted link. However, if you would like to add a additional security at your level. Yes, you can add a password for a file. + +``` +$ ffsend upload file-copy-rsync.sh --copy --password +Password: +Upload complete +Share link: https://send.firefox.com/download/0742d24515/#P7gcNiwZJ87vF8cumU71zA +``` + +It will prompt you to update a password when you are trying to download a file in the remote system. + +``` +$ ffsend download https://send.firefox.com/download/0742d24515/#P7gcNiwZJ87vF8cumU71zA +This file is protected with a password. +Password: +Download complete +``` + +Alternatively you can limit a download speed by providing the download speed while uploading a file. + +``` +$ ffsend upload file-copy-scp.sh --copy --downloads 10 +Upload complete +Share link: https://send.firefox.com/download/23cb923c4e/#LVg6K0CIb7Y9KfJRNZDQGw +``` + +Just download the above unique URL to get a file in any remote system. + +``` +ffsend download https://send.firefox.com/download/23cb923c4e/#LVg6K0CIb7Y9KfJRNZDQGw +Download complete +``` + +If you want to see more details about the file, use the following format. It will shows you the file name, file size, Download counts and when it will going to expire. + +**Syntax:** + +``` +$ ffsend info [Generated URL] + +$ ffsend info https://send.firefox.com/download/23cb923c4e/#LVg6K0CIb7Y9KfJRNZDQGw +ID: 23cb923c4e +Name: file-copy-scp.sh +Size: 115 B +MIME: application/x-sh +Downloads: 3 of 10 +Expiry: 23h58m (86280s) +``` + +You can view your transaction history using the following format. + +``` +$ ffsend history +# LINK EXPIRY +1 https://send.firefox.com/download/23cb923c4e/#LVg6K0CIb7Y9KfJRNZDQGw 23h57m +2 https://send.firefox.com/download/0742d24515/#P7gcNiwZJ87vF8cumU71zA 23h55m +3 https://send.firefox.com/download/90aa5cfe67/#hrwu6oXZRG2DNh8vOc3BGg 23h52m +4 https://send.firefox.com/download/a4062553f4/#yy2_VyPaUMG5HwXZzYRmpQ 23h46m +5 https://send.firefox.com/download/74ff30e43e/#NYfDOUp_Ai-RKg5g0fCZXw 23h44m +6 https://send.firefox.com/download/69afaab1f9/#5z51_94jtxcUCJNNvf6RcA 23h43m +``` + +If you don’t want the link anymore then we can delete it. + +**Syntax:** + +``` +$ ffsend delete [Generated URL] + +$ ffsend delete https://send.firefox.com/download/69afaab1f9/#5z51_94jtxcUCJNNvf6RcA +File deleted +``` + +Alternatively this can be done using firefox browser by opening the page + +``` + +You can define multiple responses and, if you want, you could use an event or a service call inside the request to determine which response you may want to use. I opted for a response of type "view." A view is a rendered response; other types are request-redirects, forwards, and alike. The system comes with various renderers and allows you to determine the output later; to do so, add the following: + +``` + ++ + +``` + +Replace **my-component** with your own component name. Then you can define your very first screen by adding the following inside the tags within the **widget/CommonScreens.xml** file: + +``` + + +``` + +Screens are actually quite modular and consist of multiple elements ([widgets, actions, and decorators][15]). For the sake of simplicity, leave this as it is for now, and complete the new webpage by adding your very first templating toolkit file. For that, create a new **webapp/mycomponent/test/test.ftl** file and add the following: + +``` +<@alert type="info">Success! +``` + +![Custom screen][17] + +A custom screen. + +Open **+ ++ ++ ++ ++ ++DirectoryIndex index.html index.cgi index.pl index.php index.xhtml index.htm + + +# vim: syntax=apache ts=4 sw=4 sts=4 sr noet +``` + +Move the “index.php” file to first. Once you made the changes, your **dir.conf** file will look like below. + +``` ++DirectoryIndex index.php index.html index.cgi index.pl index.xhtml index.htm + + +# vim: syntax=apache ts=4 sw=4 sts=4 sr noet +``` + +Press **ESC** key and type **:wq** to save and close the file. Restart Apache service to take effect the changes. + +``` +$ sudo systemctl restart apache2 +``` + +##### 3.2 Install PHP modules + +To improve the functionality of PHP, you can install some additional PHP modules. + +To list the available PHP modules, run: + +``` +$ sudo apt-cache search php- | less +``` + +**Sample output:** + +![][4] + +Use the arrow keys to go through the result. To exit, type **q** and hit ENTER key. + +To find the details of any particular php module, for example **php-gd** , run: + +``` +$ sudo apt-cache show php-gd +``` + +To install a php module run: + +``` +$ sudo apt install php-gd +``` + +To install all modules (not necessary though), run: + +``` +$ sudo apt-get install php* +``` + +Do not forget to restart Apache service after installing any php module. To check if the module is loaded or not, open info.php file in your browser and check if it is present. + +Next, you might want to install any database management tools to easily manage databases via a web browser. If so, install phpMyAdmin as described in the following link. + +Congratulations! We have successfully setup LAMP stack in Ubuntu 18.04 LTS server. + + + +-------------------------------------------------------------------------------- + +via: https://www.ostechnix.com/install-apache-mysql-php-lamp-stack-on-ubuntu-18-04-lts/ + +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/2019/02/mysql-1.png +[3]: http://www.ostechnix.com/wp-content/uploads/2019/02/mysql-2.png +[4]: http://www.ostechnix.com/wp-content/uploads/2016/06/php-modules.png diff --git a/sources/tech/20190206 And, Ampersand, and - in Linux.md b/sources/tech/20190206 And, Ampersand, and - in Linux.md new file mode 100644 index 0000000000..2febc0a2ef --- /dev/null +++ b/sources/tech/20190206 And, Ampersand, and - in Linux.md @@ -0,0 +1,211 @@ +[#]: collector: (lujun9972) +[#]: translator: (HankChow) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (And, Ampersand, and & in Linux) +[#]: via: (https://www.linux.com/blog/learn/2019/2/and-ampersand-and-linux) +[#]: author: (Paul Brown https://www.linux.com/users/bro66) + +And, Ampersand, and & in Linux +====== + + +Take a look at the tools covered in the [three][1] [previous][2] [articles][3], and you will see that understanding the glue that joins them together is as important as recognizing the tools themselves. Indeed, tools tend to be simple, and understanding what _mkdir_ , _touch_ , and _find_ do (make a new directory, update a file, and find a file in the directory tree, respectively) in isolation is easy. + +But understanding what + +``` +mkdir test_dir 2>/dev/null || touch images.txt && find . -iname "*jpg" > backup/dir/images.txt & +``` + +does, and why we would write a command line like that is a whole different story. + +It pays to look more closely at the sign and symbols that live between the commands. It will not only help you better understand how things work, but will also make you more proficient in chaining commands together to create compound instructions that will help you work more efficiently. + +In this article and the next, we'll be looking at the the ampersand (`&`) and its close friend, the pipe (`|`), and see how they can mean different things in different contexts. + +### Behind the Scenes + +Let's start simple and see how you can use `&` as a way of pushing a command to the background. The instruction: + +``` +cp -R original/dir/ backup/dir/ +``` + +Copies all the files and subdirectories in _original/dir/_ into _backup/dir/_. So far so simple. But if that turns out to be a lot of data, it could tie up your terminal for hours. + +However, using: + +``` +cp -R original/dir/ backup/dir/ & +``` + +pushes the process to the background courtesy of the final `&`. This frees you to continue working on the same terminal or even to close the terminal and still let the process finish up. Do note, however, that if the process is asked to print stuff out to the standard output (like in the case of `echo` or `ls`), it will continue to do so, even though it is being executed in the background. + +When you push a process into the background, Bash will print out a number. This number is the PID or the _Process' ID_. Every process running on your Linux system has a unique process ID and you can use this ID to pause, resume, and terminate the process it refers to. This will become useful later. + +In the meantime, there are a few tools you can use to manage your processes as long as you remain in the terminal from which you launched them: + + * `jobs` shows you the processes running in your current terminal, whether be it in the background or foreground. It also shows you a number associated with each job (different from the PID) that you can use to refer to each process: + +``` + $ jobs +[1]- Running cp -i -R original/dir/* backup/dir/ & +[2]+ Running find . -iname "*jpg" > backup/dir/images.txt & +``` + + * `fg` brings a job from the background to the foreground so you can interact with it. You tell `fg` which process you want to bring to the foreground with a percentage symbol (`%`) followed by the number associated with the job that `jobs` gave you: + +``` + $ fg %1 # brings the cp job to the foreground +cp -i -R original/dir/* backup/dir/ +``` + +If the job was stopped (see below), `fg` will start it again. + + * You can stop a job in the foreground by holding down [Ctrl] and pressing [Z]. This doesn't abort the action, it pauses it. When you start it again with (`fg` or `bg`) it will continue from where it left off... + +...Except for [`sleep`][4]: the time a `sleep` job is paused still counts once `sleep` is resumed. This is because `sleep` takes note of the clock time when it was started, not how long it was running. This means that if you run `sleep 30` and pause it for more than 30 seconds, once you resume, `sleep` will exit immediately. + + * The `bg` command pushes a job to the background and resumes it again if it was paused: + +``` + $ bg %1 +[1]+ cp -i -R original/dir/* backup/dir/ & +``` + + + + +As mentioned above, you won't be able to use any of these commands if you close the terminal from which you launched the process or if you change to another terminal, even though the process will still continue working. + +To manage background processes from another terminal you need another set of tools. For example, you can tell a process to stop from a a different terminal with the [`kill`][5] command: + +``` +kill -s STOP+``` + +And you know the PID because that is the number Bash gave you when you started the process with `&`, remember? Oh! You didn't write it down? No problem. You can get the PID of any running process with the `ps` (short for _processes_ ) command. So, using + +``` +ps | grep cp +``` + +will show you all the processes containing the string " _cp_ ", including the copying job we are using for our example. It will also show you the PID: + +``` +$ ps | grep cp +14444 pts/3 00:00:13 cp +``` + +In this case, the PID is _14444_. and it means you can stop the background copying with: + +``` +kill -s STOP 14444 +``` + +Note that `STOP` here does the same thing as [Ctrl] + [Z] above, that is, it pauses the execution of the process. + +To start the paused process again, you can use the `CONT` signal: + +``` +kill -s CONT 14444 +``` + +There is a good list of many of [the main signals you can send a process here][6]. According to that, if you wanted to terminate the process, not just pause it, you could do this: + +``` +kill -s TERM 14444 +``` + +If the process refuses to exit, you can force it with: + +``` +kill -s KILL 14444 +``` + +This is a bit dangerous, but very useful if a process has gone crazy and is eating up all your resources. + +In any case, if you are not sure you have the correct PID, add the `x` option to `ps`: + +``` +$ ps x| grep cp +14444 pts/3 D 0:14 cp -i -R original/dir/Hols_2014.mp4 + original/dir/Hols_2015.mp4 original/dir/Hols_2016.mp4 + original/dir/Hols_2017.mp4 original/dir/Hols_2018.mp4 backup/dir/ +``` + +And you should be able to see what process you need. + +Finally, there is nifty tool that combines `ps` and `grep` all into one: + +``` +$ pgrep cp +8 +18 +19 +26 +33 +40 +47 +54 +61 +72 +88 +96 +136 +339 +6680 +13735 +14444 +``` + +Lists all the PIDs of processes that contain the string " _cp_ ". + +In this case, it isn't very helpful, but this... + +``` +$ pgrep -lx cp +14444 cp +``` + +... is much better. + +In this case, `-l` tells `pgrep` to show you the name of the process and `-x` tells `pgrep` you want an exact match for the name of the command. If you want even more details, try `pgrep -ax command`. + +### Next time + +Putting an `&` at the end of commands has helped us explain the rather useful concept of processes working in the background and foreground and how to manage them. + +One last thing before we leave: processes running in the background are what are known as _daemons_ in UNIX/Linux parlance. So, if you had heard the term before and wondered what they were, there you go. + +As usual, there are more ways to use the ampersand within a command line, many of which have nothing to do with pushing processes into the background. To see what those uses are, we'll be back next week with more on the matter. + +Read more: + +[Linux Tools: The Meaning of Dot][1] + +[Understanding Angle Brackets in Bash][2] + +[More About Angle Brackets in Bash][3] + +-------------------------------------------------------------------------------- + +via: https://www.linux.com/blog/learn/2019/2/and-ampersand-and-linux + +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/linux-tools-meaning-dot +[2]: https://www.linux.com/blog/learn/2019/1/understanding-angle-brackets-bash +[3]: https://www.linux.com/blog/learn/2019/1/more-about-angle-brackets-bash +[4]: https://ss64.com/bash/sleep.html +[5]: https://bash.cyberciti.biz/guide/Sending_signal_to_Processes +[6]: https://www.computerhope.com/unix/signals.htm diff --git a/sources/tech/20190206 Getting started with Vim visual mode.md b/sources/tech/20190206 Getting started with Vim visual mode.md new file mode 100644 index 0000000000..e6b9b1da9b --- /dev/null +++ b/sources/tech/20190206 Getting started with Vim visual mode.md @@ -0,0 +1,126 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Getting started with Vim visual mode) +[#]: via: (https://opensource.com/article/19/2/getting-started-vim-visual-mode) +[#]: author: (Susan Lauber https://opensource.com/users/susanlauber) + +Getting started with Vim visual mode +====== +Visual mode makes it easier to highlight and manipulate text in Vim. + + +Ansible playbook files are text files in a YAML format. People who work regularly with them have their favorite editors and plugin extensions to make the formatting easier. + +When I teach Ansible with the default editor available in most Linux distributions, I use Vim's visual mode a lot. It allows me to highlight my actions on the screen—what I am about to edit and the text manipulation task I'm doing—to make it easier for my students to learn. + +### Vim's visual mode + +When editing text with Vim, visual mode can be extremely useful for identifying chunks of text to be manipulated. + +Vim's visual mode has three versions: character, line, and block. The keystrokes to enter each mode are: + + * Character mode: **v** (lower-case) + * Line mode: **V** (upper-case) + * Block mode: **Ctrl+v** + + + +Here are some ways to use each mode to simplify your work. + +### Character mode + +Character mode can highlight a sentence in a paragraph or a phrase in a sentence. Then the visually identified text can be deleted, copied, changed, or modified with any other Vim editing command. + +#### Move a sentence + +To move a sentence from one place to another, start by opening the file and moving the cursor to the first character in the sentence you want to move. + + + + * Press the **v** key to enter visual character mode. The word **VISUAL** will appear at the bottom of the screen. + * Use the Arrow keys to highlight the desired text. You can use other navigation commands, such as **w** to highlight to the beginning of the next word or **$** to include the rest of the line. + * Once the text is highlighted, press the **d** key to delete the text. + * If you deleted too much or not enough, press **u** to undo and start again. + * Move your cursor to the new location and press **p** to paste the text. + + + +#### Change a phrase + +You can also highlight a chunk of text that you want to replace. + + + + * Place the cursor at the first character you want to change. + * Press **v** to enter visual character mode. + * Use navigation commands, such as the Arrow keys, to highlight the phrase. + * Press **c** to change the highlighted text. + * The highlighted text will disappear, and you will be in Insert mode where you can add new text. + * After you finish typing the new text, press **Esc** to return to command mode and save your work. + + + +### Line mode + +When working with Ansible playbooks, the order of tasks can matter. Use visual line mode to move a task to a different location in the playbook. + +#### Manipulate multiple lines of text + + + + * Place your cursor anywhere on the first or last line of the text you want to manipulate. + * Press **Shift+V** to enter line mode. The words **VISUAL LINE** will appear at the bottom of the screen. + * Use navigation commands, such as the Arrow keys, to highlight multiple lines of text. + * Once the desired text is highlighted, use commands to manipulate it. Press **d** to delete, then move the cursor to the new location, and press **p** to paste the text. + * **y** (yank) can be used instead of **d** (delete) if you want to copy the task. + + + +#### Indent a set of lines + +When working with Ansible playbooks or YAML files, indentation matters. A highlighted block can be shifted right or left with the **>** and **<** keys. + +![]9https://opensource.com/sites/default/files/uploads/vim-visual-line2.png + + * Press **>** to increase the indentation of all the lines. + * Press **<** to decrease the indentation of all the lines. + + + +Try other Vim commands to apply them to the highlighted text. + +### Block mode + +The visual block mode is useful for manipulation of specific tabular data files, but it can also be extremely helpful as a tool to verify indentation of an Ansible playbook. + +Tasks are a list of items and in YAML each list item starts with a dash followed by a space. The dashes must line up in the same column to be at the same indentation level. This can be difficult to see with just the human eye. Indentation of other lines within the task is also important. + +#### Verify tasks lists are indented the same + + + + * Place your cursor on the first character of the list item. + * Press **Ctrl+v** to enter visual block mode. The words **VISUAL BLOCK** will appear at the bottom of the screen. + * Use the Arrow keys to highlight the single character column. You can verify that each task is indented the same amount. + * Use the Arrow keys to expand the block right or left to check whether the other indentation is correct. + + + +Even though I am comfortable with other Vim editing shortcuts, I still like to use visual mode to sort out what text I want to manipulate. When I demo other concepts during a presentation, my students see a tool to highlight text and hit delete in this "new to them" text only editor. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/2/getting-started-vim-visual-mode + +作者：[Susan Lauber][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/susanlauber +[b]: https://github.com/lujun9972 diff --git a/sources/tech/20190208 3 Ways to Install Deb Files on Ubuntu Linux.md b/sources/tech/20190208 3 Ways to Install Deb Files on Ubuntu Linux.md new file mode 100644 index 0000000000..3b84d85c62 --- /dev/null +++ b/sources/tech/20190208 3 Ways to Install Deb Files on Ubuntu Linux.md @@ -0,0 +1,185 @@ +[#]: collector: (lujun9972) +[#]: translator: (sndnvaps) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (3 Ways to Install Deb Files on Ubuntu Linux) +[#]: via: (https://itsfoss.com/install-deb-files-ubuntu) +[#]: author: (Abhishek Prakash https://itsfoss.com/author/abhishek/) + +3 Ways to Install Deb Files on Ubuntu Linux +====== + +**This beginner article explains how to install deb packages in Ubuntu. It also shows you how to remove those deb packages afterwards.** + +This is another article in the Ubuntu beginner series. If you are absolutely new to Ubuntu, you might wonder about [how to install applications][1]. + +The easiest way is to use the Ubuntu Software Center. Search for an application by its name and install it from there. + +Life would be too simple if you could find all the applications in the Software Center. But that does not happen, unfortunately. + +Some software are available via DEB packages. These are archived files that end with .deb extension. + +You can think of .deb files as the .exe files in Windows. You double click on the .exe file and it starts the installation procedure in Windows. DEB packages are pretty much the same. + +You can find these DEB packages from the download section of the software provider’s website. For example, if you want to [install Google Chrome on Ubuntu][2], you can download the DEB package of Chrome from its website. + +Now the question arises, how do you install deb files? There are multiple ways of installing DEB packages in Ubuntu. I’ll show them to you one by one in this tutorial. + +![Install deb files in Ubuntu][3] + +### Installing .deb files in Ubuntu and Debian-based Linux Distributions + +You can choose a GUI tool or a command line tool for installing a deb package. The choice is yours. + +Let’s go on and see how to install deb files. + +#### Method 1: Use the default Software Center + +The simplest method is to use the default software center in Ubuntu. You have to do nothing special here. Simply go to the folder where you have downloaded the .deb file (it should be the Downloads folder) and double click on this file. + +![Google Chrome deb file on Ubuntu][4]Double click on the downloaded .deb file to start installation + +It will open the software center and you should see the option to install the software. All you have to do is to hit the install button and enter your login password. + +![Install Google Chrome in Ubuntu Software Center][5]The installation of deb file will be carried out via Software Center + +See, it’s even simple than installing from a .exe files on Windows, isn’t it? + +#### Method 2: Use Gdebi application for installing deb packages with dependencies + +Again, life would be a lot simpler if things always go smooth. But that’s not life as we know it. + +Now that you know that .deb files can be easily installed via Software Center, let me tell you about the dependency error that you may encounter with some packages. + +What happens is that a program may be dependent on another piece of software (libraries). When the developer is preparing the DEB package for you, he/she may assume that your system already has that piece of software on your system. + +But if that’s not the case and your system doesn’t have those required pieces of software, you’ll encounter the infamous ‘dependency error’. + +The Software Center cannot handle such errors on its own so you have to use another tool called [gdebi][6]. + +gdebi is a lightweight GUI application that has the sole purpose of installing deb packages. + +It identifies the dependencies and tries to install these dependencies along with installing the .deb files. + +![gdebi handling dependency while installing deb package][7]Image Credit: [Xmodulo][8] + +Personally, I prefer gdebi over software center for installing deb files. It is a lightweight application so the installation seems quicker. You can read in detail about [using gDebi and making it the default for installing DEB packages][6]. + +You can install gdebi from the software center or using the command below: + +``` +sudo apt install gdebi +``` + +#### Method 3: Install .deb files in command line using dpkg + +If you want to install deb packages in command lime, you can use either apt command or dpkg command. Apt command actually uses [dpkg command][9] underneath it but apt is more popular and easy to use. + +If you want to use the apt command for deb files, use it like this: + +``` +sudo apt install path_to_deb_file +``` + +If you want to use dpkg command for installing deb packages, here’s how to do it: + +``` +sudo dpkg -i path_to_deb_file +``` + +In both commands, you should replace the path_to_deb_file with the path and name of the deb file you have downloaded. + +![Install deb files using dpkg command in Ubuntu][10]Installing deb files using dpkg command in Ubuntu + +If you get a dependency error while installing the deb packages, you may use the following command to fix the dependency issues: + +``` +sudo apt install -f +``` + +### How to remove deb packages + +Removing a deb package is not a big deal as well. And no, you don’t need the original deb file that you had used for installing the program. + +#### Method 1: Remove deb packages using apt commands + +All you need is the name of the program that you have installed and then you can use apt or dpkg to remove that program. + +``` +sudo apt remove program_name +``` + +Now the question comes, how do you find the exact program name that you need to use in the remove command? The apt command has a solution for that as well. + +You can find the list of all installed files with apt command but manually going through this will be a pain. So you can use the grep command to search for your package. + +For example, I installed AppGrid application in the previous section but if I want to know the exact program name, I can use something like this: + +``` +sudo apt list --installed | grep grid +``` + +This will give me all the packages that have grid in their name and from there, I can get the exact program name. + +``` +apt list --installed | grep grid +WARNING: apt does not have a stable CLI interface. Use with caution in scripts. +appgrid/now 0.298 all [installed,local] +``` + +As you can see, a program called appgrid has been installed. Now you can use this program name with the apt remove command. + +#### Method 2: Remove deb packages using dpkg commands + +You can use dpkg to find the installed program’s name: + +``` +dpkg -l | grep grid +``` + +The output will give all the packages installed that has grid in its name. + +``` +dpkg -l | grep grid + +ii appgrid 0.298 all Discover and install apps for Ubuntu +``` + +ii in the above command output means package has been correctly installed. + +Now that you have the program name, you can use dpkg command to remove it: + +``` +dpkg -r program_name +``` + +**Tip: Updating deb packages** +Some deb packages (like Chrome) provide updates through system updates but for most other programs, you’ll have to remove the existing program and install the newer version. + +I hope this beginner guide helped you to install deb packages on Ubuntu. I added the remove part so that you’ll have better control over the programs you installed. + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/install-deb-files-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://itsfoss.com/remove-install-software-ubuntu/ +[2]: https://itsfoss.com/install-chrome-ubuntu/ +[3]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/02/deb-packages-ubuntu.png?resize=800%2C450&ssl=1 +[4]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/01/install-google-chrome-ubuntu-4.jpeg?resize=800%2C347&ssl=1 +[5]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/install-google-chrome-ubuntu-5.jpeg?resize=800%2C516&ssl=1 +[6]: https://itsfoss.com/gdebi-default-ubuntu-software-center/ +[7]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/01/gdebi-handling-dependency.jpg?ssl=1 +[8]: http://xmodulo.com +[9]: https://help.ubuntu.com/lts/serverguide/dpkg.html.en +[10]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/02/install-deb-file-with-dpkg.png?ssl=1 +[11]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/02/deb-packages-ubuntu.png?fit=800%2C450&ssl=1 diff --git a/sources/tech/20190208 7 steps for hunting down Python code bugs.md b/sources/tech/20190208 7 steps for hunting down Python code bugs.md new file mode 100644 index 0000000000..77b2c802a0 --- /dev/null +++ b/sources/tech/20190208 7 steps for hunting down Python code bugs.md @@ -0,0 +1,114 @@ +[#]: collector: (lujun9972) +[#]: translator: (LazyWolfLin) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (7 steps for hunting down Python code bugs) +[#]: via: (https://opensource.com/article/19/2/steps-hunting-code-python-bugs) +[#]: author: (Maria Mckinley https://opensource.com/users/parody) + +7 steps for hunting down Python code bugs +====== +Learn some tricks to minimize the time you spend tracking down the reasons your code fails. + + +It is 3 pm on a Friday afternoon. Why? Because it is always 3 pm on a Friday when things go down. You get a notification that a customer has found a bug in your software. After you get over your initial disbelief, you contact DevOps to find out what is happening with the logs for your app, because you remember receiving a notification that they were being moved. + +Turns out they are somewhere you can't get to, but they are in the process of being moved to a web application—so you will have this nifty application for searching and reading them, but of course, it is not finished yet. It should be up in a couple of days. I know, totally unrealistic situation, right? Unfortunately not; it seems logs or log messages often come up missing at just the wrong time. Before we track down the bug, a public service announcement: Check your logs to make sure they are where you think they are and logging what you think they should log, regularly. Amazing how these things just change when you aren't looking. + +OK, so you found the logs or tried the call, and indeed, the customer has found a bug. Maybe you even think you know where the bug is. + +You immediately open the file you think might be the problem and start poking around. + +### 1. Don't touch your code yet + +Go ahead and look at it, maybe even come up with a hypothesis. But before you start mucking about in the code, take that call that creates the bug and turn it into a test. This will be an integration test because although you may have suspicions, you do not yet know exactly where the problem is. + +Make sure this test fails. This is important because sometimes the test you make doesn't mimic the broken call; this is especially true if you are using a web or other framework that can obfuscate the tests. Many things may be stored in variables, and it is unfortunately not always obvious, just by looking at the test, what call you are making in the test. I'm not going to say that I have created a test that passed when I was trying to imitate a broken call, but, well, I have, and I don't think that is particularly unusual. Learn from my mistakes. + +### 2. Write a failing test + +Now that you have a failing test or maybe a test with an error, it is time to troubleshoot. But before you do that, let's do a review of the stack, as this makes troubleshooting easier. + +The stack consists of all of the tasks you have started but not finished. So, if you are baking a cake and adding the flour to the batter, then your stack would be: + + * Make cake + * Make batter + * Add flour + + + +You have started making your cake, you have started making the batter, and you are adding the flour. Greasing the pan is not on the list since you already finished that, and making the frosting is not on the list because you have not started that. + +If you are fuzzy on the stack, I highly recommend playing around on [Python Tutor][1], where you can watch the stack as you execute lines of code. + +Now, if something goes wrong with your Python program, the interpreter helpfully prints out the stack for you. This means that whatever the program was doing at the moment it became apparent that something went wrong is on the bottom. + +### 3. Always check the bottom of the stack first + +Not only is the bottom of the stack where you can see which error occurred, but often the last line of the stack is where you can find the issue. If the bottom doesn't help, and your code has not been linted in a while, it is amazing how helpful it can be to run. I recommend pylint or flake8. More often than not, it points right to where there is an error that I have been overlooking. + +If the error is something that seems obscure, your next move might just be to Google it. You will have better luck if you don't include information that is relevant only to your code, like the name of variables, files, etc. If you are using Python 3 (which you should be), it's helpful to include the 3 in the search; otherwise, Python 2 solutions tend to dominate the top. + +Once upon a time, developers had to troubleshoot without the benefit of a search engine. This was a dark time. Take advantage of all the tools available to you. + +Unfortunately, sometimes the problem occurred earlier and only became apparent during the line executed on the bottom of the stack. Think about how forgetting to add the baking powder becomes obvious when the cake doesn't rise. + +It is time to look up the stack. Chances are quite good that the problem is in your code, and not Python core or even third-party packages, so scan the stack looking for lines in your code first. Plus it is usually much easier to put a breakpoint in your own code. Stick the breakpoint in your code a little further up the stack and look around to see if things look like they should. + +"But Maria," I hear you say, "this is all helpful if I have a stack trace, but I just have a failing test. Where do I start?" + +Pdb, the Python Debugger. + +Find a place in your code where you know this call should hit. You should be able to find at least one place. Stick a pdb break in there. + +#### A digression + +Why not a print statement? I used to depend on print statements. They still come in handy sometimes. But once I started working with complicated code bases, and especially ones making network calls, print just became too slow. I ended up with print statements all over the place, I lost track of where they were and why, and it just got complicated. But there is a more important reason to mostly use pdb. Let's say you put a print statement in and discover that something is wrong—and must have gone wrong earlier. But looking at the function where you put the print statement, you have no idea how you got there. Looking at code is a great way to see where you are going, but it is terrible for learning where you've been. And yes, I have done a grep of my code base looking for where a function is called, but this can get tedious and doesn't narrow it down much with a popular function. Pdb can be very helpful. + +You follow my advice, and put in a pdb break and run your test. And it whooshes on by and fails again, with no break at all. Leave your breakpoint in, and run a test already in your test suite that does something very similar to the broken test. If you have a decent test suite, you should be able to find a test that is hitting the same code you think your failed test should hit. Run that test, and when it gets to your breakpoint, do a `w` and look at the stack. If you have no idea by looking at the stack how/where the other call may have gone haywire, then go about halfway up the stack, find some code that belongs to you, and put a breakpoint in that file, one line above the one in the stack trace. Try again with the new test. Keep going back and forth, moving up the stack to figure out where your call went off the rails. If you get all the way up to the top of the trace without hitting a breakpoint, then congratulations, you have found the issue: Your app was spelled wrong. No experience here, nope, none at all. + +### 4. Change things + +If you still feel lost, try making a new test where you vary something slightly. Can you get the new test to work? What is different? What is the same? Try changing something else. Once you have your test, and maybe additional tests in place, it is safe to start changing things in the code to see if you can narrow down the problem. Remember to start troubleshooting with a fresh commit so you can easily back out changes that do not help. (This is a reference to version control, if you aren't using version control, it will change your life. Well, maybe it will just make coding easier. See "[A Visual Guide to Version Control][2]" for a nice introduction.) + +### 5. Take a break + +In all seriousness, when it stops feeling like a fun challenge or game and starts becoming really frustrating, your best course of action is to walk away from the problem. Take a break. I highly recommend going for a walk and trying to think about something else. + +### 6. Write everything down + +When you come back, if you aren't suddenly inspired to try something, write down any information you have about the problem. This should include: + + * Exactly the call that is causing the problem + * Exactly what happened, including any error messages or related log messages + * Exactly what you were expecting to happen + * What you have done so far to find the problem and any clues that you have discovered while troubleshooting + + + +Sometimes this is a lot of information, but trust me, it is really annoying trying to pry information out of someone piecemeal. Try to be concise, but complete. + +### 7. Ask for help + +I often find that just writing down all the information triggers a thought about something I have not tried yet. Sometimes, of course, I realize what the problem is immediately after hitting the submit button. At any rate, if you still have not thought of anything after writing everything down, try sending an email to someone. First, try colleagues or other people involved in your project, then move on to project email lists. Don't be afraid to ask for help. Most people are kind and helpful, and I have found that to be especially true in the Python community. + +Maria McKinley will present [Hunting the Bugs][3] at [PyCascades 2019][4], February 23-24 in Seattle. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/2/steps-hunting-code-python-bugs + +作者：[Maria Mckinley][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/parody +[b]: https://github.com/lujun9972 +[1]: http://www.pythontutor.com/ +[2]: https://betterexplained.com/articles/a-visual-guide-to-version-control/ +[3]: https://2019.pycascades.com/talks/hunting-the-bugs +[4]: https://2019.pycascades.com/ diff --git a/sources/tech/20190211 How To Remove-Delete The Empty Lines In A File In Linux.md b/sources/tech/20190211 How To Remove-Delete The Empty Lines In A File In Linux.md new file mode 100644 index 0000000000..b55cbcd811 --- /dev/null +++ b/sources/tech/20190211 How To Remove-Delete The Empty Lines In A File In Linux.md @@ -0,0 +1,192 @@ +[#]: collector: (lujun9972) +[#]: translator: ( pityonline ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How To Remove/Delete The Empty Lines In A File In Linux) +[#]: via: (https://www.2daygeek.com/remove-delete-empty-lines-in-a-file-in-linux/) +[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/) + +How To Remove/Delete The Empty Lines In A File In Linux +====== + +Some times you may wants to remove or delete the empty lines in a file in Linux. + +If so, you can use the one of the below method to achieve it. + +It can be done in many ways but i have listed simple methods in the article. + +You may aware of that grep, awk and sed commands are specialized for textual data manipulation. + +Navigate to the following URL, if you would like to read more about these kind of topics. For **[creating a file in specific size in Linux][1]** multiple ways, for **[creating a file in Linux][2]** multiple ways and for **[removing a matching string from a file in Linux][3]**. + +These are fall in advanced commands category because these are used in most of the shell script to do required things. + +It can be done using the following 5 methods. + + * **`sed Command:`** Stream editor for filtering and transforming text. + * **`grep Command:`** Print lines that match patterns. + * **`cat Command:`** It concatenate files and print on the standard output. + * **`tr Command:`** Translate or delete characters. + * **`awk Command:`** The awk utility shall execute programs written in the awk programming language, which is specialized for textual data manipulation. + * **`perl Command:`** Perl is a programming language specially designed for text editing. + + + +To test this, i had already created the file called `2daygeek.txt` with some texts and empty lines. The details are below. + +``` +$ cat 2daygeek.txt +2daygeek.com is a best Linux blog to learn Linux. + +It's FIVE years old blog. + +This website is maintained by Magesh M, it's licensed under CC BY-NC 4.0. + +He got two GIRL babys. + +Her names are Tanisha & Renusha. +``` + +Now everything is ready and i’m going to test this in multiple ways. + +### How To Remove/Delete The Empty Lines In A File In Linux Using sed Command? + +Sed is a stream editor. A stream editor is used to perform basic text transformations on an input stream (a file or input from a pipeline). + +``` +$ sed '/^$/d' 2daygeek.txt +2daygeek.com is a best Linux blog to learn Linux. +It's FIVE years old blog. +This website is maintained by Magesh M, it's licensed under CC BY-NC 4.0. +He got two GIRL babes. +Her names are Tanisha & Renusha. +``` + +Details are follow: + + * **`sed:`** It’s a command + * **`//:`** It holds the searching string. + * **`^:`** Matches start of string. + * **`$:`** Matches end of string. + * **`d:`** Delete the matched string. + * **`2daygeek.txt:`** Source file name. + + + +### How To Remove/Delete The Empty Lines In A File In Linux Using grep Command? + +grep searches for PATTERNS in each FILE. PATTERNS is one or patterns separated by newline characters, and grep prints each line that matches a pattern. + +``` +$ grep . 2daygeek.txt +or +$ grep -Ev "^$" 2daygeek.txt +or +$ grep -v -e '^$' 2daygeek.txt +2daygeek.com is a best Linux blog to learn Linux. +It's FIVE years old blog. +This website is maintained by Magesh M, it's licensed under CC BY-NC 4.0. +He got two GIRL babes. +Her names are Tanisha & Renusha. +``` + +Details are follow: + + * **`grep:`** It’s a command + * **`.:`** Replaces any character. + * **`^:`** matches start of string. + * **`$:`** matches end of string. + * **`E:`** For extended regular expressions pattern matching. + * **`e:`** For regular expressions pattern matching. + * **`v:`** To select non-matching lines from the file. + * **`2daygeek.txt:`** Source file name. + + + +### How To Remove/Delete The Empty Lines In A File In Linux Using awk Command? + +The awk utility shall execute programs written in the awk programming language, which is specialized for textual data manipulation. An awk program is a sequence of patterns and corresponding actions. + +``` +$ awk NF 2daygeek.txt +or +$ awk '!/^$/' 2daygeek.txt +or +$ awk '/./' 2daygeek.txt +2daygeek.com is a best Linux blog to learn Linux. +It's FIVE years old blog. +This website is maintained by Magesh M, it's licensed under CC BY-NC 4.0. +He got two GIRL babes. +Her names are Tanisha & Renusha. +``` + +Details are follow: + + * **`awk:`** It’s a command + * **`//:`** It holds the searching string. + * **`^:`** matches start of string. + * **`$:`** matches end of string. + * **`.:`** Replaces any character. + * **`!:`** Delete the matched string. + * **`2daygeek.txt:`** Source file name. + + + +### How To Delete The Empty Lines In A File In Linux using Combination of cat And tr Command? + +cat stands for concatenate. It is very frequently used in Linux to reads data from a file. + +cat is one of the most frequently used commands on Unix-like operating systems. It’s offer three functions which is related to text file such as display content of a file, combine multiple files into the single output and create a new file. + +Translate, squeeze, and/or delete characters from standard input, writing to standard output. + +``` +$ cat 2daygeek.txt | tr -s '\n' +2daygeek.com is a best Linux blog to learn Linux. +It's FIVE years old blog. +This website is maintained by Magesh M, it's licensed under CC BY-NC 4.0. +He got two GIRL babes. +Her names are Tanisha & Renusha. +``` + +Details are follow: + + * **`cat:`** It’s a command + * **`tr:`** It’s a command + * **`|:`** Pipe symbol. It pass first command output as a input to another command. + * **`s:`** Replace each sequence of a repeated character that is listed in the last specified SET. + * **`\n:`** To add a new line. + * **`2daygeek.txt:`** Source file name. + + + +### How To Remove/Delete The Empty Lines In A File In Linux Using perl Command? + +Perl stands in for “Practical Extraction and Reporting Language”. Perl is a programming language specially designed for text editing. It is now widely used for a variety of purposes including Linux system administration, network programming, web development, etc. + +``` +$ perl -ne 'print if /\S/' 2daygeek.txt +2daygeek.com is a best Linux blog to learn Linux. +It's FIVE years old blog. +This website is maintained by Magesh M, it's licensed under CC BY-NC 4.0. +He got two GIRL babes. +Her names are Tanisha & Renusha. +``` + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/remove-delete-empty-lines-in-a-file-in-linux/ + +作者：[Magesh Maruthamuthu][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://www.2daygeek.com/author/magesh/ +[b]: https://github.com/lujun9972 +[1]: https://www.2daygeek.com/create-a-file-in-specific-certain-size-linux/ +[2]: https://www.2daygeek.com/linux-command-to-create-a-file/ +[3]: https://www.2daygeek.com/empty-a-file-delete-contents-lines-from-a-file-remove-matching-string-from-a-file-remove-empty-blank-lines-from-a-file/ diff --git a/sources/tech/20190211 How does rootless Podman work.md b/sources/tech/20190211 How does rootless Podman work.md new file mode 100644 index 0000000000..a085ae9014 --- /dev/null +++ b/sources/tech/20190211 How does rootless Podman work.md @@ -0,0 +1,107 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How does rootless Podman work?) +[#]: via: (https://opensource.com/article/19/2/how-does-rootless-podman-work) +[#]: author: (Daniel J Walsh https://opensource.com/users/rhatdan) + +How does rootless Podman work? +====== +Learn how Podman takes advantage of user namespaces to run in rootless mode. + + +In my [previous article][1] on user namespace and [Podman][2], I discussed how you can use Podman commands to launch different containers with different user namespaces giving you better separation between containers. Podman also takes advantage of user namespaces to be able to run in rootless mode. Basically, when a non-privileged user runs Podman, the tool sets up and joins a user namespace. After Podman becomes root inside of the user namespace, Podman is allowed to mount certain filesystems and set up the container. Note there is no privilege escalation here other then additional UIDs available to the user, explained below. + +### How does Podman create the user namespace? + +#### shadow-utils + +Most current Linux distributions include a version of shadow-utils that uses the **/etc/subuid** and **/etc/subgid** files to determine what UIDs and GIDs are available for a user in a user namespace. + +``` +$ cat /etc/subuid +dwalsh:100000:65536 +test:165536:65536 +$ cat /etc/subgid +dwalsh:100000:65536 +test:165536:65536 +``` + +The useradd program automatically allocates 65536 UIDs for each user added to the system. If you have existing users on a system, you would need to allocate the UIDs yourself. The format of these files is **username:STARTUID:TOTALUIDS**. Meaning in my case, dwalsh is allocated UIDs 100000 through 165535 along with my default UID, which happens to be 3265 defined in /etc/passwd. You need to be careful when allocating these UID ranges that they don't overlap with any **real** UID on the system. If you had a user listed as UID 100001, now I (dwalsh) would be able to become this UID and potentially read/write/execute files owned by the UID. + +Shadow-utils also adds two setuid programs (or setfilecap). On Fedora I have: + +``` +$ getcap /usr/bin/newuidmap +/usr/bin/newuidmap = cap_setuid+ep +$ getcap /usr/bin/newgidmap +/usr/bin/newgidmap = cap_setgid+ep +``` + +Podman executes these files to set up the user namespace. You can see the mappings by examining /proc/self/uid_map and /proc/self/gid_map from inside of the rootless container. + +``` +$ podman run alpine cat /proc/self/uid_map /proc/self/gid_map + 0 3267 1 + 1 100000 65536 + 0 3267 1 + 1 100000 65536 +``` + +As seen above, Podman defaults to mapping root in the container to your current UID (3267) and then maps ranges of allocated UIDs/GIDs in /etc/subuid and /etc/subgid starting at 1. Meaning in my example, UID=1 in the container is UID 100000, UID=2 is UID 100001, all the way up to 65536, which is 165535. + +Any item from outside of the user namespace that is owned by a UID or GID that is not mapped into the user namespace appears to belong to the user configured in the **kernel.overflowuid** sysctl, which by default is 35534, which my /etc/passwd file says has the name **nobody**. Since your process can't run as an ID that isn't mapped, the owner and group permissions don't apply, so you can only access these files based on their "other" permissions. This includes all files owned by **real** root on the system running the container, since root is not mapped into the user namespace. + +The [Buildah][3] command has a cool feature, [**buildah unshare**][4]. This puts you in the same user namespace that Podman runs in, but without entering the container's filesystem, so you can list the contents of your home directory. + +``` +$ ls -ild /home/dwalsh +8193 drwx--x--x. 290 dwalsh dwalsh 20480 Jan 29 07:58 /home/dwalsh +$ buildah unshare ls -ld /home/dwalsh +drwx--x--x. 290 root root 20480 Jan 29 07:58 /home/dwalsh +``` + +Notice that when listing the home dir attributes outside the user namespace, the kernel reports the ownership as dwalsh, while inside the user namespace it reports the directory as owned by root. This is because the home directory is owned by 3267, and inside the user namespace we are treating that UID as root. + +### What happens next in Podman after the user namespace is set up? + +Podman uses [containers/storage][5] to pull the container image, and containers/storage is smart enough to map all files owned by root in the image to the root of the user namespace, and any other files owned by different UIDs to their user namespace UIDs. By default, this content gets written to ~/.local/share/containers/storage. Container storage works in rootless mode with either the vfs mode or with Overlay. Note: Overlay is supported only if the [fuse-overlayfs][6] executable is installed. + +The kernel only allows user namespace root to mount certain types of filesystems; at this time it allows mounting of procfs, sysfs, tmpfs, fusefs, and bind mounts (as long as the source and destination are owned by the user running Podman. OverlayFS is not supported yet, although the kernel teams are working on allowing it). + +Podman then mounts the container's storage if it is using fuse-overlayfs; if the storage driver is using vfs, then no mounting is required. Podman on vfs requires a lot of space though, since each container copies the entire underlying filesystem. + +Podman then mounts /proc and /sys along with a few tmpfs and creates the devices in the container. + +In order to use networking other than the host networking, Podman uses the [slirp4netns][7] program to set up **User mode networking for unprivileged network namespace**. Slirp4netns allows Podman to expose ports within the container to the host. Note that the kernel still will not allow a non-privileged process to bind to ports less than 1024. Podman-1.1 or later is required for binding to ports. + +Rootless Podman can use user namespace for container separation, but you only have access to the UIDs defined in the /etc/subuid file. + +### Conclusion + +The Podman tool is enabling people to build and use containers without sacrificing the security of the system; you can give your developers the access they need without giving them root. + +And when you put your containers into production, you can take advantage of the extra security provided by the user namespace to keep the workloads isolated from each other. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/2/how-does-rootless-podman-work + +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://opensource.com/article/18/12/podman-and-user-namespaces +[2]: https://podman.io/ +[3]: https://buildah.io/ +[4]: https://github.com/containers/buildah/blob/master/docs/buildah-unshare.md +[5]: https://github.com/containers/storage +[6]: https://github.com/containers/fuse-overlayfs +[7]: https://github.com/rootless-containers/slirp4netns diff --git a/sources/tech/20190211 What-s the right amount of swap space for a modern Linux system.md b/sources/tech/20190211 What-s the right amount of swap space for a modern Linux system.md new file mode 100644 index 0000000000..c04d47e5ca --- /dev/null +++ b/sources/tech/20190211 What-s the right amount of swap space for a modern Linux system.md @@ -0,0 +1,68 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (What's the right amount of swap space for a modern Linux system?) +[#]: via: (https://opensource.com/article/19/2/swap-space-poll) +[#]: author: (David Both https://opensource.com/users/dboth) + +What's the right amount of swap space for a modern Linux system? +====== +Complete our survey and voice your opinion on how much swap space to allocate. + + +Swap space is one of those things that everyone seems to have an idea about, and I am no exception. All my sysadmin friends have their opinions, and most distributions make recommendations too. + +Many years ago, the rule of thumb for the amount of swap space that should be allocated was 2X the amount of RAM installed in the computer. Of course that was when a typical computer's RAM was measured in KB or MB. So if a computer had 64KB of RAM, a swap partition of 128KB would be an optimum size. + +This took into account the fact that RAM memory sizes were typically quite small, and allocating more than 2X RAM for swap space did not improve performance. With more than twice RAM for swap, most systems spent more time thrashing than performing useful work. + +RAM memory has become quite inexpensive and many computers now have RAM in the tens of gigabytes. Most of my newer computers have at least 4GB or 8GB of RAM, two have 32GB, and my main workstation has 64GB. When dealing with computers with huge amounts of RAM, the limiting performance factor for swap space is far lower than the 2X multiplier. As a consequence, recommended swap space is considered a function of system memory workload, not system memory. + +Table 1 provides the Fedora Project's recommended size for a swap partition, depending on the amount of RAM in your system and whether you want enough memory for your system to hibernate. To allow for hibernation, you need to edit the swap space in the custom partitioning stage. The "recommended" swap partition size is established automatically during a default installation, but I usually find it's either too large or too small for my needs. + +The [Fedora 28 Installation Guide][1] defines current thinking about swap space allocation. Note that other versions of Fedora and other Linux distributions may differ slightly, but this is the same table Red Hat Enterprise Linux uses for its recommendations. These recommendations have not changed since Fedora 19. + +| Amount of RAM installed in system | Recommended swap space | Recommended swap space with hibernation | +| --------------------------------- | ---------------------- | --------------------------------------- | +| ≤ 2GB | 2X RAM | 3X RAM | +| 2GB – 8GB | = RAM | 2X RAM | +| 8GB – 64GB | 4G to 0.5X RAM | 1.5X RAM | +| >64GB | Minimum 4GB | Hibernation not recommended | + +Table 1: Recommended system swap space in Fedora 28's documentation. + +Table 2 contains my recommendations based on my experiences in multiple environments over the years. +| Amount of RAM installed in system | Recommended swap space | +| --------------------------------- | ---------------------- | +| ≤ 2GB | 2X RAM | +| 2GB – 8GB | = RAM | +| > 8GB | 8GB | + +Table 2: My recommended system swap space. + +It's possible that neither of these tables will work for your environment, but they will give you a place to start. The main consideration is that as the amount of RAM increases, adding more swap space simply leads to thrashing well before the swap space comes close to being filled. If you have too little virtual memory, you should add more RAM, if possible, rather than more swap space. + +In order to test the Fedora (and RHEL) swap space recommendations, I used its recommendation of **0.5*RAM** on my two largest systems (the ones with 32GB and 64GB of RAM). Even when running four or five VMs, multiple documents in LibreOffice, Thunderbird, the Chrome web browser, several terminal emulator sessions, the Xfe file manager, and a number of other background applications, the only time I see any use of swap is during backups I have scheduled for every morning at about 2am. Even then, swap usage is no more than 16MB—yes megabytes. These results are for my system with my loads and do not necessarily apply to your real-world environment. + +I recently had a conversation about swap space with some of the other Community Moderators here at [Opensource.com][2], and Chris Short, one of my friends in that illustrious and talented group, pointed me to an old [article][3] where he recommended using 1GB for swap space. This article was written in 2003, and he told me later that he now recommends zero swap space. + +So, we wondered, what you think? What do you recommend or use on your systems for swap space? + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/2/swap-space-poll + +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://docs.fedoraproject.org/en-US/fedora/f28/install-guide/ +[2]: http://Opensource.com +[3]: https://chrisshort.net/moving-to-linux-partitioning/ diff --git a/sources/tech/20190212 Ampersands and File Descriptors in Bash.md b/sources/tech/20190212 Ampersands and File Descriptors in Bash.md new file mode 100644 index 0000000000..ae0f2ce3f0 --- /dev/null +++ b/sources/tech/20190212 Ampersands and File Descriptors in Bash.md @@ -0,0 +1,162 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Ampersands and File Descriptors in Bash) +[#]: via: (https://www.linux.com/blog/learn/2019/2/ampersands-and-file-descriptors-bash) +[#]: author: (Paul Brown https://www.linux.com/users/bro66) + +Ampersands and File Descriptors in Bash +====== + + + +In our quest to examine all the clutter (`&`, `|`, `;`, `>`, `<`, `{`, `[`, `(`, ), `]`, `}`, etc.) that is peppered throughout most chained Bash commands, [we have been taking a closer look at the ampersand symbol (`&`)][1]. + +[Last time, we saw how you can use `&` to push processes that may take a long time to complete into the background][1]. But, the &, in combination with angle brackets, can also be used to pipe output and input elsewhere. + +In the [previous tutorials on][2] [angle brackets][3], you saw how to use `>` like this: + +``` +ls > list.txt +``` + +to pipe the output from `ls` to the _list.txt_ file. + +Now we see that this is really shorthand for + +``` +ls 1> list.txt +``` + +And that `1`, in this context, is a file descriptor that points to the standard output (`stdout`). + +In a similar fashion `2` points to standard error (`stderr`), and in the following command: + +``` +ls 2> error.log +``` + +all error messages are piped to the _error.log_ file. + +To recap: `1>` is the standard output (`stdout`) and `2>` the standard error output (`stderr`). + +There is a third standard file descriptor, `0<`, the standard input (`stdin`). You can see it is an input because the arrow (`<`) is pointing into the `0`, while for `1` and `2`, the arrows (`>`) are pointing outwards. + +### What are the standard file descriptors good for? + +If you are following this series in order, you have already used the standard output (`1>`) several times in its shorthand form: `>`. + +Things like `stderr` (`2`) are also handy when, for example, you know that your command is going to throw an error, but what Bash informs you of is not useful and you don't need to see it. If you want to make a directory in your _home/_ directory, for example: + +``` +mkdir newdir +``` + +and if _newdir/_ already exists, `mkdir` will show an error. But why would you care? (Ok, there some circumstances in which you may care, but not always.) At the end of the day, _newdir_ will be there one way or another for you to fill up with stuff. You can supress the error message by pushing it into the void, which is _/dev/null_ : + +``` +mkdir newdir 2> /dev/null +``` + +This is not just a matter of " _let's not show ugly and irrelevant error messages because they are annoying,_ " as there may be circumstances in which an error message may cause a cascade of errors elsewhere. Say, for example, you want to find all the _.service_ files under _/etc_. You could do this: + +``` +find /etc -iname "*.service" +``` + +But it turns out that on most systems, many of the lines spat out by `find` show errors because a regular user does not have read access rights to some of the folders under _/etc_. It makes reading the correct output cumbersome and, if `find` is part of a larger script, it could cause the next command in line to bork. + +Instead, you can do this: + +``` +find /etc -iname "*.service" 2> /dev/null +``` + +And you get only the results you are looking for. + +### A Primer on File Descriptors + +There are some caveats to having separate file descriptors for `stdout` and `stderr`, though. If you want to store the output in a file, doing this: + +``` +find /etc -iname "*.service" 1> services.txt +``` + +would work fine because `1>` means " _send standard output, and only standard output (NOT standard error) somewhere_ ". + +But herein lies a problem: what if you *do* want to keep a record within the file of the errors along with the non-erroneous results? The instruction above won't do that because it ONLY writes the correct results from `find`, and + +``` +find /etc -iname "*.service" 2> services.txt +``` + +will ONLY write the errors. + +How do we get both? Try the following command: + +``` +find /etc -iname "*.service" &> services.txt +``` + +... and say hello to `&` again! + +We have been saying all along that `stdin` (`0`), `stdout` (`1`), and `stderr` (`2`) are _file descriptors_. A file descriptor is a special construct that points to a channel to a file, either for reading, or writing, or both. This comes from the old UNIX philosophy of treating everything as a file. Want to write to a device? Treat it as a file. Want to write to a socket and send data over a network? Treat it as a file. Want to read from and write to a file? Well, obviously, treat it as a file. + +So, when managing where the output and errors from a command goes, treat the destination as a file. Hence, when you open them to read and write to them, they all get file descriptors. + +This has interesting effects. You can, for example, pipe contents from one file descriptor to another: + +``` +find /etc -iname "*.service" 1> services.txt 2>&1 +``` + +This pipes `stderr` to `stdout` and `stdout` is piped to a file, _services.txt_. + +And there it is again: the `&`, signaling to Bash that `1` is the destination file descriptor. + +Another thing with the standard file descriptors is that, when you pipe from one to another, the order in which you do this is a bit counterintuitive. Take the command above, for example. It looks like it has been written the wrong way around. You may be reading it like this: " _pipe the output to a file and then pipe errors to the standard output._ " It would seem the error output comes to late and is sent when `1` is already done. + +But that is not how file descriptors work. A file descriptor is not a placeholder for the file, but for the _input and/or output channel_ to the file. In this case, when you do `1> services.txt`, you are saying " _open a write channel to services.txt and leave it open_ ". `1` is the name of the channel you are going to use, and it remains open until the end of the line. + +If you still think it is the wrong way around, try this: + +``` +find /etc -iname "*.service" 2>&1 1>services.txt +``` + +And notice how it doesn't work; notice how errors get piped to the terminal and only the non-erroneous output (that is `stdout`) gets pushed to `services.txt`. + +That is because Bash processes every result from `find` from left to right. Think about it like this: when Bash gets to `2>&1`, `stdout` (`1`) is still a channel that points to the terminal. If the result that `find` feeds Bash contains an error, it is popped into `2`, transferred to `1`, and, away it goes, off to the terminal! + +Then at the end of the command, Bash sees you want to open `stdout` as a channel to the _services.txt_ file. If no error has occurred, the result goes through `1` into the file. + +By contrast, in + +``` +find /etc -iname "*.service" 1>services.txt 2>&1 +``` + +`1` is pointing at `services.txt` right from the beginning, so anything that pops into `2` gets piped through `1`, which is already pointing to the final resting place in `services.txt`, and that is why it works. + +In any case, as mentioned above `&>` is shorthand for " _both standard output and standard error_ ", that is, `2>&1`. + +This is probably all a bit much, but don't worry about it. Re-routing file descriptors here and there is commonplace in Bash command lines and scripts. And, you'll be learning more about file descriptors as we progress through this series. See you next week! + +-------------------------------------------------------------------------------- + +via: https://www.linux.com/blog/learn/2019/2/ampersands-and-file-descriptors-bash + +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/2019/2/and-ampersand-and-linux +[2]: https://www.linux.com/blog/learn/2019/1/understanding-angle-brackets-bash +[3]: https://www.linux.com/blog/learn/2019/1/more-about-angle-brackets-bash diff --git a/sources/tech/20190212 How To Check CPU, Memory And Swap Utilization Percentage In Linux.md b/sources/tech/20190212 How To Check CPU, Memory And Swap Utilization Percentage In Linux.md new file mode 100644 index 0000000000..0fadc0908d --- /dev/null +++ b/sources/tech/20190212 How To Check CPU, Memory And Swap Utilization Percentage In Linux.md @@ -0,0 +1,226 @@ +[#]: collector: (lujun9972) +[#]: translator: (An-DJ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How To Check CPU, Memory And Swap Utilization Percentage In Linux?) +[#]: via: (https://www.2daygeek.com/linux-check-cpu-memory-swap-utilization-percentage/) +[#]: author: (Vinoth Kumar https://www.2daygeek.com/author/vinoth/) + +How To Check CPU, Memory And Swap Utilization Percentage In Linux? +====== + +There is a lot of commands and options are available in Linux to check memory utilization but i don’t see much information to check about memory utilization percentage. + +Most of the times we are checking memory utilization alone and we won’t think about how much percentage is used. + +If you want to know those information then you are in the right page. + +We are here to help you out on this in details. + +This tutorial will help you to identify the memory utilization when you are facing high memory utilization frequently in Linux server. + +But the same time, you won’t be getting the clear utilization if you are using `free -m` or `free -g`. + +These format commands fall under Linux advanced commands. It will be very useful for Linux Experts and Middle Level Linux Users. + +### Method-1: How To Check Memory Utilization Percentage In Linux? + +We can use the following combination of commands to get this done. In this method, we are using combination of free and awk command to get the memory utilization percentage. + +If you are looking for other articles which is related to memory then navigate to the following link. Those are **[free Command][1]** , **[smem Command][2]** , **[ps_mem Command][3]** , **[vmstat Command][4]** and **[Multiple ways to check size of physical memory][5]**. + +For `Memory` Utilization Percentage without Percent Symbol: + +``` +$ free -t | awk 'NR == 2 {print "Current Memory Utilization is : " $3/$2*100}' +or +$ free -t | awk 'FNR == 2 {print "Current Memory Utilization is : " $3/$2*100}' + +Current Memory Utilization is : 20.4194 +``` + +For `Swap` Utilization Percentage without Percent Symbol: + +``` +$ free -t | awk 'NR == 3 {print "Current Swap Utilization is : " $3/$2*100}' +or +$ free -t | awk 'FNR == 3 {print "Current Swap Utilization is : " $3/$2*100}' + +Current Swap Utilization is : 0 +``` + +For `Memory` Utilization Percentage with Percent Symbol and two decimal places: + +``` +$ free -t | awk 'NR == 2 {printf("Current Memory Utilization is : %.2f%"), $3/$2*100}' +or +$ free -t | awk 'FNR == 2 {printf("Current Memory Utilization is : %.2f%"), $3/$2*100}' + +Current Memory Utilization is : 20.42% +``` + +For `Swap` Utilization Percentage with Percent Symbol and two decimal places: + +``` +$ free -t | awk 'NR == 3 {printf("Current Swap Utilization is : %.2f%"), $3/$2*100}' +or +$ free -t | awk 'FNR == 3 {printf("Current Swap Utilization is : %.2f%"), $3/$2*100}' + +Current Swap Utilization is : 0.00% +``` + +If you are looking for other articles which is related to memory then navigate to the following link. Those are **[Create/Extend Swap Partition using LVM][6]** , **[Multiple Ways To Create Or Extend Swap Space][7]** and **[Shell Script to automatically Create/Remove and Mount Swap File][8]**. + +free command output for better clarification: + +``` +$ free + total used free shared buff/cache available +Mem: 15867 3730 9868 1189 2269 10640 +Swap: 17454 0 17454 +Total: 33322 3730 27322 +``` + +Details are follow: + + * **`free:`** free is a standard command to check memory utilization in Linux. + * **`awk:`** awk is a powerful command which is specialized for textual data manipulation. + * **`FNR == 2:`** It gives the total number of records for each input file. Basically it’s used to select the given line (Here, it chooses the line number 2). + * **`NR == 2:`** It gives the total number of records processed. Basically it’s used to filter the given line (Here, it chooses the line number 2).. + * **`$3/$2*100:`** It divides column 2 with column 3 and it’s multiply the results with 100. + * **`printf:`** It used to format and print data. + * **`%.2f%:`** By default it prints floating point numbers with 6 decimal places. Use the following format to limit a decimal places. + + + +### Method-2: How To Check Memory Utilization Percentage In Linux? + +We can use the following combination of commands to get this done. In this method, we are using combination of free, grep and awk command to get the memory utilization percentage. + +For `Memory` Utilization Percentage without Percent Symbol: + +``` +$ free -t | grep Mem | awk '{print "Current Memory Utilization is : " $3/$2*100}' +Current Memory Utilization is : 20.4228 +``` + +For `Swap` Utilization Percentage without Percent Symbol: + +``` +$ free -t | grep Swap | awk '{print "Current Swap Utilization is : " $3/$2*100}' +Current Swap Utilization is : 0 +``` + +For `Memory` Utilization Percentage with Percent Symbol and two decimal places: + +``` +$ free -t | grep Mem | awk '{printf("Current Memory Utilization is : %.2f%"), $3/$2*100}' +Current Memory Utilization is : 20.43% +``` + +For `Swap` Utilization Percentage with Percent Symbol and two decimal places: + +``` +$ free -t | grep Swap | awk '{printf("Current Swap Utilization is : %.2f%"), $3/$2*100}' +Current Swap Utilization is : 0.00% +``` + +### Method-1: How To Check CPU Utilization Percentage In Linux? + +We can use the following combination of commands to get this done. In this method, we are using combination of top, print and awk command to get the CPU utilization percentage. + +If you are looking for other articles which is related to memory then navigate to the following link. Those are **[top Command][9]** , **[htop Command][10]** , **[atop Command][11]** and **[Glances Command][12]**. + +If it shows multiple CPU in the output then you need to use the following method. + +``` +$ top -b -n1 | grep ^%Cpu +%Cpu0 : 5.3 us, 0.0 sy, 0.0 ni, 94.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st +%Cpu1 : 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st +%Cpu2 : 0.0 us, 0.0 sy, 0.0 ni, 94.7 id, 0.0 wa, 0.0 hi, 5.3 si, 0.0 st +%Cpu3 : 5.3 us, 0.0 sy, 0.0 ni, 94.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st +%Cpu4 : 10.5 us, 15.8 sy, 0.0 ni, 73.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st +%Cpu5 : 0.0 us, 5.0 sy, 0.0 ni, 95.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st +%Cpu6 : 5.3 us, 0.0 sy, 0.0 ni, 94.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st +%Cpu7 : 5.3 us, 0.0 sy, 0.0 ni, 94.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st +``` + +For `CPU` Utilization Percentage without Percent Symbol: + +``` +$ top -b -n1 | grep ^%Cpu | awk '{cpu+=$9}END{print "Current CPU Utilization is : " 100-cpu/NR}' +Current CPU Utilization is : 21.05 +``` + +For `CPU` Utilization Percentage with Percent Symbol and two decimal places: + +``` +$ top -b -n1 | grep ^%Cpu | awk '{cpu+=$9}END{printf("Current CPU Utilization is : %.2f%"), 100-cpu/NR}' +Current CPU Utilization is : 14.81% +``` + +### Method-2: How To Check CPU Utilization Percentage In Linux? + +We can use the following combination of commands to get this done. In this method, we are using combination of top, print/printf and awk command to get the CPU utilization percentage. + +If it shows all together CPU(s) in the single output then you need to use the following method. + +``` +$ top -b -n1 | grep ^%Cpu +%Cpu(s): 15.3 us, 7.2 sy, 0.8 ni, 69.0 id, 6.7 wa, 0.0 hi, 1.0 si, 0.0 st +``` + +For `CPU` Utilization Percentage without Percent Symbol: + +``` +$ top -b -n1 | grep ^%Cpu | awk '{print "Current CPU Utilization is : " 100-$8}' +Current CPU Utilization is : 5.6 +``` + +For `CPU` Utilization Percentage with Percent Symbol and two decimal places: + +``` +$ top -b -n1 | grep ^%Cpu | awk '{printf("Current CPU Utilization is : %.2f%"), 100-$8}' +Current CPU Utilization is : 5.40% +``` + +Details are follow: + + * **`top:`** top is one of the best command to check currently running process on Linux system. + * **`-b:`** -b option, allow the top command to switch in batch mode. It is useful when you run the top command from local system to remote system. + * **`-n1:`** Number-of-iterations + * **`^%Cpu:`** Filter the lines which starts with %Cpu + * **`awk:`** awk is a powerful command which is specialized for textual data manipulation. + * **`cpu+=$9:`** For each line, add column 9 to a variable ‘cpu’. + * **`printf:`** It used to format and print data. + * **`%.2f%:`** By default it prints floating point numbers with 6 decimal places. Use the following format to limit a decimal places. + * **`100-cpu/NR:`** Finally print the ‘CPU Average’ by subtracting 100, divided by the number of records. + + + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/linux-check-cpu-memory-swap-utilization-percentage/ + +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/free-command-to-check-memory-usage-statistics-in-linux/ +[2]: https://www.2daygeek.com/smem-linux-memory-usage-statistics-reporting-tool/ +[3]: https://www.2daygeek.com/ps_mem-report-core-memory-usage-accurately-in-linux/ +[4]: https://www.2daygeek.com/linux-vmstat-command-examples-tool-report-virtual-memory-statistics/ +[5]: https://www.2daygeek.com/easy-ways-to-check-size-of-physical-memory-ram-in-linux/ +[6]: https://www.2daygeek.com/how-to-create-extend-swap-partition-in-linux-using-lvm/ +[7]: https://www.2daygeek.com/add-extend-increase-swap-space-memory-file-partition-linux/ +[8]: https://www.2daygeek.com/shell-script-create-add-extend-swap-space-linux/ +[9]: https://www.2daygeek.com/linux-top-command-linux-system-performance-monitoring-tool/ +[10]: https://www.2daygeek.com/linux-htop-command-linux-system-performance-resource-monitoring-tool/ +[11]: https://www.2daygeek.com/atop-system-process-performance-monitoring-tool/ +[12]: 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/20190212 Top 10 Best Linux Media Server Software.md b/sources/tech/20190212 Top 10 Best Linux Media Server Software.md new file mode 100644 index 0000000000..8fcea6343a --- /dev/null +++ b/sources/tech/20190212 Top 10 Best Linux Media Server Software.md @@ -0,0 +1,229 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Top 10 Best Linux Media Server Software) +[#]: via: (https://itsfoss.com/best-linux-media-server) +[#]: author: (Ankush Das https://itsfoss.com/author/ankush/) + +Top 10 Best Linux Media Server Software +====== + +Did someone tell you that Linux is just for programmers? That is so wrong! You have got a lot of great tools for [digital artists][1], [writers][2] and musicians. + +We have covered such tools in the past. Today it’s going to be slightly different. Instead of creating new digital content, let’s talk about consuming it. + +You have probably heard of media servers? Basically these software (and sometimes gadgets) allow you to view your local or cloud media (music, videos etc) in an intuitive interface. You can even use it to stream the content to other devices on your network. Sort of your personal Netflix. + +In this article, we will talk about the best media software available for Linux that you can use as a media player or as a media server software – as per your requirements. + +Some of these applications can also be used with Google’s Chromecast and Amazon’s Firestick. + +### Best Media Server Software for Linux + +![Best Media Server Software for Linux][3] + +The mentioned Linux media server software are in no particular order of ranking. + +I have tried to provide installation instructions for Ubuntu and Debian based distributions. It’s not possible to list installation steps for all Linux distributions for all the media servers mentioned here. Please take no offence for that. + +A couple of software in this list are not open source. If that’s the case, I have highlighted it appropriately. + +### 1\. Kodi + +![Kodi Media Server][4] + +Kod is one of the most popular media server software and player. Recently, Kodi 18.0 dropped in with a bunch of improvements that includes the support for Digital Rights Management (DRM) decryption, game emulators, ROMs, voice control, and more. + +It is a completely free and open source software. An active community for discussions and support exists as well. The user interface for Kodi is beautiful. I haven’t had the chance to use it in its early days – but I was amazed to see such a good UI for a Linux application. + +It has got great playback support – so you can add any supported 3rd party media service for the content or manually add the ripped video files to watch. + +#### How to install Kodi + +Type in the following commands in the terminal to install the latest version of Kodi via its [official PPA][5]. + +``` +sudo apt-get install software-properties-common +sudo add-apt-repository ppa:team-xbmc/ppa +sudo apt-get update +sudo apt-get install kodi +``` + +To know more about installing a development build or upgrading Kodi, refer to the [official installation guide][6]. + +### 2\. Plex + +![Plex Media Server][7] + +Plex is yet another impressive media player or could be used as a media server software. It is a great alternative to Kodi for the users who mostly utilize it to create an offline network of their media collection to sync and watch across multiple devices. + +Unlike Kodi, **Plex is not entirely open source**. It does offer a free account in order to use it. In addition, it offers premium pricing plans to unlock more features and have a greater control over your media while also being able to get a detailed insight on who/what/how Plex is being used. + +If you are an audiophile, you would love the integration of Plex with [TIDAL][8] music streaming service. You can also set up Live TV by adding it to your tuner. + +#### How to install Plex + +You can simply download the .deb file available on their official webpage and install it directly (or using [GDebi][9]) + +### 3\. Jellyfin + +![Emby media server][10] + +Yet another open source media server software with a bunch of features. [Jellyfin][11] is actually a fork of Emby media server. It may be one of the best out there available for ‘free’ but the multi-platform support still isn’t there yet. + +You can run it on a browser or utilize Chromecast – however – you will have to wait if you want the Android app or if you want it to support several devices. + +#### How to install Jellyfin + +Jellyfin provides a [detailed documentation][12] on how to install it from the binary packages/image available for Linux, Docker, and more. + +You will also find it easy to install it from the repository via the command line for Debian-based distribution. Check out their [installation guide][13] for more information. + +### 4\. LibreELEC + +![libreELEC][14] + +LibreELEC is an interesting media server software which is based on Kodi v18.0. They have recently released a new version (9.0.0) with a complete overhaul of the core OS support, hardware compatibility and user experience. + +Of course, being based on Kodi, it also has the DRM support. In addition, you can utilize its generic Linux builds or the special ones tailored for Raspberry Pi builds, WeTek devices, and more. + +#### How to install LibreELEC + +You can download the installer from their [official site][15]. For detailed instructions on how to use it, please refer to the [installation guide][16]. + +### 5\. OpenFLIXR Media Server + +![OpenFLIXR Media Server][17] + +Want something similar that compliments Plex media server but also compatible with VirtualBox or VMWare? You got it! + +OpenFLIXR is an automated media server software which integrates with Plex to provide all the features along with the ability to auto download TV shows and movies from Torrents. It even fetches the subtitles automatically giving you a seamless experience when coupled with Plex media software. + +You can also automate your home theater with this installed. In case you do not want to run it on a physical instance, it supports VMware, VirtualBox and Hyper-V as well. The best part is – it is an open source solution and based on Ubuntu Server. + +#### How to install OpenFLIXR + +The best way to do it is by installing VirtualBox – it will be easier. After you do that, just download it from the [official website][18] and import it. + +### 6\. MediaPortal + +![MediaPortal][19] + +MediaPortal is just another open source simple media server software with a decent user interface. It all depends on your personal preference – event though I would recommend Kodi over this. + +You can play DVDs, stream videos on your local network, and listen to music as well. It does not offer a fancy set of features but the ones you will mostly need. + +It gives you the option to choose from two different versions (one that is stable and the second which tries to incorporate new features – could be unstable). + +#### How to install MediaPotal + +Depending on what you want to setup (A TV-server only or a complete server setup), follow the [official setup guide][20] to install it properly. + +### 7\. Gerbera + +![Gerbera Media Center][21] + +A simple implementation for a media server to be able to stream using your local network. It does support transcoding which will convert the media in the format your device supports. + +If you have been following the options for media server form a very long time, then you might identify this as the rebranded (and improved) version of MediaTomb. Even though it is not a popular choice among the Linux users – it is still something usable when all fails or for someone who prefers a straightforward and a basic media server. + +#### How to install Gerbera + +Type in the following commands in the terminal to install it on any Ubuntu-based distro: + +``` +sudo apt install gerbera +``` + +For other Linux distributions, refer to the [documentation][22]. + +### 8\. OSMC (Open Source Media Center) + +![OSMC Open Source Media Center][23] + +It is an elegant-looking media server software originally based on Kodi media center. I was quite impressed with the user interface. It is simple and robust, being a free and open source solution. In a nutshell, all the essential features you would expect in a media server software. + +You can also opt in to purchase OSMC’s flagship device. It will play just about anything up to 4K standards with HD audio. In addition, it supports Raspberry Pi builds and 1st-gen Apple TV. + +#### How to install OSMC + +If your device is compatible, you can just select your operating system and download the device installer from the official [download page][24] and create a bootable image to install. + +### 9\. Universal Media Server + +![][25] + +Yet another simple addition to this list. Universal Media Server does not offer any fancy features but just helps you transcode / stream video and audio without needing much configuration. + +It supports Xbox 360, PS 3, and just about any other [DLNA][26]-capable devices. + +#### How to install Universal Media Center + +You can find all the packages listed on [FossHub][27] but you should follow the [official forum][28] to know more about how to install the package that you downloaded from the website. + +### 10\. Red5 Media Server + +![Red5 Media Server][29]Image Credit: [Red5 Server][30] + +A free and open source media server tailored for enterprise usage. You can use it for live streaming solutions – no matter if it is for entertainment or just video conferencing. + +They also offer paid licensing options for mobiles and high scalability. + +#### How to install Red5 + +Even though it is not the quickest installation method, follow the [installation guide on GitHub][31] to get started with the server without needing to tinker around. + +### Wrapping Up + +Every media server software listed here has its own advantages – you should pick one up and try the one which suits your requirement. + +Did we miss any of your favorite media server software? Let us know about it in the comments below! + + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/best-linux-media-server + +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/best-linux-graphic-design-software/ +[2]: https://itsfoss.com/open-source-tools-writers/ +[3]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/best-media-server-linux.png?resize=800%2C450&ssl=1 +[4]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/kodi-18-media-server.jpg?fit=800%2C450&ssl=1 +[5]: https://itsfoss.com/ppa-guide/ +[6]: https://kodi.wiki/view/HOW-TO:Install_Kodi_for_Linux +[7]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/plex.jpg?fit=800%2C368&ssl=1 +[8]: https://tidal.com/ +[9]: https://itsfoss.com/gdebi-default-ubuntu-software-center/ +[10]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/emby-server.jpg?fit=800%2C373&ssl=1 +[11]: https://jellyfin.github.io/ +[12]: https://jellyfin.readthedocs.io/en/latest/ +[13]: https://jellyfin.readthedocs.io/en/latest/administrator-docs/installing/ +[14]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/02/libreelec.jpg?resize=800%2C600&ssl=1 +[15]: https://libreelec.tv/downloads_new/ +[16]: https://libreelec.wiki/libreelec_usb-sd_creator +[17]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/openflixr-media-server.jpg?fit=800%2C449&ssl=1 +[18]: http://www.openflixr.com/#Download +[19]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/02/mediaportal.jpg?ssl=1 +[20]: https://www.team-mediaportal.com/wiki/display/MediaPortal1/Quick+Setup +[21]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/gerbera-server-softwarei.jpg?fit=800%2C583&ssl=1 +[22]: http://docs.gerbera.io/en/latest/install.html +[23]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/02/osmc-server.jpg?fit=800%2C450&ssl=1 +[24]: https://osmc.tv/download/ +[25]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/universal-media-server.jpg?ssl=1 +[26]: https://en.wikipedia.org/wiki/Digital_Living_Network_Alliance +[27]: https://www.fosshub.com/Universal-Media-Server.html?dwl=UMS-7.8.0.tgz +[28]: https://www.universalmediaserver.com/forum/viewtopic.php?t=10275 +[29]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/red5.jpg?resize=800%2C364&ssl=1 +[30]: https://www.red5server.com/ +[31]: https://github.com/Red5/red5-server/wiki/Installation-on-Linux +[32]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/best-media-server-linux.png?fit=800%2C450&ssl=1 diff --git a/sources/tech/20190213 How To Install, Configure And Use Fish Shell In Linux.md b/sources/tech/20190213 How To Install, Configure And Use Fish Shell In Linux.md new file mode 100644 index 0000000000..a03335c6b6 --- /dev/null +++ b/sources/tech/20190213 How To Install, Configure And Use Fish Shell In Linux.md @@ -0,0 +1,264 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How To Install, Configure And Use Fish Shell In Linux?) +[#]: via: (https://www.2daygeek.com/linux-fish-shell-friendly-interactive-shell/) +[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/) + +How To Install, Configure And Use Fish Shell In Linux? +====== + +Every Linux administrator might heard the word called shell. + +Do you know what is shell? Do you know what is the role for shell in Linux? How many shell is available in Linux? + +A shell is a program that provides an interface between a user and kernel. + +kernel is a heart of the Linux operating system that manage everything between user and operating system (OS). + +Shell is available for all the users when they launch the terminal. + +Once the terminal launched then user can run any commands which is available for him. + +When shell completes the command execution then you will be getting the output on the terminal window. + +Bash stands for Bourne Again Shell is the default shell which is running on most of the Linux distribution on today’s. + +It’s very popular and has a lot of features. Today we are going to discuss about the fish shell. + +### What Is Fish Shell? + +[Fish][1] stands for friendly interactive shell, is a fully-equipped, smart and user-friendly command line shell for Linux which comes with some handy features that is not available in most of the shell. + +The features are Autosuggestion, Sane Scripting, Man Page Completions, Web Based configuration and Glorious VGA Color. Are you curious to test it? if so, go ahead and install it by following the below installation steps. + +### How To Install Fish Shell In Linux? + +It’s very simple to install but it doesn’t available in most of the distributions except few. However, it can be easily installed by using the following [fish repository][2]. + +For **`Arch Linux`** based systems, use **[Pacman Command][3]** to install fish shell. + +``` +$ sudo pacman -S fish +``` + +For **`Ubuntu 16.04/18.04`** systems, use **[APT-GET Command][4]** or **[APT Command][5]** to install fish shell. + +``` +$ sudo apt-add-repository ppa:fish-shell/release-3 +$ sudo apt-get update +$ sudo apt-get install fish +``` + +For **`Fedora`** system, use **[DNF Command][6]** to install fish shell. + +For Fedora 29 System: + +``` +$ sudo dnf config-manager --add-repo https://download.opensuse.org/repositories/shells:/fish:/release:/3/Fedora_29/shells:fish:release:3.repo +$ sudo dnf install fish +``` + +For Fedora 28 System: + +``` +$ sudo dnf config-manager --add-repo https://download.opensuse.org/repositories/shells:/fish:/release:/3/Fedora_28/shells:fish:release:3.repo +$ sudo dnf install fish +``` + +For **`Debian`** systems, use **[APT-GET Command][4]** or **[APT Command][5]** to install fish shell. + +For Debian 9 System: + +``` +$ sudo wget -nv https://download.opensuse.org/repositories/shells:fish:release:3/Debian_9.0/Release.key -O Release.key +$ sudo apt-key add - < Release.key +$ sudo echo 'deb http://download.opensuse.org/repositories/shells:/fish:/release:/3/Debian_9.0/ /' > /etc/apt/sources.list.d/shells:fish:release:3.list +$ sudo apt-get update +$ sudo apt-get install fish +``` + +For Debian 8 System: + +``` +$ sudo wget -nv https://download.opensuse.org/repositories/shells:fish:release:3/Debian_8.0/Release.key -O Release.key +$ sudo apt-key add - < Release.key +$ sudo echo 'deb http://download.opensuse.org/repositories/shells:/fish:/release:/3/Debian_8.0/ /' > /etc/apt/sources.list.d/shells:fish:release:3.list +$ sudo apt-get update +$ sudo apt-get install fish +``` + +For **`RHEL/CentOS`** systems, use **[YUM Command][7]** to install fish shell. + +For RHEL 7 System: + +``` +$ sudo yum-config-manager --add-repo https://download.opensuse.org/repositories/shells:/fish:/release:/3/RHEL_7/shells:fish:release:3.repo +$ sudo yum install fish +``` + +For RHEL 6 System: + +``` +$ sudo yum-config-manager --add-repo https://download.opensuse.org/repositories/shells:/fish:/release:/3/RedHat_RHEL-6/shells:fish:release:3.repo +$ sudo yum install fish +``` + +For CentOS 7 System: + +``` +$ sudo yum-config-manager --add-repo https://download.opensuse.org/repositories/shells:fish:release:2/CentOS_7/shells:fish:release:2.repo +$ sudo yum install fish +``` + +For CentOS 6 System: + +``` +$ sudo yum-config-manager --add-repo https://download.opensuse.org/repositories/shells:fish:release:2/CentOS_6/shells:fish:release:2.repo +$ sudo yum install fish +``` + +For **`openSUSE Leap`** system, use **[Zypper Command][8]** to install fish shell. + +``` +$ sudo zypper addrepo https://download.opensuse.org/repositories/shells:/fish:/release:/3/openSUSE_Leap_42.3/shells:fish:release:3.repo +$ suod zypper refresh +$ sudo zypper install fish +``` + +### How To Use Fish Shell? + +Once you have successfully installed the fish shell. Simply type `fish` on your terminal, which will automatically switch to the fish shell from your default bash shell. + +``` +$ fish +``` + +![][10] + +### Auto Suggestions + +When you type any commands in the fish shell, it will auto suggest a command in a light grey color after typing few letters. +![][11] + +Once you got a suggestion then simple hit the `Left Arrow Mark` to complete it instead of typing the full command. +![][12] + +Instantly you can access the previous history based on the command by pressing `Up Arrow Mark` after typing a few letters. It’s similar to bash shell `CTRL+r` option. + +### Tab Completions + +If you would like to see if there are any other possibilities for the given command then simple press the `Tab` button once after typing a few letters. +![][13] + +Press the `Tab` button one more time to see the full lists. +![][14] + +### Syntax highlighting + +fish performs syntax highlighting, that you can see when you are typing any commands in the terminal. Invalid commands are colored by `RED color`. +![][15] + +The same way valid commands are shown in a different color. Also, fish will underline valid file paths when you type and it doesn’t show the underline if the path is not valid. +![][16] + +### Web based configuration + +There is a cool feature is available in the fish shell, that allow us to set colors, prompt, functions, variables, history and bindings via web browser. + +Run the following command on your terminal to start the web configuration interface. Simply press `Ctrl+c` to exit it. + +``` +$ fish_config +Web config started at 'file:///home/daygeek/.cache/fish/web_config-86ZF5P.html'. Hit enter to stop. +qt5ct: using qt5ct plugin +^C +Shutting down. +``` + +![][17] + +### Man Page Completions + +Other shells support programmable completions, but only fish generates them automatically by parsing your installed man pages. + +To do so, run the below command. + +``` +$ fish_update_completions +Parsing man pages and writing completions to /home/daygeek/.local/share/fish/generated_completions/ + 3466 / 3466 : zramctl.8.gz +``` + +### How To Set Fish as default shell + +If you would like to test the fish shell for some times then you can set the fish shell as your default shell instead of switching it every time. + +If so, first get the fish shell location by using the below command. + +``` +$ whereis fish +fish: /usr/bin/fish /etc/fish /usr/share/fish /usr/share/man/man1/fish.1.gz +``` + +Change your default shell as a fish shell by running the following command. + +``` +$ chsh -s /usr/bin/fish +``` + +![][18] + +`Make note:` Just verify whether the fish shell is added into `/etc/shells` directory or not. If no, then run the following command to append it. + +``` +$ echo /usr/bin/fish | sudo tee -a /etc/shells +``` + +Once you have done the testing and if you would like to come back to the bash shell permanently then use the following command. + +For temporary: + +``` +$ bash +``` + +For permanent: + +``` +$ chsh -s /bin/bash +``` + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/linux-fish-shell-friendly-interactive-shell/ + +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://fishshell.com/ +[2]: https://download.opensuse.org/repositories/shells:/fish:/release:/ +[3]: https://www.2daygeek.com/pacman-command-examples-manage-packages-arch-linux-system/ +[4]: https://www.2daygeek.com/apt-get-apt-cache-command-examples-manage-packages-debian-ubuntu-systems/ +[5]: https://www.2daygeek.com/apt-command-examples-manage-packages-debian-ubuntu-systems/ +[6]: https://www.2daygeek.com/dnf-command-examples-manage-packages-fedora-system/ +[7]: https://www.2daygeek.com/yum-command-examples-manage-packages-rhel-centos-systems/ +[8]: https://www.2daygeek.com/zypper-command-examples-manage-packages-opensuse-system/ +[9]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[10]: https://www.2daygeek.com/wp-content/uploads/2019/02/linux-fish-shell-friendly-interactive-shell-1.png +[11]: https://www.2daygeek.com/wp-content/uploads/2019/02/linux-fish-shell-friendly-interactive-shell-2.png +[12]: https://www.2daygeek.com/wp-content/uploads/2019/02/linux-fish-shell-friendly-interactive-shell-5.png +[13]: https://www.2daygeek.com/wp-content/uploads/2019/02/linux-fish-shell-friendly-interactive-shell-3.png +[14]: https://www.2daygeek.com/wp-content/uploads/2019/02/linux-fish-shell-friendly-interactive-shell-4.png +[15]: https://www.2daygeek.com/wp-content/uploads/2019/02/linux-fish-shell-friendly-interactive-shell-6.png +[16]: https://www.2daygeek.com/wp-content/uploads/2019/02/linux-fish-shell-friendly-interactive-shell-8.png +[17]: https://www.2daygeek.com/wp-content/uploads/2019/02/linux-fish-shell-friendly-interactive-shell-9.png +[18]: https://www.2daygeek.com/wp-content/uploads/2019/02/linux-fish-shell-friendly-interactive-shell-7.png diff --git a/sources/tech/20190213 How to build a WiFi picture frame with a Raspberry Pi.md b/sources/tech/20190213 How to build a WiFi picture frame with a Raspberry Pi.md new file mode 100644 index 0000000000..615f7620ed --- /dev/null +++ b/sources/tech/20190213 How to build a WiFi picture frame with a Raspberry Pi.md @@ -0,0 +1,135 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How to build a WiFi picture frame with a Raspberry Pi) +[#]: via: (https://opensource.com/article/19/2/wifi-picture-frame-raspberry-pi) +[#]: author: (Manuel Dewald https://opensource.com/users/ntlx) + +How to build a WiFi picture frame with a Raspberry Pi +====== +DIY a digital photo frame that streams photos from the cloud. + + + +Digital picture frames are really nice because they let you enjoy your photos without having to print them out. Plus, adding and removing digital files is a lot easier than opening a traditional frame and swapping the picture inside when you want to display a new photo. Even so, it's still a bit of overhead to remove your SD card, USB stick, or other storage from a digital picture frame, plug it into your computer, and copy new pictures onto it. + +An easier option is a digital picture frame that gets its pictures over WiFi, for example from a cloud service. Here's how to make one. + +### Gather your materials + + * Old [TFT][1] LCD screen + * HDMI-to-DVI cable (as the TFT screen supports DVI) + * Raspberry Pi 3 + * Micro SD card + * Raspberry Pi power supply + * Keyboard + * Mouse (optional) + + + +Connect the Raspberry Pi to the display using the cable and attach the power supply. + +### Install Raspbian + +**sudo raspi-config**. There I change the hostname (e.g., to **picframe** ) in Network Options and enable SSH to work remotely on the Raspberry Pi in Interfacing Options. Connect to the Raspberry Pi using (for example) . + +### Build and install the cloud client + +Download and flash Raspbian to the Micro SD card by following these [directions][2] . Plug the Micro SD card into the Raspberry Pi, boot it up, and configure your WiFi. My first action after a new Raspbian installation is usually running. There I change the hostname (e.g., to) in Network Options and enable SSH to work remotely on the Raspberry Pi in Interfacing Options. Connect to the Raspberry Pi using (for example) + +I use [Nextcloud][3] to synchronize my pictures, but you could use NFS, [Dropbox][4], or whatever else fits your needs to upload pictures to the frame. + +If you use Nextcloud, get a client for Raspbian by following these [instructions][5]. This is handy for placing new pictures on your picture frame and will give you the client application you may be familiar with on a desktop PC. When connecting the client application to your Nextcloud server, make sure to select only the folder where you'll store the images you want to be displayed on the picture frame. + +### Set up the slideshow + +The easiest way I've found to set up the slideshow is with a [lightweight slideshow project][6] built for exactly this purpose. There are some alternatives, like configuring a screensaver, but this application appears to be the simplest to set up. + +On your Raspberry Pi, download the binaries from the latest release, unpack them, and move them to an executable folder: + +``` +wget https://github.com/NautiluX/slide/releases/download/v0.9.0/slide_pi_stretch_0.9.0.tar.gz +tar xf slide_pi_stretch_0.9.0.tar.gz +mv slide_0.9.0/slide /usr/local/bin/ +``` + +Install the dependencies: + +``` +sudo apt install libexif12 qt5-default +``` + +Run the slideshow by executing the command below (don't forget to modify the path to your images). If you access your Raspberry Pi via SSH, set the **DISPLAY** variable to start the slideshow on the display attached to the Raspberry Pi. + +``` +DISPLAY=:0.0 slide -p /home/pi/nextcloud/picframe +``` + +### Autostart the slideshow + +To autostart the slideshow on Raspbian Stretch, create the following folder and add an **autostart** file to it: + +``` +mkdir -p /home/pi/.config/lxsession/LXDE/ +vi /home/pi/.config/lxsession/LXDE/autostart +``` + +Insert the following commands to autostart your slideshow. The **slide** command can be adjusted to your needs: + +``` +@xset s noblank +@xset s off +@xset -dpms +@slide -p -t 60 -o 200 -p /home/pi/nextcloud/picframe +``` + +Disable screen blanking, which the Raspberry Pi normally does after 10 minutes, by editing the following file: + +``` +vi /etc/lightdm/lightdm.conf +``` + +and adding these two lines to the end: + +``` +[SeatDefaults] +xserver-command=X -s 0 -dpms +``` + +### Configure a power-on schedule + +You can schedule your picture frame to turn on and off at specific times by using two simple cronjobs. For example, say you want it to turn on automatically at 7 am and turn off at 11 pm. Run **crontab -e** and insert the following two lines. + +``` +0 23 * * * /opt/vc/bin/tvservice -o + +0 7 * * * /opt/vc/bin/tvservice -p && sudo systemctl restart display-manager +``` + +Note that this won't turn the Raspberry Pi power's on and off; it will just turn off HDMI, which will turn the screen off. The first line will power off HDMI at 11 pm. The second line will bring the display back up and restart the display manager at 7 am. + +### Add a final touch + +By following these simple steps, you can create your own WiFi picture frame. If you want to give it a nicer look, build a wooden frame for the display. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/2/wifi-picture-frame-raspberry-pi + +作者：[Manuel Dewald][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/ntlx +[b]: https://github.com/lujun9972 +[1]: https://en.wikipedia.org/wiki/Thin-film-transistor_liquid-crystal_display +[2]: https://www.raspberrypi.org/documentation/installation/installing-images/README.md +[3]: https://nextcloud.com/ +[4]: http://dropbox.com/ +[5]: https://github.com/nextcloud/client_theming#building-on-debian +[6]: https://github.com/NautiluX/slide/releases/tag/v0.9.0 diff --git a/sources/tech/20190214 Run Particular Commands Without Sudo Password In Linux.md b/sources/tech/20190214 Run Particular Commands Without Sudo Password In Linux.md new file mode 100644 index 0000000000..df5bfddb3a --- /dev/null +++ b/sources/tech/20190214 Run Particular Commands Without Sudo Password In Linux.md @@ -0,0 +1,157 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Run Particular Commands Without Sudo Password In Linux) +[#]: via: (https://www.ostechnix.com/run-particular-commands-without-sudo-password-linux/) +[#]: author: (SK https://www.ostechnix.com/author/sk/) + +Run Particular Commands Without Sudo Password In Linux +====== + +I had a script on my Ubuntu system deployed on AWS. The primary purpose of this script is to check if a specific service is running at regular interval (every one minute to be precise) and start that service automatically if it is stopped for any reason. But the problem is I need sudo privileges to start the service. As you may know already, we should provide password when we run something as sudo user. But I don’t want to do that. What I actually want to do is to run the service as sudo without password. If you’re ever in a situation like this, I know a small work around, Today, in this brief guide, I will teach you how to run particular commands without sudo password in Unix-like operating systems. + +Have a look at the following example. + +``` +$ sudo mkdir /ostechnix +[sudo] password for sk: +``` + +![][2] + +As you can see in the above screenshot, I need to provide sudo password when creating a directory named ostechnix in root (/) folder. Whenever we try to execute a command with sudo privileges, we must enter the password. However, in my scenario, I don’t want to provide the sudo password. Here is what I did to run a sudo command without password on my Linux box. + +### Run Particular Commands Without Sudo Password In Linux + +For any reasons, if you want to allow a user to run a particular command without giving the sudo password, you need to add that command in **sudoers** file. + +I want the user named **sk** to execute **mkdir** command without giving the sudo password. Let us see how to do it. + +Edit sudoers file: + +``` +$ sudo visudo +``` + +Add the following line at the end of file. + +``` +sk ALL=NOPASSWD:/bin/mkdir +``` + +![][3] + +Here, **sk** is the username. As per the above line, the user **sk** can run ‘mkdir’ command from any terminal, without sudo password. + +You can add additional commands (for example **chmod** ) with comma-separated values as shown below. + +``` +sk ALL=NOPASSWD:/bin/mkdir,/bin/chmod +``` + +Save and close the file. Log out (or reboot) your system. Now, log in as normal user ‘sk’ and try to run those commands with sudo and see what happens. + +``` +$ sudo mkdir /dir1 +``` + +![][4] + +See? Even though I ran ‘mkdir’ command with sudo privileges, there was no password prompt. From now on, the user **sk** need not to enter the sudo password while running ‘mkdir’ command. + +When running all other commands except those commands added in sudoers files, you will be prompted to enter the sudo password. + +Let us run another command with sudo. + +``` +$ sudo apt update +``` + +![][5] + +See? This command prompts me to enter the sudo password. + +If you don’t want this command to prompt you to ask sudo password, edit sudoers file: + +``` +$ sudo visudo +``` + +Add the ‘apt’ command in visudo file like below: + +``` +sk ALL=NOPASSWD: /bin/mkdir,/usr/bin/apt +``` + +Did you notice that the apt binary executable file path is different from mkdir? Yes, you must provide the correct executable file path. To find executable file path of any command, for example ‘apt’, use ‘whereis’ command like below. + +``` +$ whereis apt +apt: /usr/bin/apt /usr/lib/apt /etc/apt /usr/share/man/man8/apt.8.gz +``` + +As you see, the executable file for apt command is **/usr/bin/apt** , hence I added it in sudoers file. + +Like I already mentioned, you can add any number of commands with comma-separated values. Save and close your sudoers file once you’re done. Log out and log in again to your system. + +Now, check if you can be able to run the command with sudo prefix without using the password: + +``` +$ sudo apt update +``` + +![][6] + +See? The apt command didn’t ask me the password even though I ran it with sudo. + +Here is yet another example. If you want to run a specific service, for example apache2, add it as shown below. + +``` +sk ALL=NOPASSWD:/bin/mkdir,/usr/bin/apt,/bin systemctl restart apache2 +``` + +Now, the user can run ‘sudo systemctl restart apache2’ command without sudo password. + +Can I re-authenticate to a particular command in the above case? Of course, yes! Just remove the added command. Log out and log in back. + +Alternatively, you can add **‘PASSWD:’** directive in-front of the command. Look at the following example. + +Add/modify the following line as shown below. + +``` +sk ALL=NOPASSWD:/bin/mkdir,/bin/chmod,PASSWD:/usr/bin/apt +``` + +In this case, the user **sk** can run ‘mkdir’ and ‘chmod’ commands without entering the sudo password. However, he must provide sudo password when running ‘apt’ command. + +**Disclaimer:** This is for educational-purpose only. You should be very careful while applying this method. This method might be both productive and destructive. Say for example, if you allow users to execute ‘rm’ command without sudo password, they could accidentally or intentionally delete important stuffs. You have been warned! + +**Suggested read:** + +And, that’s all for now. Hope this was useful. More good stuffs to come. Stay tuned! + +Cheers! + + + +-------------------------------------------------------------------------------- + +via: https://www.ostechnix.com/run-particular-commands-without-sudo-password-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]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[2]: http://www.ostechnix.com/wp-content/uploads/2017/05/sudo-password-1.png +[3]: http://www.ostechnix.com/wp-content/uploads/2017/05/sudo-password-7.png +[4]: http://www.ostechnix.com/wp-content/uploads/2017/05/sudo-password-6.png +[5]: http://www.ostechnix.com/wp-content/uploads/2017/05/sudo-password-4.png +[6]: http://www.ostechnix.com/wp-content/uploads/2017/05/sudo-password-5.png diff --git a/sources/tech/20190215 4 Methods To Change The HostName In Linux.md b/sources/tech/20190215 4 Methods To Change The HostName In Linux.md new file mode 100644 index 0000000000..ad95e05fae --- /dev/null +++ b/sources/tech/20190215 4 Methods To Change The HostName In Linux.md @@ -0,0 +1,227 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (4 Methods To Change The HostName In Linux) +[#]: via: (https://www.2daygeek.com/four-methods-to-change-the-hostname-in-linux/) +[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/) + +4 Methods To Change The HostName In Linux +====== + +We had written an article yesterday in our website about **[changing hostname in Linux][1]**. + +Today we are going to show you that how to change the hostname using different methods. You can choose the best one for you. + +systemd systems comes with a handy tool called `hostnamectl` that allow us to manage the system hostname easily. + +It’s changing the hostname instantly and doesn’t required reboot when you use the native commands. + +But if you modify the hostname manually in any of the configuration file that requires reboot. + +In this article we will show you the four methods to change the hostname in systemd system. + +hostnamectl command allows to set three kind of hostname in Linux and the details are below. + + * **`Static:`** It’s static hostname which is added by the system admin. + * **`Transient/Dynamic:`** It’s assigned by DHCP or DNS server at run time. + * **`Pretty:`** It can be assigned by the system admin. It is a free-form of the hostname that represent the server in the pretty way like, “JBOSS UAT Server”. + + + +It can be done in the following four methods. + + * **`hostnamectl Command:`** hostnamectl command is controling the system hostname. + * **`nmcli Command:`** nmcli is a command-line tool for controlling NetworkManager. + * **`nmtui Command:`** nmtui is a text User Interface for controlling NetworkManager. + * **`/etc/hostname file:`** This file is containing the static system hostname. + + + +### Method-1: Change The HostName Using hostnamectl Command in Linux + +hostnamectl may be used to query and change the system hostname and related settings. + +Simple run the `hostnamectl` command to view the system hostname. + +``` +$ hostnamectl +or +$ hostnamectl status + + Static hostname: daygeek-Y700 + Icon name: computer-laptop + Chassis: laptop + Machine ID: 31bdeb7b83230a2025d43547368d75bc + Boot ID: 267f264c448f000ea5aed47263c6de7f + Operating System: Manjaro Linux + Kernel: Linux 4.19.20-1-MANJARO + Architecture: x86-64 +``` + +If you would like to change the hostname, use the following command format. + +**The general syntax:** + +``` +$ hostnamectl set-hostname [YOUR NEW HOSTNAME] +``` + +Use the following command to change the hostname using hostnamectl command. In this example, i’m going to change the hostname from `daygeek-Y700` to `magi-laptop`. + +``` +$ hostnamectl set-hostname magi-laptop +``` + +You can view the updated hostname by running the following command. + +``` +$ hostnamectl + Static hostname: magi-laptop + Icon name: computer-laptop + Chassis: laptop + Machine ID: 31bdeb7b83230a2025d43547368d75bc + Boot ID: 267f264c448f000ea5aed47263c6de7f + Operating System: Manjaro Linux + Kernel: Linux 4.19.20-1-MANJARO + Architecture: x86-64 +``` + +### Method-2: Change The HostName Using nmcli Command in Linux + +nmcli is a command-line tool for controlling NetworkManager and reporting network status. + +nmcli is used to create, display, edit, delete, activate, and deactivate network connections, as well as control and display network device status. Also, it allow us to change the hostname. + +Use the following format to view the current hostname using nmcli. + +``` +$ nmcli general hostname +daygeek-Y700 +``` + +**The general syntax:** + +``` +$ nmcli general hostname [YOUR NEW HOSTNAME] +``` + +Use the following command to change the hostname using nmcli command. In this example, i’m going to change the hostname from `daygeek-Y700` to `magi-laptop`. + +``` +$ nmcli general hostname magi-laptop +``` + +It’s taking effect without bouncing the below service. However, for safety purpose just restart the systemd-hostnamed service for the changes to take effect. + +``` +$ sudo systemctl restart systemd-hostnamed +``` + +Again run the same nmcli command to check the changed hostname. + +``` +$ nmcli general hostname +magi-laptop +``` + +### Method-3: Change The HostName Using nmtui Command in Linux + +nmtui is a curses‐based TUI application for interacting with NetworkManager. When starting nmtui, the user is prompted to choose the activity to perform unless it was specified as the first argument. + +Run the following command on terminal to launch the terminal user interface. + +``` +$ nmtui +``` + +Use the `Down Arrow Mark` to choose the `Set system hostname` option then hit the `Enter` button. +![][3] + +This is old hostname screenshot. +![][4] + +Just remove the olde one and update the new one then hit `OK` button. +![][5] + +It will show you the updated hostname in the screen and simple hit `OK` button to complete it. +![][6] + +Finally hit the `Quit` button to exit from the nmtui terminal. +![][7] + +It’s taking effect without bouncing the below service. However, for safety purpose just restart the systemd-hostnamed service for the changes to take effect. + +``` +$ sudo systemctl restart systemd-hostnamed +``` + +You can view the updated hostname by running the following command. + +``` +$ hostnamectl + Static hostname: daygeek-Y700 + Icon name: computer-laptop + Chassis: laptop + Machine ID: 31bdeb7b83230a2025d43547368d75bc + Boot ID: 267f264c448f000ea5aed47263c6de7f + Operating System: Manjaro Linux + Kernel: Linux 4.19.20-1-MANJARO + Architecture: x86-64 +``` + +### Method-4: Change The HostName Using /etc/hostname File in Linux + +Alternatively, we can change the hostname by modifying the `/etc/hostname` file. But this method +requires server reboot for changes to take effect. + +Check the current hostname using /etc/hostname file. + +``` +$ cat /etc/hostname +daygeek-Y700 +``` + +To change the hostname, simple overwrite the file because it’s contains only the hostname alone. + +``` +$ sudo echo "magi-daygeek" > /etc/hostname + +$ cat /etc/hostname +magi-daygeek +``` + +Reboot the system by running the following command. + +``` +$ sudo init 6 +``` + +Finally verify the updated hostname using /etc/hostname file. + +``` +$ cat /etc/hostname +magi-daygeek +``` + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/four-methods-to-change-the-hostname-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 +[1]: https://www.2daygeek.com/linux-change-set-hostname/ +[2]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[3]: https://www.2daygeek.com/wp-content/uploads/2019/02/four-methods-to-change-the-hostname-in-linux-1.png +[4]: https://www.2daygeek.com/wp-content/uploads/2019/02/four-methods-to-change-the-hostname-in-linux-2.png +[5]: https://www.2daygeek.com/wp-content/uploads/2019/02/four-methods-to-change-the-hostname-in-linux-3.png +[6]: https://www.2daygeek.com/wp-content/uploads/2019/02/four-methods-to-change-the-hostname-in-linux-4.png +[7]: https://www.2daygeek.com/wp-content/uploads/2019/02/four-methods-to-change-the-hostname-in-linux-5.png diff --git a/sources/tech/20190215 Make websites more readable with a shell script.md b/sources/tech/20190215 Make websites more readable with a shell script.md new file mode 100644 index 0000000000..06b748cfb5 --- /dev/null +++ b/sources/tech/20190215 Make websites more readable with a shell script.md @@ -0,0 +1,258 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Make websites more readable with a shell script) +[#]: via: (https://opensource.com/article/19/2/make-websites-more-readable-shell-script) +[#]: author: (Jim Hall https://opensource.com/users/jim-hall) + +Make websites more readable with a shell script +====== +Calculate the contrast ratio between your website's text and background to make sure your site is easy to read. + + + +If you want people to find your website useful, they need to be able to read it. The colors you choose for your text can affect the readability of your site. Unfortunately, a popular trend in web design is to use low-contrast colors when printing text, such as gray text on a white background. Maybe that looks really cool to the web designer, but it is really hard for many of us to read. + +The W3C provides Web Content Accessibility Guidelines, which includes guidance to help web designers pick text and background colors that can be easily distinguished from each other. This is called the "contrast ratio." The W3C definition of the contrast ratio requires several calculations: given two colors, you first compute the relative luminance of each, then calculate the contrast ratio. The ratio will fall in the range 1 to 21 (typically written 1:1 to 21:1). The higher the contrast ratio, the more the text will stand out against the background. For example, black text on a white background is highly visible and has a contrast ratio of 21:1. And white text on a white background is unreadable at a contrast ratio of 1:1. + +The [W3C says body text][1] should have a contrast ratio of at least 4.5:1 with headings at least 3:1. But that seems to be the bare minimum. The W3C also recommends at least 7:1 for body text and at least 4.5:1 for headings. + +Calculating the contrast ratio can be a chore, so it's best to automate it. I've done that with this handy Bash script. In general, the script does these things: + + 1. Gets the text color and background color + 2. Computes the relative luminance of each + 3. Calculates the contrast ratio + + + +### Get the colors + +You may know that every color on your monitor can be represented by red, green, and blue (R, G, and B). To calculate the relative luminance of a color, my script will need to know the red, green, and blue components of the color. Ideally, my script would read this information as separate R, G, and B values. Web designers might know the specific RGB code for their favorite colors, but most humans don't know RGB values for the different colors. Instead, most people reference colors by names like "red" or "gold" or "maroon." + +Fortunately, the GNOME [Zenity][2] tool has a color-picker app that lets you use different methods to select a color, then returns the RGB values in a predictable format of "rgb( **R** , **G** , **B** )". Using Zenity makes it easy to get a color value: + +``` +color=$( zenity --title 'Set text color' --color-selection --color='black' ) +``` + +In case the user (accidentally) clicks the Cancel button, the script assumes a color: + +``` +if [ $? -ne 0 ] ; then + echo '** color canceled .. assume black' + color='rgb(0,0,0)' +fi +``` + +My script does something similar to set the background color value as **$background**. + +### Compute the relative luminance + +Once you have the foreground color in **$color** and the background color in **$background** , the next step is to compute the relative luminance for each. On its website, the [W3C provides an algorithm][3] to compute the relative luminance of a color. + +> For the sRGB colorspace, the relative luminance of a color is defined as +> **L = 0.2126 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated R + 0.7152 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated G + 0.0722 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated B** where R, G and B are defined as: +> +> if RsRGB <= 0.03928 then R = RsRGB/12.92 +> else R = ((RsRGB+0.055)/1.055) ^ 2.4 +> +> if GsRGB <= 0.03928 then G = GsRGB/12.92 +> else G = ((GsRGB+0.055)/1.055) ^ 2.4 +> +> if BsRGB <= 0.03928 then B = BsRGB/12.92 +> else B = ((BsRGB+0.055)/1.055) ^ 2.4 +> +> and RsRGB, GsRGB, and BsRGB are defined as: +> +> RsRGB = R8bit/255 +> +> GsRGB = G8bit/255 +> +> BsRGB = B8bit/255 + +Since Zenity returns color values in the format "rgb( **R** , **G** , **B** )," the script can easily pull apart the R, B, and G values to compute the relative luminance. AWK makes this a simple task, using the comma as the field separator ( **-F,** ) and using AWK's **substr()** string function to pick just the text we want from the "rgb( **R** , **G** , **B** )" color value: + +``` +R=$( echo $color | awk -F, '{print substr($1,5)}' ) +G=$( echo $color | awk -F, '{print $2}' ) +B=$( echo $color | awk -F, '{n=length($3); print substr($3,1,n-1)}' ) +``` + +**(For more on extracting and displaying data with AWK,[Get our AWK cheat sheet][4].)** + +Calculating the final relative luminance is best done using the BC calculator. BC supports the simple if-then-else needed in the calculation, which makes this part simple. But since BC cannot directly calculate exponentiation using a non-integer exponent, we need to do some extra math using the natural logarithm instead: + +``` +echo "scale=4 +rsrgb=$R/255 +gsrgb=$G/255 +bsrgb=$B/255 +if ( rsrgb <= 0.03928 ) r = rsrgb/12.92 else r = e( 2.4 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated l((rsrgb+0.055)/1.055) ) +if ( gsrgb <= 0.03928 ) g = gsrgb/12.92 else g = e( 2.4 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated l((gsrgb+0.055)/1.055) ) +if ( bsrgb <= 0.03928 ) b = bsrgb/12.92 else b = e( 2.4 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated l((bsrgb+0.055)/1.055) ) +0.2126 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated r + 0.7152 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated g + 0.0722 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated b" | bc -l +``` + +This passes several instructions to BC, including the if-then-else statements that are part of the relative luminance formula. BC then prints the final value. + +### Calculate the contrast ratio + +With the relative luminance of the text color and the background color, now the script can calculate the contrast ratio. The [W3C determines the contrast ratio][5] with this formula: + +> (L1 + 0.05) / (L2 + 0.05), where +> L1 is the relative luminance of the lighter of the colors, and +> L2 is the relative luminance of the darker of the colors + +Given two relative luminance values **$r1** and **$r2** , it's easy to calculate the contrast ratio using the BC calculator: + +``` +echo "scale=2 +if ( $r1 > $r2 ) { l1=$r1; l2=$r2 } else { l1=$r2; l2=$r1 } +(l1 + 0.05) / (l2 + 0.05)" | bc +``` + +This uses an if-then-else statement to determine which value ( **$r1** or **$r2** ) is the lighter or darker color. BC performs the resulting calculation and prints the result, which the script can store in a variable. + +### The final script + +With the above, we can pull everything together into a final script. I use Zenity to display the final result in a text box: + +``` +#!/bin/sh +# script to calculate contrast ratio of colors + +# read color and background color: +# zenity returns values like 'rgb(255,140,0)' and 'rgb(255,255,255)' + +color=$( zenity --title 'Set text color' --color-selection --color='black' ) +if [ $? -ne 0 ] ; then + echo '** color canceled .. assume black' + color='rgb(0,0,0)' +fi + +background=$( zenity --title 'Set background color' --color-selection --color='white' ) +if [ $? -ne 0 ] ; then + echo '** background canceled .. assume white' + background='rgb(255,255,255)' +fi + +# compute relative luminance: + +function luminance() +{ + R=$( echo $1 | awk -F, '{print substr($1,5)}' ) + G=$( echo $1 | awk -F, '{print $2}' ) + B=$( echo $1 | awk -F, '{n=length($3); print substr($3,1,n-1)}' ) + + echo "scale=4 +rsrgb=$R/255 +gsrgb=$G/255 +bsrgb=$B/255 +if ( rsrgb <= 0.03928 ) r = rsrgb/12.92 else r = e( 2.4 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated l((rsrgb+0.055)/1.055) ) +if ( gsrgb <= 0.03928 ) g = gsrgb/12.92 else g = e( 2.4 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated l((gsrgb+0.055)/1.055) ) +if ( bsrgb <= 0.03928 ) b = bsrgb/12.92 else b = e( 2.4 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated l((bsrgb+0.055)/1.055) ) +0.2126 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated r + 0.7152 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated g + 0.0722 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated b" | bc -l +} + +lum1=$( luminance $color ) +lum2=$( luminance $background ) + +# compute contrast + +function contrast() +{ + echo "scale=2 +if ( $1 > $2 ) { l1=$1; l2=$2 } else { l1=$2; l2=$1 } +(l1 + 0.05) / (l2 + 0.05)" | bc +} + +rel=$( contrast $lum1 $lum2 ) + +# print results + +( cat< + +If you like Linux related videos, please [subscribe to our YouTube channel][7]. + +Once you have installed FinalCrypt, you’ll find it in your list of installed applications. Launch it from there. + +Upon launch, you will observe two sections (split) for the items to encrypt/decrypt and the other to select the OTP file. + +![Using FinalCrypt for encrypting files in Linux][8] + +First, you will have to generate an OTP key. Here’s how to do that: + +![finalcrypt otp][9] + +Do note that your file name can be anything – but you need to make sure that the key file size is greater or equal to the file you want to encrypt. I find it absurd but that’s how it is. + +![][10] + +After you generate the file, select the key on the right-side of the window and then select the files that you want to encrypt on the left-side of the window. + +You will find the checksum value, key file size, and valid status highlighted after generating the OTP: + +![][11] + +After making the selection, you just need to click on “ **Encrypt** ” to encrypt those files and if already encrypted, then “ **Decrypt** ” to decrypt those. + +![][12] + +You can also use FinalCrypt in command line to automate your encryption job. + +#### How do you secure your OTP key? + +It is easy to encrypt/decrypt the files you want to protect. But, where should you keep your OTP key? + +It is literally useless if you fail to keep your OTP key in a safe storage location. + +Well, one of the best ways would be to use a USB stick specifically for the keys you want to store. Just plug it in when you want to decrypt files and its all good. + +In addition to that, you may save your key on a [cloud service][13], if you consider it secure enough. + +More information about FinalCrypt can be found on its website. + +[FinalCrypt](https://sites.google.com/site/ronuitholland/home/finalcrypt) + +**Wrapping Up** + +It might seem a little overwhelming at the beginning but it is actually a simple and user-friendly encryption program available for Linux. There are other programs to [password protect folders][14] as well if you are interested in some additional reading. + +What do you think about FinalCrypt? Do you happen to know about something similar which is potentially better? Let us know in the comments and we shall take a look at them! + + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/finalcrypt/ + +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.gnupg.org/ +[2]: https://itsfoss.com/encryptpad-encrypted-text-editor-linux/ +[3]: https://github.com/ron-from-nl/FinalCrypt +[4]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/finalcrypt.png?resize=800%2C450&ssl=1 +[5]: https://en.wikipedia.org/wiki/One-time_pad +[6]: https://itsfoss.com/install-deb-files-ubuntu/ +[7]: https://www.youtube.com/c/itsfoss?sub_confirmation=1 +[8]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/finalcrypt.jpg?fit=800%2C439&ssl=1 +[9]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/02/finalcrypt-otp-key.jpg?resize=800%2C443&ssl=1 +[10]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/finalcrypt-otp-generate.jpg?ssl=1 +[11]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/finalcrypt-key.jpg?fit=800%2C420&ssl=1 +[12]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/finalcrypt-encrypt.jpg?ssl=1 +[13]: https://itsfoss.com/cloud-services-linux/ +[14]: https://itsfoss.com/password-protect-folder-linux/ +[15]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/finalcrypt.png?fit=800%2C450&ssl=1 diff --git a/sources/tech/20190217 Install Android 8.1 Oreo on Linux To Run Apps - Games.md b/sources/tech/20190217 Install Android 8.1 Oreo on Linux To Run Apps - Games.md new file mode 100644 index 0000000000..88798037c5 --- /dev/null +++ b/sources/tech/20190217 Install Android 8.1 Oreo on Linux To Run Apps - Games.md @@ -0,0 +1,208 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Install Android 8.1 Oreo on Linux To Run Apps & Games) +[#]: via: (https://fosspost.org/tutorials/install-android-8-1-oreo-on-linux) +[#]: author: (Python Programmer;Open Source Software Enthusiast. Worked On Developing A Lot Of Free Software. The Founder Of Foss Post;Foss Project. Computer Science Major. ) + +Install Android 8.1 Oreo on Linux To Run Apps & Games +====== + + + +[android x86][1] is a free and an open source project to port the android system made by Google from the ARM architecture to the x86 architecture, which allow users to run the android system on their desktop machines to enjoy all android functionalities + Apps & games. + +The android x86 project finished porting the android 8.1 Oreo system to the x86 architecture few weeks ago. In this post, we’ll explain how to install it on your Linux system so that you can use your android apps and games any time you want. + +### Installing Android x86 8.1 Oreo on Linux + +#### Preparing the Environment + +First, let’s download the android x86 8.1 Oreo system image. You can download it from [this page][2], just click on the “View” button under the android-x86_64-8.1-r1.iso file. + +We are going to use QEMU to run android x86 on our Linux system. QEMU is a very good emulator software, which is also free and open source, and is available in all the major Linux distributions repositories. + +To install QEMU on Ubuntu/Linux Mint/Debian: + +``` +sudo apt-get install qemu qemu-kvm libvirt-bin +``` + +To install QEMU on Fedora: + +``` +sudo dnf install qemu qemu-kvm +``` + +For other distributions, just search for the qemu and qemu-kvm packages and install them. + +After you have installed QEMU, we’ll need to run the following command to create the android.img file, which will be like some sort of an allocated disk space just for the android system. All android files and system will be inside that image file: + +``` +qemu-img create -f qcow2 android.img 15G +``` + +Here we are saying that we want to allocate a maximum of 15GB for android, but you can change it to any size you want (make sure it’s at least bigger than 5GB). + +Now, to start running the android system for the first time, run: + +``` +sudo qemu-system-x86_64 -m 2048 -boot d -enable-kvm -smp 3 -net nic -net user -hda android.img -cdrom /home/mhsabbagh/android-x86_64-8.1-r1.iso +``` + +Replace /home/mhsabbagh/android-x86_64-8.1-r1.iso with the path of the file that you downloaded from the android x86 website. For explaination of other options we are using here, you may refer to [this article][3]. + +After you run the above command, the android system will start: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 39 android 8.1 oreo on linux][4] + +#### Installing the System + +From this window, choose “Advanced options”, which should lead to the following menu, from which you should choose “Auto_installation” as follows: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 41 android 8.1 oreo on linux][5] + +After that, the installer will just tell you about whether you want to continue or not, choose Yes: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 43 android 8.1 oreo on linux][6] + +And the installation will carry on without any further instructions from you: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 45 android 8.1 oreo on linux][7] + +Finally you’ll receive this message, which indicates that you have successfully installed android 8.1: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 47 android 8.1 oreo on linux][8] + +For now, just close the QEMU window completely. + +#### Booting and Using Android 8.1 Oreo + +Now that the android system is fully installed in your android.img file, you should use the following QEMU command to start it instead of the previous one: + +``` +sudo qemu-system-x86_64 -m 2048 -boot d -enable-kvm -smp 3 -net nic -net user -hda android.img +``` + +Notice that all we did was that we just removed the -cdrom option and its argument. This is to tell QEMU that we no longer want to boot from the ISO file that we downloaded, but from the installed android system. + +You should see the android booting menu now: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 49 android 8.1 oreo on linux][9] + +Then you’ll be taken to the first preparation wizard, choose your language and continue: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 51 android 8.1 oreo on linux][10] + +From here, choose the “Set up as new” option: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 53 android 8.1 oreo on linux][11] + +Then android will ask you about if you want to login to your current Google account. This step is optional, but important so that you can use the Play Store later: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 55 android 8.1 oreo on linux][12] + +Then you’ll need to accept the terms and conditions: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 57 android 8.1 oreo on linux][13] + +Now you can choose your current timezone: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 59 android 8.1 oreo on linux][14] + +The system will ask you now if you want to enable any data collection features. If I were you, I’d simply turn them all off like that: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 61 android 8.1 oreo on linux][15] + +Finally, you’ll have 2 launcher types to choose from, I recommend that you choose the Launcher3 option and make it the default: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 63 android 8.1 oreo on linux][16] + +Then you’ll see your fully-working android system home screen: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 65 android 8.1 oreo on linux][17] + +From here now, you can do all the tasks you want; You can use the built-in android apps, or you may browse the settings of your system to adjust it however you like. You may change look and feeling of your system, or you can run Chrome for example: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 67 android 8.1 oreo on linux][18] + +You may start installing some apps like WhatsApp and others from the Google Play store for your own use: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 69 android 8.1 oreo on linux][19] + +You can now do whatever you want with your system. Congratulations! + +### How to Easily Run Android 8.1 Oreo Later + +We don’t want to always have to open the terminal window and write that long QEMU command to run the android system, but we want to run it in just 1 click whenever we need that. + +To do this, we’ll create a new file under /usr/share/applications called android.desktop with the following command: + +``` +sudo nano /usr/share/applications/android.desktop +``` + +And paste the following contents inside it (Right click and then paste): + +``` +[Desktop Entry] +Name=Android 8.1 +Comment=Run Android 8.1 Oreo on Linux using QEMU +Icon=phone +Exec=bash -c 'pkexec env DISPLAY=$DISPLAY XAUTHORITY=$XAUTHORITY qemu-system-x86_64 -m 2048 -boot d -enable-kvm -smp 3 -net nic -net user -hda /home/mhsabbagh/android.img' +Terminal=false +Type=Application +StartupNotify=true +Categories=GTK; +``` + +Again, you have to replace /home/mhsabbagh/android.img with the path to the local image on your system. Then save the file (Ctrl + X, then press Y, then Enter). + +Notice that we needed to use “pkexec” to run QEMU with root privileges because starting from newer versions, accessing to the KVM technology via libvirt is not allowed for normal users; That’s why it will ask you for the root password each time. + +Now, you’ll see the android icon in the applications menu all the time, you can simply click it any time you want to use android and the QEMU program will start: + +![Install Android 8.1 Oreo on Linux To Run Apps & Games 71 android 8.1 oreo on linux][20] + +### Conclusion + +We showed you how install and run android 8.1 Oreo on your Linux system. From now on, it should be much easier on you to do your android-based tasks without some other software like Blutsticks and similar methods. Here, you have a fully-working and functional android system that you can manipulate however you like, and if anything goes wrong, you can simply nuke the image file and run the installation all over again any time you want. + +Have you tried android x86 before? How was your experience with it? + + +-------------------------------------------------------------------------------- + +via: https://fosspost.org/tutorials/install-android-8-1-oreo-on-linux + +作者：[Python Programmer;Open Source Software Enthusiast. Worked On Developing A Lot Of Free Software. The Founder Of Foss Post;Foss Project. Computer Science Major.][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.android-x86.org/ +[2]: http://www.android-x86.org/download +[3]: https://fosspost.org/tutorials/use-qemu-test-operating-systems-distributions +[4]: https://i0.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-16.png?resize=694%2C548&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 40 android 8.1 oreo on linux) +[5]: https://i0.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-15.png?resize=673%2C537&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 42 android 8.1 oreo on linux) +[6]: https://i1.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-14.png?resize=769%2C469&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 44 android 8.1 oreo on linux) +[7]: https://i1.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-13.png?resize=767%2C466&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 46 android 8.1 oreo on linux) +[8]: https://i0.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-12.png?resize=750%2C460&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 48 android 8.1 oreo on linux) +[9]: https://i1.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-11.png?resize=754%2C456&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 50 android 8.1 oreo on linux) +[10]: https://i0.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-10.png?resize=850%2C559&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 52 android 8.1 oreo on linux) +[11]: https://i0.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-09.png?resize=850%2C569&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 54 android 8.1 oreo on linux) +[12]: https://i1.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-08.png?resize=850%2C562&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 56 android 8.1 oreo on linux) +[13]: https://i2.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-07-1.png?resize=850%2C561&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 58 android 8.1 oreo on linux) +[14]: https://i0.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-06.png?resize=850%2C569&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 60 android 8.1 oreo on linux) +[15]: https://i1.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-05.png?resize=850%2C559&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 62 android 8.1 oreo on linux) +[16]: https://i1.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-04.png?resize=850%2C553&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 64 android 8.1 oreo on linux) +[17]: https://i0.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-03.png?resize=850%2C571&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 66 android 8.1 oreo on linux) +[18]: https://i1.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-02.png?resize=850%2C555&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 68 android 8.1 oreo on linux) +[19]: https://i2.wp.com/fosspost.org/wp-content/uploads/2019/02/Android-8.1-Oreo-on-Linux-01.png?resize=850%2C557&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 70 android 8.1 oreo on linux) +[20]: https://i0.wp.com/fosspost.org/wp-content/uploads/2019/02/Screenshot-at-2019-02-17-1539.png?resize=850%2C557&ssl=1 (Install Android 8.1 Oreo on Linux To Run Apps & Games 72 android 8.1 oreo on linux) diff --git a/sources/tech/20190218 Emoji-Log- A new way to write Git commit messages.md b/sources/tech/20190218 Emoji-Log- A new way to write Git commit messages.md new file mode 100644 index 0000000000..e821337a60 --- /dev/null +++ b/sources/tech/20190218 Emoji-Log- A new way to write Git commit messages.md @@ -0,0 +1,176 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Emoji-Log: A new way to write Git commit messages) +[#]: via: (https://opensource.com/article/19/2/emoji-log-git-commit-messages) +[#]: author: (Ahmad Awais https://opensource.com/users/mrahmadawais) + +Emoji-Log: A new way to write Git commit messages +====== +Add context to your commits with Emoji-Log. + + +I'm a full-time open source developer—or, as I like to call it, an 🎩 open sourcerer. I've been working with open source software for over a decade and [built hundreds][1] of open source software applications. + +I also am a big fan of the Don't Repeat Yourself (DRY) philosophy and believe writing better Git commit messages—ones that are contextual enough to serve as a changelog for your open source software—is an important component of DRY. One of the many workflows I've written is [Emoji-Log][2], a straightforward, open source Git commit log standard. It improves the developer experience (DX) by using emoji to create better Git commit messages. + +I've used Emoji-Log while building the [VSCode Tips & Tricks repo][3], my 🦄 [Shades of Purple VSCode theme repo][4], and even an [automatic changelog][5] that looks beautiful. + +### Emoji-Log's philosophy + +I like emoji (which is, in fact, the plural of emoji). I like 'em a lot. Programming, code, geeks/nerds, open source… all of that is inherently dull and sometimes boring. Emoji help me add colors and emotions to the mix. There's nothing wrong with wanting to attach feelings to the 2D, flat, text-based world of code. + +Instead of memorizing [hundreds of emoji][6], I've learned it's better to keep the categories small and general. Here's the philosophy that guides writing commit messages with Emoji-Log: + + 1. **Imperative** + * Make your Git commit messages imperative. + * Write commit message like you're giving an order. + * e.g., Use ✅ **Add** instead of ❌ **Added** + * e.g., Use ✅ **Create** instead of ❌ **Creating** + 2. **Rules** + * A small number of categories are easy to memorize. + * Nothing more, nothing less + * e.g. **📦 NEW** , **👌 IMPROVE** , **🐛 FIX** , **📖 DOC** , **🚀 RELEASE** , and **✅ TEST** + 3. **Actions** + * Make Git commits based on actions you take. + * Use a good editor like [VSCode][7] to commit the right files with commit messages. + + + +### Writing commit messages + +Use only the following Git commit messages. The simple and small footprint is the key to Emoji-Logo. + + 1. **📦 NEW: IMPERATIVE_MESSAGE** + * Use when you add something entirely new. + * e.g., **📦 NEW: Add Git ignore file** + 2. **👌 IMPROVE: IMPERATIVE_MESSAGE** + * Use when you improve/enhance piece of code like refactoring etc. + * e.g., **👌 IMPROVE: Remote IP API Function** + 3. **🐛 FIX: IMPERATIVE_MESSAGE** + * Use when you fix a bug. Need I say more? + * e.g., **🐛 FIX: Case converter** + 4. **📖 DOC: IMPERATIVE_MESSAGE** + * Use when you add documentation, like README.md or even inline docs. + * e.g., **📖 DOC: API Interface Tutorial** + 5. **🚀 RELEASE: IMPERATIVE_MESSAGE** + * Use when you release a new version. e.g., **🚀 RELEASE: Version 2.0.0** + 6. **✅ TEST: IMPERATIVE_MESSAGE** + * Use when you release a new version. + * e.g., **✅ TEST: Mock User Login/Logout** + + + +That's it for now. Nothing more, nothing less. + +### Emoji-Log functions + +For quick prototyping, I have made the following functions that you can add to your **.bashrc** / **.zshrc** files to use Emoji-Log quickly. + +``` +#.# Better Git Logs. + +### Using EMOJI-LOG (https://github.com/ahmadawais/Emoji-Log). + + + +# Git Commit, Add all and Push — in one step. + +function gcap() { + git add . && git commit -m "$*" && git push +} + +# NEW. +function gnew() { + gcap "📦 NEW: $@" +} + +# IMPROVE. +function gimp() { + gcap "👌 IMPROVE: $@" +} + +# FIX. +function gfix() { + gcap "🐛 FIX: $@" +} + +# RELEASE. +function grlz() { + gcap "🚀 RELEASE: $@" +} + +# DOC. +function gdoc() { + gcap "📖 DOC: $@" +} + +# TEST. +function gtst() { + gcap "✅ TEST: $@" +} +``` + +To install these functions for the [fish shell][8], run the following commands: + +``` +function gcap; git add .; and git commit -m "$argv"; and git push; end; +function gnew; gcap "📦 NEW: $argv"; end +function gimp; gcap "👌 IMPROVE: $argv"; end; +function gfix; gcap "🐛 FIX: $argv"; end; +function grlz; gcap "🚀 RELEASE: $argv"; end; +function gdoc; gcap "📖 DOC: $argv"; end; +function gtst; gcap "✅ TEST: $argv"; end; +funcsave gcap +funcsave gnew +funcsave gimp +funcsave gfix +funcsave grlz +funcsave gdoc +funcsave gtst +``` + +If you prefer, you can paste these aliases directly in your **~/.gitconfig** file: + +``` +# Git Commit, Add all and Push — in one step. +cap = "!f() { git add .; git commit -m \"$@\"; git push; }; f" + +# NEW. +new = "!f() { git cap \"📦 NEW: $@\"; }; f" +# IMPROVE. +imp = "!f() { git cap \"👌 IMPROVE: $@\"; }; f" +# FIX. +fix = "!f() { git cap \"🐛 FIX: $@\"; }; f" +# RELEASE. +rlz = "!f() { git cap \"🚀 RELEASE: $@\"; }; f" +# DOC. +doc = "!f() { git cap \"📖 DOC: $@\"; }; f" +# TEST. +tst = "!f() { git cap \"✅ TEST: $@\"; }; f" +``` + + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/2/emoji-log-git-commit-messages + +作者：[Ahmad Awais][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/mrahmadawais +[b]: https://github.com/lujun9972 +[1]: https://github.com/ahmadawais +[2]: https://github.com/ahmadawais/Emoji-Log/ +[3]: https://github.com/ahmadawais/VSCode-Tips-Tricks +[4]: https://github.com/ahmadawais/shades-of-purple-vscode/commits/master +[5]: https://github.com/ahmadawais/shades-of-purple-vscode/blob/master/CHANGELOG.md +[6]: https://gitmoji.carloscuesta.me/ +[7]: https://VSCode.pro +[8]: https://en.wikipedia.org/wiki/Friendly_interactive_shell diff --git a/sources/tech/20190218 How To Restore Sudo Privileges To A User.md b/sources/tech/20190218 How To Restore Sudo Privileges To A User.md new file mode 100644 index 0000000000..8e6f6db66f --- /dev/null +++ b/sources/tech/20190218 How To Restore Sudo Privileges To A User.md @@ -0,0 +1,194 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How To Restore Sudo Privileges To A User) +[#]: via: (https://www.ostechnix.com/how-to-restore-sudo-privileges-to-a-user/) +[#]: author: (SK https://www.ostechnix.com/author/sk/) + +How To Restore Sudo Privileges To A User +====== + + + +The other day I was testing how to [**add a regular user to sudo group and remove the given privileges**][1] to make him as a normal user again on Ubuntu. While testing, I removed my administrative user from the **‘sudo’ group**. As you already know, a user should be in sudo group to do any administrative tasks. But, I had only one super user and I already took out his sudo privileges. Whenever I run a command with sudo prefix, I encountered an error – “ **sk is not in the sudoers file. This incident will be reported** “. I can’t do any administrative tasks. I couldn’t switch to root user using ‘sudo su’ command. As you know already, root user is disabled by default in Ubuntu, so I can’t log in as root user either. Have you ever been in a situation like this? No worries! This brief tutorial explains how to restore sudo privileges to a user on Linux. I tested this on Ubuntu 18.04 system, but it might work on other Linux distributions as well. + +### Restore Sudo Privileges + +Boot your Linux system into recovery mode. + +To do so, restart your system and press and hold the **SHIFT** key while booting. You will see the grub boot menu. Choose **“Advanced options for Ubuntu”** from the boot menu list. + +![][3] + +In the next screen, choose **“recovery mode”** option and hit ENTER: + +![][4] + +Next, choose **“Drop to root shell prompt”** option and hit ENTER key: + +![][5] + +You’re now in recovery mode as root user. + +![][6] + +Type the following command to mount root (/) file system in read/write mode. + +``` +mount -o remount,rw / +``` + +Now, add the user that you removed from the sudo group. + +In my case, I am adding the user called ‘sk’ to the sudo group using the following command: + +``` +adduser sk sudo +``` + +![][7] + +Then, type **exit** to return back to the recovery menu. Select **Resume** to start your Ubuntu system. + +![][8] + +Press ENTER to continue to log-in normal mode: + +![][9] + +Now check if the sudo privileges have been restored. + +To do so, type the following command from the Terminal. + +``` +$ sudo -l -U sk +``` + +Sample output: + +``` +[sudo] password for sk: +Matching Defaults entries for sk on ubuntuserver: +env_reset, mail_badpass, +secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin + +User sk may run the following commands on ubuntuserver: +(ALL : ALL) ALL +``` + +As you see in the above message, the user sk can run all commands with sudo prefix. Congratulations! You have successfully restored the sudo privileges to the user. + +#### There are also other possibilities for causing broken sudo + +Please note that I actually did it on purpose. I removed myself from the sudo group and fixed the broken sudo privileges as described above. Don’t do this if you have only one sudo user. And, this method will work only on systems that you have physical access. If it is remote server or vps, it is very difficult to fix it. You might require your hosting provider’s help. + +Also, there are two other possibilities for causing broken sudo. + + * The /etc/sudoers file might have been altered. + * You or someone might have changed the permission of /etc/sudoers file. + + + +If you have done any one or all of the above mentioned things and ended up with broken sudo, try the following solutions. + +**Solution 1:** + +If you have altered the contents of /etc/sudoers file, go to the recovery mode as described earlier. + +Backup the existing /etc/sudoers file before making any changes. + +``` +cp /etc/sudoers /etc/sudoers.bak +``` + +Then, open /etc/sudoers file: + +``` +visudo +``` + +Make the changes in the file to look like this: + +``` +# +# This file MUST be edited with the 'visudo' command as root. +# +# Please consider adding local content in /etc/sudoers.d/ instead of +# directly modifying this file. +# +# See the man page for details on how to write a sudoers file. +# +Defaults env_reset +Defaults mail_badpass +Defaults secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin" + +# Host alias specification + +# User alias specification + +# Cmnd alias specification + +# User privilege specification +root ALL=(ALL:ALL) ALL + +# Members of the admin group may gain root privileges +%admin ALL=(ALL) ALL + +# Allow members of group sudo to execute any command +%sudo ALL=(ALL:ALL) ALL + +# See sudoers(5) for more information on "#include" directives: + +#includedir /etc/sudoers.d +``` + +Once you modified the contents to reflect like this, press **CTRL+X** and **y** save and close the file. + +Finally, type ‘exit’ and select **Resume** to start your Ubuntu system to exit from the recovery mode and continue booting as normal user. + +Now, try to use run any command with sudo prefix to verify if the sudo privileges are restored. + +**Solution 2:** + +If you changed the permission of the /etc/sudoers file, this method will fix the broken sudo issue. + +From the recovery mode, run the following command to set the correct permission to /etc/sudoers file: + +``` +chmod 0440 /etc/sudoers +``` + +Once you set the proper permission to the file, type ‘exit’ and select **Resume** to start your Ubuntu system in normal mode. Finally, verify if you can able to run any sudo command. + +**Suggested read:** + +And, that’s all for now. Hope this was useful . More good stuffs to come. Stay tuned! + +Cheers! + + + +-------------------------------------------------------------------------------- + +via: https://www.ostechnix.com/how-to-restore-sudo-privileges-to-a-user/ + +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/how-to-grant-and-remove-sudo-privileges-to-users-on-ubuntu/ +[2]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[3]: http://www.ostechnix.com/wp-content/uploads/2019/02/fix-broken-sudo-1.png +[4]: http://www.ostechnix.com/wp-content/uploads/2019/02/fix-broken-sudo-2.png +[5]: http://www.ostechnix.com/wp-content/uploads/2019/02/fix-broken-sudo-3.png +[6]: http://www.ostechnix.com/wp-content/uploads/2019/02/fix-broken-sudo-4.png +[7]: http://www.ostechnix.com/wp-content/uploads/2019/02/fix-broken-sudo-5-1.png +[8]: http://www.ostechnix.com/wp-content/uploads/2019/02/fix-broken-sudo-6.png +[9]: http://www.ostechnix.com/wp-content/uploads/2019/02/fix-broken-sudo-7.png diff --git a/sources/tech/20190218 SPEED TEST- x86 vs. ARM for Web Crawling in Python.md b/sources/tech/20190218 SPEED TEST- x86 vs. ARM for Web Crawling in Python.md new file mode 100644 index 0000000000..86b5230d2d --- /dev/null +++ b/sources/tech/20190218 SPEED TEST- x86 vs. ARM for Web Crawling in Python.md @@ -0,0 +1,533 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (SPEED TEST: x86 vs. ARM for Web Crawling in Python) +[#]: via: (https://blog.dxmtechsupport.com.au/speed-test-x86-vs-arm-for-web-crawling-in-python/) +[#]: author: (James Mawson https://blog.dxmtechsupport.com.au/author/james-mawson/) + +SPEED TEST: x86 vs. ARM for Web Crawling in Python +====== + +![][1] + +Can you imagine if your job was to trawl competitor websites and jot prices down by hand, again and again and again? You’d burn your whole office down by lunchtime. + +So, little wonder web crawlers are huge these days. They can keep track of customer sentiment and trending topics, monitor job openings, real estate transactions, UFC results, all sorts of stuff. + +For those of a certain bent, this is fascinating stuff. Which is how I found myself playing around with [Scrapy][2], an open source web crawling framework written in Python. + +Being wary of the potential to do something catastrophic to my computer while poking with things I didn’t understand, I decided to install it on my main machine but a Raspberry Pi. + +And wouldn’t you know it? It actually didn’t run too shabby on the little tacker. Maybe this is a good use case for an ARM server? + +Google had no solid answer. The nearest thing I found was [this Drupal hosting drag race][3], which showed an ARM server outperforming a much more expensive x86 based account. + +That was definitely interesting. I mean, isn’t a web server kind of like a crawler in reverse? But with one operating on a LAMP stack and the other on a Python interpreter, it’s hardly the exact same thing. + +So what could I do? Only one thing. Get some VPS accounts and make them race each other. + +### What’s the Deal With ARM Processors? + +ARM is now the most popular CPU architecture in the world. + +But it’s generally seen as something you’d opt for to save money and battery life, rather than a serious workhorse. + +It wasn’t always that way: this CPU was designed in Cambridge, England to power the fiendishly expensive [Acorn Archimedes][4]. This was the most powerful desktop computer in the world, and by a long way too: it was multiple times the speed of the fastest 386. + +Acorn, like Commodore and Atari, somewhat ignorantly believed that the making of a great computer company was in the making of great computers. Bill Gates had a better idea. He got DOS on as many x86 machines – of the most widely varying quality and expense – as he could. + +Having the best user base made you the obvious platform for third party developers to write software for; having all the software support made yours the most useful computer. + +Even Apple nearly bit the dust. All the $$$$ were in building a better x86 chip, this was the architecture that ended up being developed for serious computing. + +That wasn’t the end for ARM though. Their chips weren’t just fast, they could run well without drawing much power or emitting much heat. That made them a preferred technology in set top boxes, PDAs, digital cameras, MP3 players, and basically anything that either used a battery or where you’d just rather avoid the noise of a large fan. + +So it was that Acorn spun off ARM, who began an idiosyncratic business model that continues to today: ARM doesn’t actually manufacture any chips, they license their intellectual property to others who do. + +Which is more or less how they ended up in so many phones and tablets. When Linux was ported to the architecture, the door opened to other open source technologies, which is how we can run a web crawler on these chips today. + +#### ARM in the Server Room + +Some big names, like [Microsoft][5] and [Cloudflare][6], have placed heavy bets on the British Bulldog for their infrastructure. But for those of us with more modest budgets, the options are fairly sparse. + +In fact, when it comes to cheap and cheerful VPS accounts that you can stick on the credit card for a few bucks a month, for years the only option was [Scaleway][7]. + +This changed a few months ago when public cloud heavyweight [AWS][8] launched its own ARM processor: the [AWS Graviton][9]. + +I decided to grab one of each, and race them against the most similar Intel offering from the same provider. + +### Looking Under the Hood + +So what are we actually racing here? Let’s jump right in. + +#### Scaleway + +Scaleway positions itself as “designed for developers”. And you know what? I think that’s fair enough: it’s definitely been a good little sandbox for developing and prototyping. + +The dirt simple product offering and clean, easy dashboard guides you from home page to bash shell in minutes. That makes it a strong option for small businesses, freelancers and consultants who just want to get straight into a good VPS at a great price to run some crawls. + +The ARM account we will be using is their [ARM64-2GB][10], which costs 3 euros a month and has 4 Cavium ThunderX cores. This launched in 2014 as the first server-class ARMv8 processor, but is now looking a bit middle-aged, having been superseded by the younger, prettier ThunderX2. + +The x86 account we will be comparing it to is the [1-S][11], which costs a more princely 4 euros a month and has 2 Intel Atom C3995 cores. Intel’s Atom range is a low power single-threaded system on chip design, first built for laptops and then adapted for server use. + +These accounts are otherwise fairly similar: they each have 2 gigabytes of memory, 50 gigabytes of SSD storage and 200 Mbit/s bandwidth. The disk drives possibly differ, but with the crawls we’re going to run here, this won’t come into play, we’re going to be doing everything in memory. + +When I can’t use a package manager I’m familiar with, I become angry and confused, a bit like an autistic toddler without his security blanket, entirely beyond reasoning or consolation, it’s quite horrendous really, so both of these accounts will use Debian Stretch. + +#### Amazon Web Services + +In the same length of time as it takes you to give Scaleway your credit card details, launch a VPS, add a sudo user and start installing dependencies, you won’t even have gotten as far as registering your AWS account. You’ll still be reading through the product pages trying to figure out what’s going on. + +There’s a serious breadth and depth here aimed at enterprises and others with complicated or specialised needs. + +The AWS Graviton we wanna drag race is part of AWS’s “Elastic Compute Cloud” or EC2 range. I’ll be running it as an on-demand instance, which is the most convenient and expensive way to use EC2. AWS also operates a [spot market][12], where you get the server much cheaper if you can be flexible about when it runs. There’s also a [mid-priced option][13] if you want to run it 24/7. + +Did I mention that AWS is complicated? Anyhoo.. + +The two accounts we’re comparing are [a1.medium][14] and [t2.small][15]. They both offer 2GB of RAM. Which begs the question: WTF is a vCPU? Confusingly, it’s a different thing on each account. + +On the a1.medium account, a vCPU is a single core of the new AWS Graviton chip. This was built by Annapurna Labs, an Israeli chip maker bought by Amazon in 2015. This is a single-threaded 64-bit ARMv8 core exclusive to AWS. This has an on-demand price of 0.0255 US dollars per hour. + +Our t2.small account runs on an Intel Xeon – though exactly which Xeon chip it is, I couldn’t really figure out. This has two threads per core – though we’re not really getting the whole core, or even the whole thread. + +Instead we’re getting a “baseline performance of 20%, with the ability to burst above that baseline using CPU credits”. Which makes sense in principle, though it’s completely unclear to me what to actually expect from this. The on-demand price for this account is 0.023 US dollars per hour. + +I couldn’t find Debian in the image library here, so both of these accounts will run Ubuntu 18.04. + +### Beavis and Butthead Do Moz’s Top 500 + +To test these VPS accounts, I need a crawler to run – one that will let the CPU stretch its legs a bit. One way to do this would be to just hammer a few websites with as many requests as fast as possible, but that’s not very polite. What we’ll do instead is a broad crawl of many websites at once. + +So it’s in tribute to my favourite physicist turned filmmaker, Mike Judge, that I wrote beavis.py. This crawls Moz’s Top 500 Websites to a depth of 3 pages to count how many times the words “wood” and “ass” occur anywhere within the HTML source. + +Not all 500 websites will actually get crawled here – some will be excluded by robots.txt and others will require javascript to follow links and so on. But it’s a wide enough crawl to keep the CPU busy. + +Python’s [global interpreter lock][16] means that beavis.py can only make use of a single CPU thread. To test multi-threaded we’re going to have to launch multiple spiders as seperate processes. + +This is why I wrote butthead.py. Any true fan of the show knows that, as crude as Butthead was, he was always slightly more sophisticated than Beavis. + +Splitting the crawl into multiple lists of start pages and allowed domains might slightly impact what gets crawled – fewer external links to other websites in the top 500 will get followed. But every crawl will be different anyway, so we will count how many pages are scraped as well as how long they take. + +### Installing Scrapy on an ARM Server + +Installing Scrapy is basically the same on each architecture. You install pip and various other dependencies, then install Scrapy from pip. + +Installing Scrapy from pip to an ARM device does take noticeably longer though. I’m guessing this is because it has to compile the binary parts from source. + +Once Scrapy is installed, I ran it from the shell to check that it’s fetching pages. + +On Scaleway’s ARM account, there seemed to be a hitch with the service_identity module: it was installed but not working. This issue had come up on the Raspberry Pi as well, but not the AWS Graviton. + +Not to worry, this was easily fixed with the following command: + +``` +sudo pip3 install service_identity --force --upgrade +``` + +Then we were off and racing! + +### Single Threaded Crawls + +The Scrapy docs say to try to [keep your crawls running between 80-90% CPU usage][17]. In practice, it’s hard – at least it is with the script I’ve written. What tends to happen is that the CPU gets very busy early in the crawl, drops a little bit and then rallies again. + +The last part of the crawl, where most of the domains have been finished, can go on for quite a few minutes, which is frustrating, because at that point it feels like more a measure of how big the last website is than anything to do with the processor. + +So please take this for what it is: not a state of the art benchmarking tool, but a short and slightly balding Australian in his underpants running some scripts and watching what happens. + +So let’s get down to brass tacks. We’ll start with the Scaleway crawls. + +| VPS | Account | Time | Pages | Scraped | Pages/Hour | €/million | pages | +| --------- | ------- | ------- | ------ | ---------- | ---------- | --------- | ----- | +| Scaleway | | | | | | | | +| ARM64-2GB | 108m | 59.27s | 38,205 | 21,032.623 | 0.28527 | | | +| --------- | ------- | ------- | ------ | ---------- | ---------- | --------- | ----- | +| Scaleway | | | | | | | | +| 1-S | 97m | 44.067s | 39,476 | 24,324.648 | 0.33011 | | | + +I kept an eye on the CPU use of both of these crawls using [top][18]. Both crawls hit 100% CPU use at the beginning, but the ThunderX chip was definitely redlining a lot more. That means these figures understate how much faster the Atom core crawls than the ThunderX. + +While I was watching CPU use in top, I could also see how much RAM was in use – this increased as the crawl continued. The ARM account used 14.7% at the end of the crawl, while the x86 was at 15%. + +Watching the logs of these crawls, I also noticed a lot more pages timing out and going missing when the processor was maxed out. That makes sense – if the CPU’s too busy to respond to everything then something’s gonna go missing. + +That’s not such a big deal when you’re just racing the things to see which is fastest. But in a real-world situation, with business outcomes at stake in the quality of your data, it’s probably worth having a little bit of headroom. + +And what about AWS? + +| VPS Account | Time | Pages Scraped | Pages / Hour | $ / Million Pages | +| ----------- | ---- | ------------- | ------------ | ----------------- | +| a1.medium | 100m 39.900s | 41,294 | 24,612.725 | 1.03605 | +| t2.small | 78m 53.171s | 41,200 | 31,336.286 | 0.73397 | + +I’ve included these results for sake of comparison with the Scaleway crawls, but these crawls were kind of a bust. Monitoring the CPU use – this time through the AWS dashboard rather than through top – showed that the script wasn’t making good use of the available processing power on either account. + +This was clearest with the a1.medium account – it hardly even got out of bed. It peaked at about 45% near the beginning and then bounced around between 20% and 30% for the rest. + +What’s intriguing to me about this is that the exact same script ran much slower on the ARM processor – and that’s not because it hit a limit of the Graviton’s CPU power. It had oodles of headroom left. Even the Intel Atom core managed to finish, and that was maxing out for some of the crawl. The settings were the same in the code, the way they were being handled differently on the different architecture. + +It’s a bit of a black box to me whether that’s something inherent to the processor itself, the way the binaries were compiled, or some interaction between the two. I’m going to speculate that we might have seen the same thing on the Scaleway ARM VPS, if we hadn’t hit the limit of the CPU core’s processing power first. + +It was harder to know how the t2.small account was doing. The crawl sat at about 20%, sometimes going as high as 35%. Was that it meant by “baseline performance of 20%, with the ability to burst to a higher level”? I had no idea. But I could see on the dashboard I wasn’t burning through any CPU credits. + +Just to make extra sure, I installed [stress][19] and ran it for a few minutes; sure enough, this thing could do 100% if you pushed it. + +Clearly, I was going to need to crank the settings up on both these processors to make them sweat a bit, so I set CONCURRENT_REQUESTS to 5000 and REACTOR_THREADPOOL_MAXSIZE to 120 and ran some more crawls. + +| VPS Account | Time | Pages Scraped | Pages/hr | $/10000 Pages | +| ----------- | ---- | ------------- | -------- | ------------- | +| a1.medium | 46m 13.619s | 40,283 | 52,285.047 | 0.48771 | +| t2.small | 41m7.619s | 36,241 | 52,871.857 | 0.43501 | +| t2.small (No CPU credits) | 73m 8.133s | 34,298 | 28,137.8891 | 0.81740 | + +The a1 instance hit 100% usage about 5 minutes into the crawl, before dropping back to 80% use for another 20 minutes, climbing up to 96% again and then dropping down again as it was wrapping things up. That was probably about as well-tuned as I was going to get it. + +The t2 instance hit 50% early in the crawl and stayed there for until it was nearly done. With 2 threads per core, 50% CPU use is one thread maxed out. + +Here we see both accounts produce similar speeds. But the Xeon thread was redlining for most of the crawl, and the Graviton was not. I’m going to chalk this up as a slight win for the Graviton. + +But what about once you’ve burnt through all your CPU credits? That’s probably the fairer comparison – to only use them as you earn them. I wanted to test that as well. So I ran stress until all the CPU credits were exhausted and ran the crawl again. + +With no credits in the bank, the CPU usage maxed out at 27% and stayed there. So many pages ended up going missing that it actually performed worse than when on the lower settings. + +### Multi Threaded Crawls + +Dividing our crawl up between multiple spiders in separate processes offers a few more options to make use of the available cores. + +I first tried dividing everything up between 10 processes and launching them all at once. This turned out to be slower than just dividing them up into 1 process per core. + +I got the best result by combining these methods – dividing the crawl up into 10 processes and then launching 1 process per core at the start and then the rest as these crawls began to wind down. + +To make this even better, you could try to minimise the problem of the last lingering crawler by making sure the longest crawls start first. I actually attempted to do this. + +Figuring that the number of links on the home page might be a rough proxy for how large the crawl would be, I built a second spider to count them and then sort them in descending order of number of outgoing links. This preprocessing worked well and added a little over a minute. + +It turned out though that blew the crawling time out beyond two hours! Putting all the most link heavy websites together in the same process wasn’t a great idea after all. + +You might effectively deal with this by tweaking the number of domains per process as well – or by shuffling the list after it’s ordered. That’s a bit much for Beavis and Butthead though. + +So I went back to my earlier method that had worked somewhat well: + +| VPS Account | Time | Pages Scraped | Pages/hr | €/10,000 pages | +| ----------- | ---- | ------------- | -------- | -------------- | +| Scaleway ARM64-2GB | 62m 10.078s | 36,158 | 34,897.0719 | 0.17193 | +| Scaleway 1-S | 60m 56.902s | 36,725 | 36,153.5529 | 0.22128 | + +After all that, using more cores did speed up the crawl. But it’s hardly a matter of just halving or quartering the time taken. + +I’m certain that a more experienced coder could better optimise this to take advantage of all the cores. But, as far as “out of the box” Scrapy performance goes, it seems to be a lot easier to speed up a crawl by using faster threads rather than by throwing more cores at it. + +As it is, the Atom has scraped slightly more pages in slightly less time. On a value for money metric, you could possibly say that the ThunderX is ahead. Either way, there’s not a lot of difference here. + +### Everything You Always Wanted to Know About Ass and Wood (But Were Afraid to Ask) + +After scraping 38,205 pages, our crawler found 24,170,435 mentions of ass and 54,368 mentions of wood. + +![][20] + +Considered on its own, this is a respectable amount of wood. + +But when you set it against the sheer quantity of ass we’re dealing with here, the wood looks miniscule. + +### The Verdict + +From what’s visible to me at the moment, it looks like the CPU architecture you use is actually less important than how old the processor is. The AWS Graviton from 2018 was the winner here in single-threaded performance. + +You could of course argue that the Xeon still wins, core for core. But then you’re not really going dollar for dollar anymore, or even thread for thread. + +The Atom from 2017, on the other hand, comfortably bested the ThunderX from 2014. Though, on the value for money metric, the ThunderX might be the clear winner. Then again, if you can run your crawls on Amazon’s spot market, the Graviton is still ahead. + +All in all, I think this shows that, yes, you can crawl the web with an ARM device, and it can compete on both performance and price. + +Whether the difference is significant enough for you to turn what you’re doing upside down is a whole other question of course. Certainly, if you’re already on the AWS cloud – and your code is portable enough – then it might be worthwhile testing out their a1 instances. + +Hopefully we will see more ARM options on the public cloud in near future. + +### The Scripts + +This is my first real go at doing anything in either Python or Scrapy. So this might not be great code to learn from. Some of what I’ve done here – such as using global variables – is definitely a bit kludgey. + +Still, I want to be transparent about my methods, so here are my scripts. + +To run them, you’ll need Scrapy installed and you will need the CSV file of [Moz’s top 500 domains][21]. To run butthead.py you will also need [psutil][22]. + +##### beavis.py + +``` +import scrapy +from scrapy.spiders import CrawlSpider, Rule +from scrapy.linkextractors import LinkExtractor +from scrapy.crawler import CrawlerProcess + +ass = 0 +wood = 0 +totalpages = 0 + +def getdomains(): + + moz500file = open('top500.domains.05.18.csv') + + domains = [] + moz500csv = moz500file.readlines() + + del moz500csv[0] + + for csvline in moz500csv: + leftquote = csvline.find('"') + rightquote = leftquote + csvline[leftquote + 1:].find('"') + domains.append(csvline[leftquote + 1:rightquote]) + + return domains + +def getstartpages(domains): + + startpages = [] + + for domain in domains: + startpages.append('http://' + domain) + + return startpages + +class AssWoodItem(scrapy.Item): + ass = scrapy.Field() + wood = scrapy.Field() + url = scrapy.Field() + +class AssWoodPipeline(object): + def __init__(self): + self.asswoodstats = [] + + def process_item(self, item, spider): + self.asswoodstats.append((item.get('url'), item.get('ass'), item.get('wood'))) + + def close_spider(self, spider): + asstally, woodtally = 0, 0 + + for asswoodcount in self.asswoodstats: + asstally += asswoodcount[1] + woodtally += asswoodcount[2] + + global ass, wood, totalpages + ass = asstally + wood = woodtally + totalpages = len(self.asswoodstats) + +class BeavisSpider(CrawlSpider): + name = "Beavis" + allowed_domains = getdomains() + start_urls = getstartpages(allowed_domains) + #start_urls = [ 'http://medium.com' ] + custom_settings = { + 'DEPTH_LIMIT': 3, + 'DOWNLOAD_DELAY': 3, + 'CONCURRENT_REQUESTS': 1500, + 'REACTOR_THREADPOOL_MAXSIZE': 60, + 'ITEM_PIPELINES': { '__main__.AssWoodPipeline': 10 }, + 'LOG_LEVEL': 'INFO', + 'RETRY_ENABLED': False, + 'DOWNLOAD_TIMEOUT': 30, + 'COOKIES_ENABLED': False, + 'AJAXCRAWL_ENABLED': True + } + + rules = ( Rule(LinkExtractor(), callback='parse_asswood'), ) + + def parse_asswood(self, response): + if isinstance(response, scrapy.http.TextResponse): + item = AssWoodItem() + item['ass'] = response.text.casefold().count('ass') + item['wood'] = response.text.casefold().count('wood') + item['url'] = response.url + yield item + + +if __name__ == '__main__': + + process = CrawlerProcess({ + 'USER_AGENT': 'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)' + }) + + process.crawl(BeavisSpider) + process.start() + + print('Uhh, that was, like, ' + str(totalpages) + ' pages crawled.') + print('Uh huhuhuhuh. It said ass ' + str(ass) + ' times.') + print('Uh huhuhuhuh. It said wood ' + str(wood) + ' times.') +``` + +##### butthead.py + +``` +import scrapy, time, psutil +from scrapy.spiders import CrawlSpider, Rule, Spider +from scrapy.linkextractors import LinkExtractor +from scrapy.crawler import CrawlerProcess +from multiprocessing import Process, Queue, cpu_count + +ass = 0 +wood = 0 +totalpages = 0 +linkcounttuples =[] + +def getdomains(): + + moz500file = open('top500.domains.05.18.csv') + + domains = [] + moz500csv = moz500file.readlines() + + del moz500csv[0] + + for csvline in moz500csv: + leftquote = csvline.find('"') + rightquote = leftquote + csvline[leftquote + 1:].find('"') + domains.append(csvline[leftquote + 1:rightquote]) + + return domains + +def getstartpages(domains): + + startpages = [] + + for domain in domains: + startpages.append('http://' + domain) + + return startpages + +class AssWoodItem(scrapy.Item): + ass = scrapy.Field() + wood = scrapy.Field() + url = scrapy.Field() + +class AssWoodPipeline(object): + def __init__(self): + self.asswoodstats = [] + + def process_item(self, item, spider): + self.asswoodstats.append((item.get('url'), item.get('ass'), item.get('wood'))) + + def close_spider(self, spider): + asstally, woodtally = 0, 0 + + for asswoodcount in self.asswoodstats: + asstally += asswoodcount[1] + woodtally += asswoodcount[2] + + global ass, wood, totalpages + ass = asstally + wood = woodtally + totalpages = len(self.asswoodstats) + + +class ButtheadSpider(CrawlSpider): + name = "Butthead" + custom_settings = { + 'DEPTH_LIMIT': 3, + 'DOWNLOAD_DELAY': 3, + 'CONCURRENT_REQUESTS': 250, + 'REACTOR_THREADPOOL_MAXSIZE': 30, + 'ITEM_PIPELINES': { '__main__.AssWoodPipeline': 10 }, + 'LOG_LEVEL': 'INFO', + 'RETRY_ENABLED': False, + 'DOWNLOAD_TIMEOUT': 30, + 'COOKIES_ENABLED': False, + 'AJAXCRAWL_ENABLED': True + } + + rules = ( Rule(LinkExtractor(), callback='parse_asswood'), ) + + + def parse_asswood(self, response): + if isinstance(response, scrapy.http.TextResponse): + item = AssWoodItem() + item['ass'] = response.text.casefold().count('ass') + item['wood'] = response.text.casefold().count('wood') + item['url'] = response.url + yield item + +def startButthead(domainslist, urlslist, asswoodqueue): + crawlprocess = CrawlerProcess({ + 'USER_AGENT': 'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)' + }) + + crawlprocess.crawl(ButtheadSpider, allowed_domains = domainslist, start_urls = urlslist) + crawlprocess.start() + asswoodqueue.put( (ass, wood, totalpages) ) + + +if __name__ == '__main__': + asswoodqueue = Queue() + domains=getdomains() + startpages=getstartpages(domains) + processlist =[] + cores = cpu_count() + + for i in range(10): + domainsublist = domains[i * 50:(i + 1) * 50] + pagesublist = startpages[i * 50:(i + 1) * 50] + p = Process(target = startButthead, args = (domainsublist, pagesublist, asswoodqueue)) + processlist.append(p) + + for i in range(cores): + processlist[i].start() + + time.sleep(180) + + i = cores + + while i != 10: + time.sleep(60) + if psutil.cpu_percent() < 66.7: + processlist[i].start() + i += 1 + + for i in range(10): + processlist[i].join() + + for i in range(10): + asswoodtuple = asswoodqueue.get() + ass += asswoodtuple[0] + wood += asswoodtuple[1] + totalpages += asswoodtuple[2] + + print('Uhh, that was, like, ' + str(totalpages) + ' pages crawled.') + print('Uh huhuhuhuh. It said ass ' + str(ass) + ' times.') + print('Uh huhuhuhuh. It said wood ' + str(wood) + ' times.') +``` + +-------------------------------------------------------------------------------- + +via: https://blog.dxmtechsupport.com.au/speed-test-x86-vs-arm-for-web-crawling-in-python/ + +作者：[James Mawson][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.dxmtechsupport.com.au/author/james-mawson/ +[b]: https://github.com/lujun9972 +[1]: https://blog.dxmtechsupport.com.au/wp-content/uploads/2019/02/quadbike-1024x683.jpg +[2]: https://scrapy.org/ +[3]: https://www.info2007.net/blog/2018/review-scaleway-arm-based-cloud-server.html +[4]: https://blog.dxmtechsupport.com.au/playing-badass-acorn-archimedes-games-on-a-raspberry-pi/ +[5]: https://www.computerworld.com/article/3178544/microsoft-windows/microsoft-and-arm-look-to-topple-intel-in-servers.html +[6]: https://www.datacenterknowledge.com/design/cloudflare-bets-arm-servers-it-expands-its-data-center-network +[7]: https://www.scaleway.com/ +[8]: https://aws.amazon.com/ +[9]: https://www.theregister.co.uk/2018/11/27/amazon_aws_graviton_specs/ +[10]: https://www.scaleway.com/virtual-cloud-servers/#anchor_arm +[11]: https://www.scaleway.com/virtual-cloud-servers/#anchor_starter +[12]: https://aws.amazon.com/ec2/spot/pricing/ +[13]: https://aws.amazon.com/ec2/pricing/reserved-instances/ +[14]: https://aws.amazon.com/ec2/instance-types/a1/ +[15]: https://aws.amazon.com/ec2/instance-types/t2/ +[16]: https://wiki.python.org/moin/GlobalInterpreterLock +[17]: https://docs.scrapy.org/en/latest/topics/broad-crawls.html +[18]: https://linux.die.net/man/1/top +[19]: https://linux.die.net/man/1/stress +[20]: https://blog.dxmtechsupport.com.au/wp-content/uploads/2019/02/Screenshot-from-2019-02-16-17-01-08.png +[21]: https://moz.com/top500 +[22]: https://pypi.org/project/psutil/ diff --git a/sources/tech/20190219 5 Good Open Source Speech Recognition-Speech-to-Text Systems.md b/sources/tech/20190219 5 Good Open Source Speech Recognition-Speech-to-Text Systems.md new file mode 100644 index 0000000000..c7609f5022 --- /dev/null +++ b/sources/tech/20190219 5 Good Open Source Speech Recognition-Speech-to-Text Systems.md @@ -0,0 +1,131 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (5 Good Open Source Speech Recognition/Speech-to-Text Systems) +[#]: via: (https://fosspost.org/lists/open-source-speech-recognition-speech-to-text) +[#]: author: (Simon James https://fosspost.org/author/simonjames) + +5 Good Open Source Speech Recognition/Speech-to-Text Systems +====== + + + +A speech-to-text (STT) system is as its name implies; A way of transforming the spoken words via sound into textual files that can be used later for any purpose. + +Speech-to-text technology is extremely useful. It can be used for a lot of applications such as a automation of transcription, writing books/texts using your own sound only, enabling complicated analyses on information using the generated textual files and a lot of other things. + +In the past, the speech-to-text technology was dominated by proprietary software and libraries; Open source alternatives didn’t exist or existed with extreme limitations and no community around. This is changing, today there are a lot of open source speech-to-text tools and libraries that you can use right now. + +Here we list 5 of them. + +### Open Source Speech Recognition Libraries + +#### Project DeepSpeech + +![5 Good Open Source Speech Recognition/Speech-to-Text Systems 15 open source speech recognition][1] + +This project is made by Mozilla; The organization behind the Firefox browser. It’s a 100% free and open source speech-to-text library that also implies the machine learning technology using TensorFlow framework to fulfill its mission. + +In other words, you can use it to build training models yourself to enhance the underlying speech-to-text technology and get better results, or even to bring it to other languages if you want. You can also easily integrate it to your other machine learning projects that you are having on TensorFlow. Sadly it sounds like the project is currently only supporting English by default. + +It’s also available in many languages such as Python (3.6); Which allows you to have it working in seconds: + +``` +pip3 install deepspeech +deepspeech --model models/output_graph.pbmm --alphabet models/alphabet.txt --lm models/lm.binary --trie models/trie --audio my_audio_file.wav +``` + +You can also install it using npm: + +``` +npm install deepspeech +``` + +For more information, refer to the [project’s homepage][2]. + +#### Kaldi + +![5 Good Open Source Speech Recognition/Speech-to-Text Systems 17 open source speech recognition][3] + +Kaldi is an open source speech recognition software written in C++, and is released under the Apache public license. It works on Windows, macOS and Linux. Its development started back in 2009. + +Kaldi’s main features over some other speech recognition software is that it’s extendable and modular; The community is providing tons of 3rd-party modules that you can use for your tasks. Kaldi also supports deep neural networks, and offers an [excellent documentation on its website][4]. + +While the code is mainly written in C++, it’s “wrapped” by Bash and Python scripts. So if you are looking just for the basic usage of converting speech to text, then you’ll find it easy to accomplish that via either Python or Bash. + +[Project’s homepage][5]. + +#### Julius + +![5 Good Open Source Speech Recognition/Speech-to-Text Systems 19 open source speech recognition][6] + +Probably one of the oldest speech recognition software ever; It’s development started in 1991 at the University of Kyoto, and then its ownership was transferred to an independent project team in 2005. + +Julius main features include its ability to perform real-time STT processes, low memory usage (Less than 64MB for 20000 words), ability to produce N-best/Word-graph output, ability to work as a server unit and a lot more. This software was mainly built for academic and research purposes. It is written in C, and works on Linux, Windows, macOS and even Android (on smartphones). + +Currently it supports both English and Japanese languages only. The software is probably availbale to install easily in your Linux distribution’s repository; Just search for julius package in your package manager. The latest version was [released][7] around one and half months ago. + +[Project’s homepage][8]. + +#### Wav2Letter++ + +![5 Good Open Source Speech Recognition/Speech-to-Text Systems 21 open source speech recognition][9] + +If you are looking for something modern, then this one is for you. Wav2Letter++ is an open source speech recognition software that was released by Facebook’s AI Research Team just 2 months ago. The code is released under the BSD license. + +Facebook is [describing][10] its library as “the fastest state-of-the-art speech recognition system available”. The concepts on which this tool is built makes it optimized for performance by default; Facebook’s also-new machine learning library [FlashLight][11] is used as the underlying core of Wav2Letter++. + +Wav2Letter++ needs you first to build a training model for the language you desire by yourself in order to train the algorithms on it. No pre-built support of any language (including English) is available; It’s just a machine-learning-driven tool to convert speech to text. It was written in C++, hence the name (Wav2Letter++). + +[Project’s homepage][12]. + +#### DeepSpeech2 + +![5 Good Open Source Speech Recognition/Speech-to-Text Systems 23 open source speech recognition][13] + +Researchers at the Chinese giant Baidu are also working on their own speech-to-text engine, called DeepSpeech2. It’s an end-to-end open source engine that uses the “PaddlePaddle” deep learning framework for converting both English & Mandarin Chinese languages speeches into text. The code is released under BSD license. + +The engine can be trained on any model and for any language you desire. The models are not released with the code; You’ll have to build them yourself, just like the other software. DeepSpeech2’s source code is written in Python; So it should be easy for you to get familiar with it if that’s the language you use. + +[Project’s homepage][14]. + +### Conclusion + +The speech recognition category is still mainly dominated by proprietary software giants like Google and IBM (which do provide their own closed-source commercial services for this), but the open source alternatives are promising. Those 5 open source speech recognition engines should get you going in building your application, all of them are still under heavy development by time. In few years, we expect open source to become the norm for those technologies just like in the other industries. + +If you have any other recommendations for this list, or comments in general, we’d love to hear them below! + +** + +Shares + + +-------------------------------------------------------------------------------- + +via: https://fosspost.org/lists/open-source-speech-recognition-speech-to-text + +作者：[Simon James][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://fosspost.org/author/simonjames +[b]: https://github.com/lujun9972 +[1]: https://i0.wp.com/fosspost.org/wp-content/uploads/2019/02/hero_speech-machine-learning2.png?resize=820%2C280&ssl=1 (5 Good Open Source Speech Recognition/Speech-to-Text Systems 16 open source speech recognition) +[2]: https://github.com/mozilla/DeepSpeech +[3]: https://i0.wp.com/fosspost.org/wp-content/uploads/2019/02/Screenshot-at-2019-02-19-1134.png?resize=591%2C138&ssl=1 (5 Good Open Source Speech Recognition/Speech-to-Text Systems 18 open source speech recognition) +[4]: http://kaldi-asr.org/doc/index.html +[5]: http://kaldi-asr.org +[6]: https://i2.wp.com/fosspost.org/wp-content/uploads/2019/02/mic_web.png?resize=385%2C100&ssl=1 (5 Good Open Source Speech Recognition/Speech-to-Text Systems 20 open source speech recognition) +[7]: https://github.com/julius-speech/julius/releases +[8]: https://github.com/julius-speech/julius +[9]: https://i2.wp.com/fosspost.org/wp-content/uploads/2019/02/fully_convolutional_ASR.png?resize=850%2C177&ssl=1 (5 Good Open Source Speech Recognition/Speech-to-Text Systems 22 open source speech recognition) +[10]: https://code.fb.com/ai-research/wav2letter/ +[11]: https://github.com/facebookresearch/flashlight +[12]: https://github.com/facebookresearch/wav2letter +[13]: https://i2.wp.com/fosspost.org/wp-content/uploads/2019/02/ds2.png?resize=850%2C313&ssl=1 (5 Good Open Source Speech Recognition/Speech-to-Text Systems 24 open source speech recognition) +[14]: https://github.com/PaddlePaddle/DeepSpeech diff --git a/sources/tech/20190220 Automation evolution.md b/sources/tech/20190220 Automation evolution.md new file mode 100644 index 0000000000..09167521c6 --- /dev/null +++ b/sources/tech/20190220 Automation evolution.md @@ -0,0 +1,81 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Automation evolution) +[#]: via: (https://leancrew.com/all-this/2019/02/automation-evolution/) +[#]: author: (Dr.Drang https://leancrew.com) + +Automation evolution +====== + +In my experience, scripts and macros almost never end up the way they start. This shouldn’t be a surprise. Just as spending time performing a particular task makes you realize it should be automated, spending time working with the automation makes you realize how it can be improved. Contra [XKCD][3], this doesn’t mean the decision to automate a task puts you on an endless treadmill of tweaking that’s never worth the time you invest. It means you’re continuing to think about how you do things and how your methods can be improved. I have an example that I’ve been working on for years. + +Two of the essential but dull parts of my job involve sending out invoices to clients and following up when those invoices aren’t paid on time. I’ve gradually built up a system to handle both of these interrelated duties. I’ve written about certain details before, but here I want to talk about how and why the system has evolved. + +It started with [TextExpander][4] snippets. One was for the text of the email that accompanied the invoice when it was first sent, and it looked like this (albeit less terse): + +``` +Attached is invoice A for $B on project C. Payment is due on D. +``` + +where the A, B, C, and D were [fill-in fields][5]. Similarly, there was a snippet for the followup emails. + +``` +The attached invoice, X for $Y on project Z, is still outstanding +and is now E days old. Pay up. +``` + +While these snippets was certainly better than typing this boilerplate out again and again, they weren’t using the computer for what it’s good at: looking things up and calculating. The invoices are PDFs that came out of my company’s accounting system and contain the information for X, Y, Z, and D. The age of the invoice, E, can be calculated from D and the current date. + +So after a month or two of using the snippets, I wrote an invoicing script in Python that read the invoice PDF and created an email message with all of the parts filled in. It also added a subject line and used a project database to look up the client’s email address to put in the To field. A similar script created a dunning email message. Both of these scripts could be run from the Terminal and took the invoice PDF as their argument, e.g., + +``` +invoice 12345.pdf +``` + +and + +``` +dun 12345.pdf +``` + +I should mention that these scripts created the email messages, but they didn’t send them. Sometimes I need to add an extra sentence or two to handle particular situations, and these scripts stopped short of sending so I could do that. + +It didn’t take very long for me to realize that opening a Terminal window just to run a single command was itself a waste of time. I used Automator to add Quick Action workflows that run the `invoice` and `dun` scripts to the Services menu. That allowed me to run the scripts by right-clicking on an invoice PDF file in the Finder. + +This system lasted quite a while. Eventually, though, I decided it was foolish to rely on my memory (or periodic checking of my outstanding invoices) to decide when to send out the followup emails on unpaid bills. I added a section to the `invoice` script that created a reminder along with the invoicing email. The reminder went in the Invoices list of the Reminders app and was given a due date of the first Tuesday at least 45 days after the invoice date. My invoices are net 30, so 45 days seemed like a good starting time for followups. And rather than having the reminder pop up on any day of the week, I set it to Tuesday—early in the week but unlikely to be on a holiday.1 + +Changing the `invoice` script changed the behavior of the Services menu item that called it; I didn’t have to make any changes in Automator. + +This system was the state of the art until it hit me that I could write a script that checked Reminders for every invoice that was past due and run the `dun` script on all of them, creating a series of followup emails in one fell swoop. I wrote this script as a combination of Python and AppleScript and embedded it in a [Keyboard Maestro][6] macro. With this macro in place, I no longer had to hunt for the invoices to right-click on. + +A couple of weeks ago, after reading Federico Viticci’s article on [using a Mac from iOS][7], I began thinking about the hole in my followup system: I have to be at my Mac to run Keyboard Maestro. What if I’m traveling on Tuesday and want to send out followup emails from my iPhone or iPad? OK, sure, I could use Screens to connect to the Mac and run the Keyboard Maestro macro that way, but that’s very slow and clumsy over a cellular network connection, especially when trying to manipulate windows on a 27″ iMac screen as viewed through an iPhone-sized keyhole. + +The obvious solution, which wasn’t obvious to me until I’d thought of and rejected a few other ideas, was to change the `dun` script to create and save the followup email. Saving the email puts it in the Drafts folder, which I can get at from all of my devices. I also changed the Keyboard Maestro macro that executes the `dun` script on every overdue invoice to run every Tuesday morning at 5:00 am. When the reminders pop up later in the day, the emails are already written and waiting for me in the Drafts folder. + +Yesterday was the first “live” test of the new system. I was in an airport restaurant—nothing but the best cuisine for me—when my watch buzzed with reminders for two overdue invoices. I pulled out my phone, opened Mail, and there were the emails, waiting to be sent. In this case, I didn’t have to edit the messages before sending, but it wouldn’t have been a big deal if I had—no more difficult than writing any other email from my phone. + +Am I done with this? History suggests I’m not, and I’m OK with that. By getting rid of more scutwork, I’ve made myself better at following up on old invoices, and my average time-to-collection has improved. Even XKCD would think that’s worth the effort. + +-------------------------------------------------------------------------------- + +via: https://leancrew.com/all-this/2019/02/automation-evolution/ + +作者：[Dr.Drang][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://leancrew.com +[b]: https://github.com/lujun9972 +[1]: https://leancrew.com/all-this/2019/02/regex-groups-and-numerals/ +[2]: https://leancrew.com/all-this/2019/02/transparency/ +[3]: https://xkcd.com/1319/ +[4]: https://textexpander.com/ +[5]: https://textexpander.com/help/desktop/fillins.html +[6]: https://www.keyboardmaestro.com/main/ +[7]: https://www.macstories.net/ipad-diaries/ipad-diaries-using-a-mac-from-ios-part-1-finder-folders-siri-shortcuts-and-app-windows-with-keyboard-maestro/ diff --git a/sources/tech/20190222 Q4OS Linux Revives Your Old Laptop with Windows- Looks.md b/sources/tech/20190222 Q4OS Linux Revives Your Old Laptop with Windows- Looks.md new file mode 100644 index 0000000000..93549ac45b --- /dev/null +++ b/sources/tech/20190222 Q4OS Linux Revives Your Old Laptop with Windows- Looks.md @@ -0,0 +1,192 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Q4OS Linux Revives Your Old Laptop with Windows’ Looks) +[#]: via: (https://itsfoss.com/q4os-linux-review) +[#]: author: (John Paul https://itsfoss.com/author/john/) + +Q4OS Linux Revives Your Old Laptop with Windows’ Looks +====== + +There are quite a few Linux distros available that seek to make new users feel at home by [imitating the look and feel of Windows][1]. Today, we’ll look at a distro that attempts to do this with limited success We’ll be looking at [Q4OS][2]. + +### Q4OS Linux focuses on performance on low hardware + +![Q4OS Linux desktop after first boot][3]Q4OS after first boot + +> Q4OS is a fast and powerful operating system based on the latest technologies while offering highly productive desktop environment. We focus on security, reliability, long-term stability and conservative integration of verified new features. System is distinguished by speed and very low hardware requirements, runs great on brand new machines as well as legacy computers. It is also very applicable for virtualization and cloud computing. +> +> Q4OS Website + +Q4OS currently has two different release branches: 2.# Scorpion and 3.# Centaurus. Scorpion is the Long-Term-Support (LTS) release and will be supported for five years. That support should last until 2022. The most recent version of Scorpion is 2.6, which is based on [Debian][4] 9 Stretch. Centaurus is considered the testing branch and is based on Debian Buster. Centaurus will become the LTS when Debian Buster becomes stable. + +Q4OS is one of the few Linux distros that still support both 32-bit and 64-bit. It has also been ported to ARM devices, specifically the Raspberry PI and the PineBook. + +The one major thing that separates Q4OS from the majority of Linux distros is their use of the Trinity Desktop Environment as the default desktop environment. + +#### The not-so-famous Trinity Desktop Environment + +![][5]Trinity Desktop Environment + +I’m sure that most people are unfamiliar with the [Trinity Desktop Environment (TDE)][6]. I didn’t know until I discovered Q4OS a couple of years ago. TDE is a fork of [KDE][7], specifically KDE 3.5. TDE was created by Timothy Pearson and the first release took place in April 2010. + +From what I read, it sounds like TDE was created for the same reason as [MATE][8]). Early versions of KDE 4 were prone to crash and users were unhappy with the direction the new release was taking, it was decided to fork the previous release. That is where the similarities end. MATE has taken on a life of its own and grew to become an equal among desktop environments. Development of TDE seems to have slowed. There were two years between the last two point releases. + +Quick side note: TDE uses its own fork of Qt 3, named TQt. + +#### System Requirements + +According to the [Q4OS download page][9], the system requirements differ based on the desktop environment you install. + +**TDE Version** + + * At least 300MHz CPU + * 128 MB of RAM + * 3 GB Storage + + + +**KDE Version** + + * At least 1GHz CPU + * 1 GB of RAM + * 5 GB Storage + + + +You can see from the system requirements that Q4OS is a [lightweight Linux distribution suitable for older computers][10]. + +#### Included apps by default + +The following applications are included in the full install of Q4OS: + + * Google Chrome + * Thunderbird + * LibreOffice + * VLC player + * Konqueror browser + * Dolphin file manager + * AisleRiot Solitaire + * Konsole + * Software Center + + + * KMines + * Ockular + * KBounce + * DigiKam + * Kooka + * KolourPaint + * KSnapshot + * Gwenview + * Ark + + + * KMail + * SMPlayer + * KRec + * Brasero + * Amarok player + * qpdfview + * KOrganizer + * KMag + * KNotes + + + +Of course, you can install additional applications through the software center. Since Q4OS is based on Debian, you can also [install applications from deb packages][11]. + +#### Q4OS can be installed from within Windows + +I was able to successfully install TrueOS on my Dell Latitude D630 without any issues. This laptop has an Intel Centrino Duo Core processor running at 2.00 GHz, NVIDIA Quadro NVS 135M graphics chip, and 4 GB of RAM. + +You have a couple of options to choose from when installing Q4OS. You can either install Q4OS with a CD (Live or install) or you can install it from inside Window. The Windows installer asks for the drive location you want to install to, how much space you want Q4OS to take up and what login information do you want to use. + +![][12]Q4OS Windows installer + +Compared to most distros, the Live ISOs are small. The KDE version weighs less than 1GB and the TDE version is just a little north of 500 MB. + +### Experiencing Q4OS: Feels like older Windows versions + +Please note that while there is a KDE installation ISO, I used the TDE installation ISO. The KDE Live CD is a recent addition, so TDE is more in line with the project’s long term goals. + +When you boot into Q4OS for the first time, it feels like you jumped through a time portal and are staring at Windows 2000. The initial app offerings are very slim, you have access to a file manager, a web browser and not much else. There isn’t even a screenshot tool installed. + +![][13]Konqueror film manager + +When you try to use the TDE browser (Konqueror), a dialog box pops up recommending using the Desktop Profiler to [install Google Chrome][14] or some other recent web browser. + +The Desktop Profiler allows you to choose between a bare-bones, basic or full desktop and which desktop environment you wish to use as default. You can also use the Desktop Profiler to install other desktop environments, such as MATE, Xfce, LXQT, LXDE, Cinnamon and GNOME. + +![Q4OS Welcome Screen][15]![Q4OS Welcome Screen][15]Q4OS Welcome Screen + +Q4OS comes with its own application center. However, the offerings are limited to less than 20 options, including Synaptic, Google Chrome, Chromium, Firefox, LibreOffice, Update Manager, VLC, Multimedia codecs, Thunderbird, LookSwitcher, NVIDIA drivers, Network Manager, Skype, GParted, Wine, Blueman, X2Go server, X2Go Client, and Virtualbox additions. + +![][16]Q4OS Software Centre + +If you want to install anything else, you need to either use the command line or the [synaptic package manager][17]. Synaptic is a very good package manager and has been very serviceable for many years, but it isn’t quite newbie friendly. + +If you install an application from the Software Centre, you are treated to an installer that looks a lot like a Windows installer. I can only imagine that this is for people converting to Linux from Windows. + +![][18]Firefox installer + +As I mentioned earlier, when you boot into Q4OS’ desktop for the first time it looks like something out of the 1990s. Thankfully, you can install a utility named LookSwitcher to install a different theme. Initially, you are only shown half a dozen themes. There are other themes that are considered works-in-progress. You can also enhance the default theme by picking a more vibrant background and making the bottom panel transparent. + +![][19]Q4OS using the Debonair theme + +### Final Thoughts on Q4OS + +I may have mentioned a few times in this review that Q4OS looks like a dated version of Windows. It is obviously a very conscious decision because great care was taken to make even the control panel and file manager look Windows-eque. The problem is that it reminds me more of [ReactOS][20] than something modern. The Q4OS website says that it is made using the latest technology. The look of the system disagrees and will probably put some new users off. + +The fact that the install ISOs are smaller than most means that they are very quick to download. Unfortunately, it also means that if you want to be productive, you’ll have to spend quite a bit of time downloading software, either manually or automatically. You’ll also need an active internet connection. There is a reason why most ISOs are several gigabytes. + +I made sure to test the Windows installer. I installed a test copy of Windows 10 and ran the Q4OS installer. The process took a few minutes because the installer, which is less than 10 MB had to download an ISO. When the process was done, I rebooted. I selected Q4OS from the menu, but it looked like I was booting into Windows 10 (got the big blue circle). I thought that the install failed, but I eventually got to Q4OS. + +One of the few things that I liked about Q4OS was how easy it was to install the NVIDIA drivers. After I logged in for the first time, a little pop-up told me that there were NVIDIA drivers available and asked me if I wanted to install them. + +Using Q4OS was definitely an interesting experience, especially using TDE for the first time and the Windows look and feel. However, the lack of apps in the Software Centre and some of the design choices stop me from recommending this distro. + +**Do you like Q4OS?** + +Have you ever used Q4OS? What is your favorite Debian-based distro? Please let us know in the comments below. + +If you found this article interesting, please take a minute to share it on social media, Hacker News or [Reddit][21]. + + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/q4os-linux-review + +作者：[John Paul][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/john/ +[b]: https://github.com/lujun9972 +[1]: https://itsfoss.com/windows-like-linux-distributions/ +[2]: https://q4os.org/ +[3]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/q4os1.jpg?resize=800%2C500&ssl=1 +[4]: https://www.debian.org/ +[5]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/q4os4.jpg?resize=800%2C412&ssl=1 +[6]: https://www.trinitydesktop.org/ +[7]: https://en.wikipedia.org/wiki/KDE +[8]: https://en.wikipedia.org/wiki/MATE_(software +[9]: https://q4os.org/downloads1.html +[10]: https://itsfoss.com/lightweight-linux-beginners/ +[11]: https://itsfoss.com/list-installed-packages-ubuntu/ +[12]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/q4os-windows-installer.jpg?resize=800%2C610&ssl=1 +[13]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/02/q4os2.jpg?resize=800%2C606&ssl=1 +[14]: https://itsfoss.com/install-chrome-ubuntu/ +[15]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/q4os10.png?ssl=1 +[16]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/q4os3.jpg?resize=800%2C507&ssl=1 +[17]: https://www.nongnu.org/synaptic/ +[18]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/02/q4os5.jpg?resize=800%2C616&ssl=1 +[19]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/q4os8Debonaire.jpg?resize=800%2C500&ssl=1 +[20]: https://www.reactos.org/ +[21]: http://reddit.com/r/linuxusersgroup +[22]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/q4os1.jpg?fit=800%2C500&ssl=1 diff --git a/sources/tech/20190223 Regex groups and numerals.md b/sources/tech/20190223 Regex groups and numerals.md new file mode 100644 index 0000000000..c24505ee6b --- /dev/null +++ b/sources/tech/20190223 Regex groups and numerals.md @@ -0,0 +1,60 @@ +[#]: collector: (lujun9972) +[#]: translator: (geekpi) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Regex groups and numerals) +[#]: via: (https://leancrew.com/all-this/2019/02/regex-groups-and-numerals/) +[#]: author: (Dr.Drang https://leancrew.com) + +Regex groups and numerals +====== + +A week or so ago, I was editing a program and decided I should change some variable names. I thought it would be a simple regex find/replace, and it was. Just not as simple as I thought. + +The variables were named `a10`, `v10`, and `x10`, and I wanted to change them to `a30`, `v30`, and `x30`, respectively. I brought up BBEdit’s Find window and entered this: + +![Mistaken BBEdit replacement pattern][2] + +I couldn’t just replace `10` with `30` because there were instances of `10` in the code that weren’t related to the variables. And because I think I’m clever, I didn’t want to do three non-regex replacements, one each for `a10`, `v10`, and `x10`. But I wasn’t clever enough to notice the blue coloring in the replacement pattern. Had I done so, I would have seen that BBEdit was interpreting my replacement pattern as “Captured group 13, followed by `0`” instead of “Captured group 1, followed by `30`,” which was what I intended. Since captured group 13 was blank, all my variable names were replaced with `0`. + +You see, BBEdit can capture up to 99 groups in the search pattern and, strictly speaking, we should use two-digit numbers when referring to them in the replacement pattern. But in most cases, we can use `\1` through `\9` instead of `\01` through `\09` because there’s no ambiguity. In other words, if I had been trying to change `a10`, `v10`, and `x10` to `az`, `vz`, and `xz`, a replacement pattern of `\1z` would have been just fine, because the trailing `z` means there’s no way to misinterpret the intent of the `\1` in that pattern. + +So after undoing the replacement, I changed the pattern to this, + +![Two-digit BBEdit replacement pattern][3] + +and all was right with the world. + +There was another option: a named group. Here’s how that would have looked, using `var` as the pattern name: + +![Named BBEdit replacement pattern][4] + +I don’t think I’ve ever used a named group in any situation, whether the regex was in a text editor or a script. My general feeling is that if the pattern is so complicated I have to use variables to keep track of all the groups, I should stop and break the problem down into smaller parts. + +By the way, you may have heard that BBEdit is celebrating its [25th anniversary][5] of not sucking. When a well-documented app has such a long history, the manual starts to accumulate delightful callbacks to the olden days. As I was looking up the notation for named groups in the BBEdit manual, I ran across this note: + +![BBEdit regex manual excerpt][6] + +BBEdit is currently on Version 12.5; Version 6.5 came out in 2001. But the manual wants to make sure that long-time customers (I believe it was on Version 4 when I first bought it) don’t get confused by changes in behavior, even when those changes occurred nearly two decades ago. + + +-------------------------------------------------------------------------------- + +via: https://leancrew.com/all-this/2019/02/regex-groups-and-numerals/ + +作者：[Dr.Drang][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://leancrew.com +[b]: https://github.com/lujun9972 +[1]: https://leancrew.com/all-this/2019/02/automation-evolution/ +[2]: https://leancrew.com/all-this/images2019/20190223-Mistaken%20BBEdit%20replacement%20pattern.png (Mistaken BBEdit replacement pattern) +[3]: https://leancrew.com/all-this/images2019/20190223-Two-digit%20BBEdit%20replacement%20pattern.png (Two-digit BBEdit replacement pattern) +[4]: https://leancrew.com/all-this/images2019/20190223-Named%20BBEdit%20replacement%20pattern.png (Named BBEdit replacement pattern) +[5]: https://merch.barebones.com/ +[6]: https://leancrew.com/all-this/images2019/20190223-BBEdit%20regex%20manual%20excerpt.png (BBEdit regex manual excerpt) diff --git a/translated/talk/20181220 7 CI-CD tools for sysadmins.md b/translated/talk/20181220 7 CI-CD tools for sysadmins.md new file mode 100644 index 0000000000..fe00691a9a --- /dev/null +++ b/translated/talk/20181220 7 CI-CD tools for sysadmins.md @@ -0,0 +1,134 @@ +[#]: collector: (lujun9972) +[#]: translator: (jdh8383) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (7 CI/CD tools for sysadmins) +[#]: via: (https://opensource.com/article/18/12/cicd-tools-sysadmins) +[#]: author: (Dan Barker https://opensource.com/users/barkerd427) + +系统管理员的 7 个 CI/CD 工具 +====== +本文是一篇简单指南：介绍一些常见的开源 CI/CD 工具。 + + +虽然持续集成、持续交付和持续部署（CI/CD）在开发者社区里已经存在很多年，一些机构在运维部门也有实施经验，但大多数公司并没有做这样的尝试。对于很多机构来说，让运维团队能够像他们的开发同行一样熟练操作 CI/CD 工具，已经变得十分必要了。 + +无论是基础设施、第三方应用还是内部开发的应用，都可以开展 CI/CD 实践。尽管你会发现有很多不同的工具，但它们都有着相似的设计模型。而且可能最重要的一点是：通过带领你的公司进行这些实践，会让你在公司内部变得举足轻重，成为他人学习的榜样。 + +一些机构在自己的基础设施上已有多年的 CI/CD 实践经验，常用的工具包括 [Ansible][1]、[Chef][2] 或者 [Puppet][3]。另一些工具，比如 [Test Kitchen][4]，允许在最终要部署应用的基础设施上运行测试。事实上，如果使用更高级的配置方法，你甚至可以将应用部署到有真实负载的仿真“生产环境”上，来运行应用级别的测试。然而，单单是能够测试基础设施就是一项了不起的成就了。配置管理工具 Terraform 可以通过 Test Kitchen 来快速创建[可复用][6]的基础设施配置，这比它的前辈要强不少。再加上 Linux 容器和 Kubernetes，在数小时内，你就可以创建一套类似于生产环境的配置参数和系统资源，来测试整个基础设施和其上部署的应用，这在以前可能需要花费几个月的时间。而且，删除和再次创建整个测试环境也非常容易。 + +当然，作为初学者，你也可以把网络配置和 DDL（数据定义语言）文件加入版本控制，然后开始尝试一些简单的 CI/CD 流程。虽然只能帮你检查一下语义语法，但实际上大多数用于开发的管道（pipeline）都是这样起步的。只要你把脚手架搭起来，建造就容易得多了。而一旦起步，你就会发现各种真实的使用场景。 + +举个例子，我经常会在公司内部写新闻简报，我使用 [MJML][7] 制作邮件模板，然后把它加入版本控制。我一般会维护一个 web 版本，但是一些同事喜欢 PDF 版，于是我创建了一个[管道][8]。每当我写好一篇新闻稿，就在 Gitlab 上提交一个合并请求。这样做会自动创建一个 index.html 文件，生成这篇新闻稿的 HTML 和 PDF 版链接。HTML 和 PDF 文件也会在管道里同时生成。除非有人来检查确认，这些文件不会被直接发布出去。使用 GitLab Pages 发布这个网站后，我就可以下载一份 HTML 版，用来发送新闻简报。未来，我会修改这个流程，当合并请求成功或者在某个审核步骤后，自动发出对应的新闻稿。这些处理逻辑并不复杂，但的确为我节省了不少时间。实际上这些工具最核心的用途就是替你节省时间。 + +关键是要在抽象层创建出工具，这样稍加修改就可以处理不同的问题。值得留意的是，我创建的这套流程几乎不需要任何代码，除了一些[轻量级的 HTML 模板][9]，一些[把 HTML 文件转换成 PDF 的 nodejs 代码][10]，还有一些[生成 index 页面的 nodejs 代码][11]。 + +这其中一些东西可能看起来有点复杂，但其中大部分都源自我使用的不同工具的教学文档。而且很多开发人员也会乐意跟你合作，因为他们在完工时会发现这些东西也挺有用。上面我提供的那些代码链接是给 [DevOps KC][12]（一个地方性DevOps组织） 发送新闻简报用的，其中大部分用来创建网站的代码来自我在内部新闻简报项目上所作的工作。 + +下面列出的大多数工具都可以提供这种类型的交互，但是有些工具提供的模型略有不同。这一领域新兴的模型是用声明式的方法例如 YAML 来描述一个管道，其中的每个阶段都是短暂而幂等的。许多系统还会创建[有向无环图（DAG）][13]，来确保管道上不同的阶段排序的正确性。 + +这些阶段一般运行在 Linux 容器里，和普通的容器并没有区别。有一些工具，比如 [Spinnaker][14]，只关注部署组件，而且提供一些其他工具没有的操作特性。[Jenkins][15] 则通常把管道配置存成 XML 格式，大部分交互都可以在图形界面里完成，但最新的方案是使用[领域专用语言（DSL）][16]如[Groovy][17]。并且，Jenkins 的任务（job）通常运行在各个节点里，这些节点上会装一个专门的 Java 程序还有一堆混杂的插件和预装组件。 + +Jenkins 在自己的工具里引入了管道的概念，但使用起来却并不轻松，甚至包含一些禁区。最近，Jenkins 的创始人决定带领社区向新的方向前进，希望能为这个项目注入新的活力，把 CI/CD 真正推广开(译者注：详见后面的 Jenkins 章节)。我认为其中最有意思的想法是构建一个云原生 Jenkins，能把 Kubernetes 集群转变成 Jenkins CI/CD 平台。 + +当你更多地了解这些工具并把实践带入你的公司和运维部门，你很快就会有追随者，因为你有办法提升自己和别人的工作效率。我们都有多年积累下来的技术债要解决，如果你能给同事们提供足够的时间来处理这些积压的工作，他们该会有多感激呢？不止如此，你的客户也会开始看到应用变得越来越稳定，管理层会把你看作得力干将，你也会在下次谈薪资待遇或参加面试时更有底气。 + +让我们开始深入了解这些工具吧，我们将对每个工具做简短的介绍，并分享一些有用的链接。 + +### GitLab CI + +GitLab 可以说是 CI/CD 领域里新登场的玩家，但它却在 [Forrester（一个权威调研机构） 的调查报告][20]中位列第一。在一个高水平、竞争充分的领域里，这是个了不起的成就。是什么让 GitLab CI 这么成功呢？它使用 YAML 文件来描述整个管道。另有一个功能叫做 Auto DevOps，可以为较简单的项目自动生成管道，并且包含多种内置的测试单元。这套系统使用 [Herokuish buildpacks][21]来判断语言的种类以及如何构建应用。它和 Kubernetes 紧密整合，可以根据不同的方案将你的应用自动部署到 Kubernetes 集群，比如灰度发布、蓝绿部署等。 + +除了它的持续集成功能，GitLab 还提供了许多补充特性，比如：将 Prometheus 和你的应用一同部署，以提供监控功能；通过 GitLab 提供的 Issues、Epics 和 Milestones 功能来实现项目评估和管理；管道中集成了安全检测功能，多个项目的检测结果会聚合显示；你可以通过 GitLab 提供的网页版 IDE 在线编辑代码，还可以快速查看管道的预览或执行状态。 + +### GoCD + +GoCD 是由老牌软件公司 Thoughtworks 出品，这已经足够证明它的能力和效率。对我而言，GoCD 最具亮点的特性是它的[价值流视图（VSM）][22]。实际上，一个管道的输出可以变成下一个管道的输入，从而把管道串联起来。这样做有助于提高不同开发团队在整个开发流程中的独立性。比如在引入 CI/CD 系统时，有些成立较久的机构希望保持他们各个团队相互隔离，这时候 VSM 就很有用了：让每个人都使用相同的工具就很容易在 VSM 中发现工作流程上的瓶颈，然后可以按图索骥调整团队或者想办法提高工作效率。 + +为公司的每个产品配置 VSM 是非常有价值的；GoCD 可以使用 [JSON 或 YAML 格式存储配置][23]，还能以可视化的方式展示等待时间，这让一个机构能有效减少学习它的成本。刚开始使用 GoCD 创建你自己的流程时，建议使用人工审核的方式。让每个团队也采用人工审核，这样你就可以开始收集数据并且找到可能的瓶颈点。 + +### Travis CI + +我使用的第一个软件既服务（SaaS）类型的 CI 系统就是 Travis CI，体验很不错。管道配置以源码形式用 YAML 保存，它与 GitHub 等工具无缝整合。我印象中管道从来没有失效过，因为 Travis CI 的在线率很高。除了 SaaS 版之外，你也可以使用自行部署的版本。我还没有自行部署过，它的组件非常多，要全部安装的话，工作量就有点吓人了。我猜更简单的办法是把它部署到 Kubernetes 上，[Travis CI 提供了 Helm charts][26]，这些 charts 目前不包含所有要部署的组件，但我相信以后会越来越丰富的。如果你不想处理这些细枝末节的问题，还有一个企业版可以试试。 + +假如你在开发一个开源项目，你就能免费使用 SaaS 版的 Travis CI，享受顶尖团队提供的优质服务！这样能省去很多麻烦，你可以在一个相对通用的平台上（如 GitHub）研发开源项目，而不用找服务器来运行任何东西。 + +### Jenkins + +Jenkins在 CI/CD 界绝对是元老级的存在，也是事实上的标准。我强烈建议你读一读这篇文章："[Jenkins: Shifting Gears][27]"，作者 Kohsuke 是 Jenkins 的创始人兼 CloudBees 公司 CTO。这篇文章契合了我在过去十年里对 Jenkins 及其社区的感受。他在文中阐述了一些这几年呼声很高的需求，我很乐意看到 CloudBees 引领这场变革。长期以来，Jenkins 对于非开发人员来说有点难以接受，并且一直是其管理员的重担。还好，这些问题正是他们想要着手解决的。 + +[Jenkins 配置既代码][28]（JCasC）应该可以帮助管理员解决困扰了他们多年的配置复杂性问题。与其他 CI/CD 系统类似，只需要修改一个简单的 YAML 文件就可以完成 Jenkins 主节点的配置工作。[Jenkins Evergreen][29] 的出现让配置工作变得更加轻松，它提供了很多预设的使用场景，你只管套用就可以了。这些发行版会比官方的标准版本 Jenkins 更容易维护和升级。 + +Jenkins 2 引入了两种原生的管道（pipeline）功能，我在 LISA（一个系统架构和运维大会） 2017 年的研讨会上已经[讨论过了][30]。这两种功能都没有 YAML 简便，但在处理复杂任务时它们很好用。 + +[Jenkins X][31] 是 Jenkins 的一个全新变种，用来实现云端原生 Jenkins（至少在用户看来是这样）。它会使用 JCasC 及 Evergreen，并且和 Kubernetes 整合的更加紧密。对于 Jenkins 来说这是个令人激动的时刻，我很乐意看到它在这一领域的创新，并且继续发挥领袖作用。 + +### Concourse CI + +我第一次知道 Concourse 是通过 Pivotal Labs 的伙计们介绍的，当时它处于早期 beta 版本，而且那时候也很少有类似的工具。这套系统是基于微服务构建的，每个任务运行在一个容器里。它独有的一个优良特性是能够在你本地系统上运行任务，体现你本地的改动。这意味着你完全可以在本地开发（假设你已经连接到了 Concourse 的服务器），像在真实的管道构建流程一样从你本地构建项目。而且，你可以在修改过代码后从本地直接重新运行构建，来检验你的改动结果。 + +Concourse 还有一个简单的扩展系统，它依赖于资源这一基础概念。基本上，你想给管道添加的每个新功能都可以用一个 Docker 镜像实现，并作为一个新的资源类型包含在你的配置中。这样可以保证每个功能都被封装在一个不易改变的独立工件中，方便对其单独修改和升级，改变其中一个时不会影响其他构建。 + +### Spinnaker + +Spinnaker 出自 Netflix，它更关注持续部署而非持续集成。它可以与其他工具整合，比如Travis 和 Jenkins，来启动测试和部署流程。它也能与 Prometheus、Datadog 这样的监控工具集成，参考它们提供的指标来决定如何部署。例如，在一次金丝雀发布（canary deployment）里，我们可以根据收集到的相关监控指标来做出判断：最近的这次发布是否导致了服务降级，应该立刻回滚；还是说看起来一切OK，应该继续执行部署。 + +谈到持续部署，一些另类但却至关重要的问题往往被忽略掉了，说出来可能有点让人困惑：Spinnaker 可以帮助持续部署不那么“持续”。在整个应用部署流程期间，如果发生了重大问题，它可以让流程停止执行，以阻止可能发生的部署错误。但它也可以在最关键的时刻让人工审核强制通过，发布新版本上线，使整体收益最大化。实际上，CI/CD 的主要目的就是在商业模式需要调整时，能够让待更新的代码立即得到部署。 + +### Screwdriver + +Screwdriver 是个简单而又强大的软件。它采用微服务架构，依赖像 Nomad、Kubernetes 和 Docker 这样的工具作为执行引擎。官方有一篇很不错的[部署教学文档][34]，介绍了如何将它部署到 AWS 和 Kubernetes 上，但如果相应的 [Helm chart][35] 也完成的话，就更完美了。 + +Screwdriver 也使用 YAML 来描述它的管道，并且有很多合理的默认值，这样可以有效减少各个管道重复的配置项。用配置文件可以组织起高级的工作流，来描述各个 job 间复杂的依赖关系。例如，一项任务可以在另一个任务开始前或结束后运行；各个任务可以并行也可以串行执行；更赞的是你可以预先定义一项任务，只在特定的 pull request 请求时被触发，而且与之有依赖关系的任务并不会被执行，这能让你的管道具有一定的隔离性：什么时候被构造的工件应该被部署到生产环境，什么时候应该被审核。 + +以上只是我对这些 CI/CD 工具的简单介绍，它们还有许多很酷的特性等待你深入探索。而且它们都是开源软件，可以自由使用，去部署一下看看吧，究竟哪个才是最适合你的那个。 + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/12/cicd-tools-sysadmins + +作者：[Dan Barker][a] +选题：[lujun9972][b] +译者：[jdh8383](https://github.com/jdh8383) +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/barkerd427 +[b]: https://github.com/lujun9972 +[1]: https://www.ansible.com/ +[2]: https://www.chef.io/ +[3]: https://puppet.com/ +[4]: https://github.com/test-kitchen/test-kitchen +[5]: https://www.merriam-webster.com/dictionary/ephemeral +[6]: https://en.wikipedia.org/wiki/Idempotence +[7]: https://mjml.io/ +[8]: https://gitlab.com/devopskc/newsletter/blob/master/.gitlab-ci.yml +[9]: https://gitlab.com/devopskc/newsletter/blob/master/index/index.html +[10]: https://gitlab.com/devopskc/newsletter/blob/master/html-to-pdf.js +[11]: https://gitlab.com/devopskc/newsletter/blob/master/populate-index.js +[12]: https://devopskc.com/ +[13]: https://en.wikipedia.org/wiki/Directed_acyclic_graph +[14]: https://www.spinnaker.io/ +[15]: https://jenkins.io/ +[16]: https://martinfowler.com/books/dsl.html +[17]: http://groovy-lang.org/ +[18]: https://about.gitlab.com/product/continuous-integration/ +[19]: https://gitlab.com/gitlab-org/gitlab-ce/ +[20]: https://about.gitlab.com/2017/09/27/gitlab-leader-continuous-integration-forrester-wave/ +[21]: https://github.com/gliderlabs/herokuish +[22]: https://www.gocd.org/getting-started/part-3/#value_stream_map +[23]: https://docs.gocd.org/current/advanced_usage/pipelines_as_code.html +[24]: https://docs.travis-ci.com/ +[25]: https://github.com/travis-ci/travis-ci +[26]: https://github.com/travis-ci/kubernetes-config +[27]: https://jenkins.io/blog/2018/08/31/shifting-gears/ +[28]: https://jenkins.io/projects/jcasc/ +[29]: https://github.com/jenkinsci/jep/blob/master/jep/300/README.adoc +[30]: https://danbarker.codes/talk/lisa17-becoming-plumber-building-deployment-pipelines/ +[31]: https://jenkins-x.io/ +[32]: https://concourse-ci.org/ +[33]: https://github.com/concourse/concourse +[34]: https://docs.screwdriver.cd/cluster-management/kubernetes +[35]: https://github.com/screwdriver-cd/screwdriver-chart diff --git a/translated/tech/20140114 Caffeinated 6.828：Lab 2 Memory Management.md b/translated/tech/20140114 Caffeinated 6.828：Lab 2 Memory Management.md deleted file mode 100644 index 39b20a33f0..0000000000 --- a/translated/tech/20140114 Caffeinated 6.828：Lab 2 Memory Management.md +++ /dev/null @@ -1,240 +0,0 @@ -# Caffeinated 6.828：实验 2：内存管理 - -### 简介 - -在本实验中，你将为你的操作系统写内存管理方面的代码。内存管理有两部分组成。 - -第一部分是内核的物理内存分配器，内核通过它来分配内存，以及在不需要时释放所分配的内存。分配器以页为单位分配内存，每个页的大小为 4096 字节。你的任务是去维护那个数据结构，它负责记录物理页的分配和释放，以及每个分配的页有多少进程共享它。本实验中你将要写出分配和释放内存页的全套代码。 - -第二个部分是虚拟内存的管理，它负责由内核和用户软件使用的虚拟内存地址到物理内存地址之间的映射。当使用内存时，x86 架构的硬件是由内存管理单元（MMU）负责执行映射操作来查阅一组页表。接下来你将要修改 JOS，以根据我们提供的特定指令去设置 MMU 的页表。 - -### 预备知识 - -在本实验及后面的实验中，你将逐步构建你的内核。我们将会为你提供一些附加的资源。使用 Git 去获取这些资源、提交自实验 1 以来的改变（如有需要的话）、获取课程仓库的最新版本、以及在我们的实验 2 （origin/lab2）的基础上创建一个称为 lab2 的本地分支： - -```c -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% -``` - -上面的 `git checkout -b` 命令其实做了两件事情：首先它创建了一个本地分支 `lab2`，它跟踪给我们提供课程内容的远程分支 `origin/lab2` ，第二件事情是，它更改的你的 `lab` 目录的内容反映到 `lab2` 分支上存储的文件中。Git 允许你在已存在的两个分支之间使用 `git checkout *branch-name*` 命令去切换，但是在你切换到另一个分支之前，你应该去提交那个分支上你做的任何出色的变更。 - -现在，你需要将你在 lab1 分支中的改变合并到 lab2 分支中，命令如下： - -```c -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% -``` - -在一些案例中，Git 或许并不能找到如何将你的更改与新的实验任务合并（例如，你在第二个实验任务中变更了一些代码的修改）。在那种情况下，你使用 git 命令去合并，它会告诉你哪个文件发生了冲突，你必须首先去解决冲突（通过编辑冲突的文件），然后使用 `git commit -a` 去重新提交文件。 - -实验 2 包含如下的新源代码，后面你将遍历它们： - -- inc/memlayout.h -- kern/pmap.c -- kern/pmap.h -- kern/kclock.h -- kern/kclock.c - -`memlayout.h` 描述虚拟地址空间的布局，这个虚拟地址空间是通过修改 `pmap.c`、`memlayout.h` 和 `pmap.h` 所定义的 *PageInfo* 数据结构来实现的，这个数据结构用于跟踪物理内存页面是否被释放。`kclock.c` 和 `kclock.h` 维护 PC 基于电池的时钟和 CMOS RAM 硬件，在 BIOS 中记录了 PC 上安装的物理内存数量，以及其它的一些信息。在 `pmap.c` 中的代码需要去读取这个设备硬件信息，以算出在这个设备上安装了多少物理内存，这些只是由你来完成的一部分代码：你不需要知道 CMOS 硬件工作原理的细节。 - -特别需要注意的是 `memlayout.h` 和 `pmap.h`，因为本实验需要你去使用和理解的大部分内容都包含在这两个文件中。你或许还需要去复习 `inc/mmu.h` 这个文件，因为它也包含了本实验中用到的许多定义。 - -开始本实验之前，记得去添加 `exokernel` 以获取 QEMU 的 6.828 版本。 - -### 实验过程 - -在你准备进行实验和写代码之前，先添加你的 `answers-lab2.txt` 文件到 Git 仓库，提交你的改变然后去运行 `make handin`。 - -```c -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 -``` - -正如前面所说的，我们将使用一个评级程序来分级你的解决方案，你可以在 `lab` 目录下运行 `make grade`，使用评级程序来测试你的内核。为了完成你的实验，你可以改变任何你需要的内核源代码和头文件。但毫无疑问的是，你不能以任何形式去改变或破坏评级代码。 - -### 第 1 部分：物理页面管理 - -操作系统必须跟踪物理内存页是否使用的状态。JOS 以页为最小粒度来管理 PC 的物理内存，以便于它使用 MMU 去映射和保护每个已分配的内存片段。 - -现在，你将要写内存的物理页分配器的代码。它使用链接到 `PageInfo` 数据结构的一组列表来保持对物理页的状态跟踪，每个列表都对应到一个物理内存页。在你能够写出剩下的虚拟内存实现之前，你需要先写出物理内存页面分配器，因为你的页表管理代码将需要去分配物理内存来存储页表。 - -> 练习 1 -> -> 在文件 `kern/pmap.c` 中，你需要去实现以下函数的代码（或许要按给定的顺序来实现）。 -> -> boot_alloc() -> -> mem_init()（只要能够调用 check_page_free_list() 即可） -> -> page_init() -> -> page_alloc() -> -> page_free() -> -> `check_page_free_list()` 和 `check_page_alloc()` 可以测试你的物理内存页分配器。你将需要引导 JOS 然后去看一下 `check_page_alloc()` 是否报告成功即可。如果没有报告成功，修复你的代码直到成功为止。你可以添加你自己的 `assert()` 以帮助你去验证是否符合你的预期。 - -本实验以及所有的 6.828 实验中，将要求你做一些检测工作，以便于你搞清楚它们是否按你的预期来工作。这个任务不需要详细描述你添加到 JOS 中的代码的细节。查找 JOS 源代码中你需要去修改的那部分的注释；这些注释中经常包含有技术规范和提示信息。你也可能需要去查阅 JOS、和 Intel 的技术手册、以及你的 6.004 或 6.033 课程笔记的相关部分。 - -### 第 2 部分：虚拟内存 - -在你开始动手之前，需要先熟悉 x86 内存管理架构的保护模式：即分段和页面转换。 - -> 练习 2 -> -> 如果你对 x86 的保护模式还不熟悉，可以查看 Intel 80386 参考手册的第 5 章和第 6 章。阅读这些章节（5.2 和 6.4）中关于页面转换和基于页面的保护。我们建议你也去了解关于段的章节；在虚拟内存和保护模式中，JOS 使用了分页、段转换、以及在 x86 上不能禁用的基于段的保护，因此你需要去理解这些基础知识。 - -### 虚拟地址、线性地址和物理地址 - -在 x86 的专用术语中，一个虚拟地址是由一个段选择器和在段中的偏移量组成。一个线性地址是在页面转换之前、段转换之后得到的一个地址。一个物理地址是段和页面转换之后得到的最终地址，它最终将进入你的物理内存中的硬件总线。 - - - -一个 C 指针是虚拟地址的“偏移量”部分。在 `boot/boot.S` 中我们安装了一个全局描述符表（GDT），它通过设置所有的段基址为 0，并且限制为 `0xffffffff` 来有效地禁用段转换。因此“段选择器”并不会生效，而线性地址总是等于虚拟地址的偏移量。在实验 3 中，为了设置权限级别，我们将与段有更多的交互。但是对于内存转换，我们将在整个 JOS 实验中忽略段，只专注于页转换。 - -回顾实验 1 中的第 3 部分，我们安装了一个简单的页表，这样内核就可以在 0xf0100000 链接的地址上运行，尽管它实际上是加载在 0x00100000 处的 ROM BIOS 的物理内存上。这个页表仅映射了 4MB 的内存。在实验中，你将要为 JOS 去设置虚拟内存布局，我们将从虚拟地址 0xf0000000 处开始扩展它，首先将物理内存扩展到 256MB，并映射许多其它区域的虚拟内存。 - -> 练习 3 -> -> 虽然 GDB 能够通过虚拟地址访问 QEMU 的内存，它经常用于在配置虚拟内存期间检查物理内存。在实验工具指南中复习 QEMU 的监视器命令，尤其是 `xp` 命令，它可以让你去检查物理内存。访问 QEMU 监视器，可以在终端中按 `Ctrl-a c`（相同的绑定返回到串行控制台）。 -> -> 使用 QEMU 监视器的 `xp` 命令和 GDB 的 `x` 命令去检查相应的物理内存和虚拟内存，以确保你看到的是相同的数据。 -> -> 我们的打过补丁的 QEMU 版本提供一个非常有用的 `info pg` 命令：它可以展示当前页表的一个简单描述，包括所有已映射的内存范围、权限、以及标志。Stock QEMU 也提供一个 `info mem` 命令用于去展示一个概要信息，这个信息包含了已映射的虚拟内存范围和使用了什么权限。 - -在 CPU 上运行的代码，一旦处于保护模式（这是在 boot/boot.S 中所做的第一件事情）中，是没有办法去直接使用一个线性地址或物理地址的。所有的内存引用都被解释为虚拟地址，然后由 MMU 来转换，这意味着在 C 语言中的指针都是虚拟地址。 - -例如在物理内存分配器中，JOS 内存经常需要在不反向引用的情况下，去维护作为地址的一个很难懂的值或一个整数。有时它们是虚拟地址，而有时是物理地址。为便于在代码中证明，JOS 源文件中将它们区分为两种：类型 `uintptr_t` 表示一个难懂的虚拟地址，而类型 `physaddr_trepresents` 表示物理地址。这些类型其实不过是 32 位整数（uint32_t）的同义词，因此编译器不会阻止你将一个类型的数据指派为另一个类型！因为它们都是整数（而不是指针）类型，如果你想去反向引用它们，编译器将报错。 - -JOS 内核能够通过将它转换为指针类型的方式来反向引用一个 `uintptr_t` 类型。相反，内核不能反向引用一个物理地址，因为这是由 MMU 来转换所有的内存引用。如果你转换一个 `physaddr_t` 为一个指针类型，并反向引用它，你或许能够加载和存储最终结果地址（硬件将它解释为一个虚拟地址），但你并不会取得你想要的内存位置。 - -总结如下： - -| C type | Address type | -| ------------ | ------------ | -| `T*` | Virtual | -| `uintptr_t` | Virtual | -| `physaddr_t` | Physical | - ->问题： -> ->假设下面的 JOS 内核代码是正确的，那么变量 `x` 应该是什么类型？uintptr_t 还是 physaddr_t ？ -> -> -> - -JOS 内核有时需要去读取或修改它知道物理地址的内存。例如，添加一个映射到页表，可以要求分配物理内存去存储一个页目录，然后去初始化它们。然而，内核也和其它的软件一样，并不能跳过虚拟地址转换，内核并不能直接加载和存储物理地址。一个原因是 JOS 将重映射从虚拟地址 0xf0000000 处物理地址 0 开始的所有的物理地址，以帮助内核去读取和写入它知道物理地址的内存。为转换一个物理地址为一个内核能够真正进行读写操作的虚拟地址，内核必须添加 0xf0000000 到物理地址以找到在重映射区域中相应的虚拟地址。你应该使用 KADDR(pa) 去做那个添加操作。 - -JOS 内核有时也需要能够通过给定的内核数据结构中存储的虚拟地址找到内存中的物理地址。内核全局变量和通过 `boot_alloc()` 分配的内存是加载到内核的这些区域中，从 0xf0000000 处开始，到全部物理内存映射的区域。因此，在这些区域中转变一个虚拟地址为物理地址时，内核能够只是简单地减去 0xf0000000 即可得到物理地址。你应该使用 PADDR(va) 去做那个减法操作。 - -### 引用计数 - -在以后的实验中，你将会经常遇到多个虚拟地址（或多个环境下的地址空间中）同时映射到相同的物理页面上。你将在 PageInfo 数据结构中用 pp_ref 字段来提供一个引用到每个物理页面的计数器。如果一个物理页面的这个计数器为 0，表示这个页面已经被释放，因为它不再被使用了。一般情况下，这个计数器应该等于相应的物理页面出现在所有页表下面的 UTOP 的次数（UTOP 上面的映射大都是在引导时由内核设置的，并且它从不会被释放，因此不需要引用计数器）。我们也使用它去跟踪到页目录的指针数量，反过来就是，页目录到页表的数量。 - -使用 `page_alloc` 时要注意。它返回的页面引用计数总是为 0，因此，一旦对返回页做了一些操作（比如将它插入到页表），`pp_ref` 就应该增加。有时这需要通过其它函数（比如，`page_instert`）来处理，而有时这个函数是直接调用 `page_alloc` 来做的。 - -### 页表管理 - -现在，你将写一套管理页表的代码：去插入和删除线性地址到物理地址的映射表，并且在需要的时候去创建页表。 - -> 练习 4 -> -> 在文件 `kern/pmap.c` 中，你必须去实现下列函数的代码。 -> -> pgdir_walk() -> -> boot_map_region() -> -> page_lookup() -> -> page_remove() -> -> page_insert() -> -> `check_page()`，调用 `mem_init()`，测试你的页表管理动作。在进行下一步流程之前你应该确保它成功运行。 - -### 第 3 部分：内核地址空间 - -JOS 分割处理器的 32 位线性地址空间为两部分：用户环境（进程），我们将在实验 3 中开始加载和运行，它将控制其上的布局和低位部分的内容，而内核总是维护对高位部分的完全控制。线性地址的定义是在 `inc/memlayout.h` 中通过符号 ULIM 来划分的，它为内核保留了大约 256MB 的虚拟地址空间。这就解释了为什么我们要在实验 1 中给内核这样的一个高位链接地址的原因：如是不这样做的话，内核的虚拟地址空间将没有足够的空间去同时映射到下面的用户空间中。 - -你可以在 `inc/memlayout.h` 中找到一个图表，它有助于你去理解 JOS 内存布局，这在本实验和后面的实验中都会用到。 - -### 权限和故障隔离 - -由于内核和用户的内存都存在于它们各自环境的地址空间中，因此我们需要在 x86 的页表中使用权限位去允许用户代码只能访问用户所属地址空间的部分。否则，用户代码中的 bug 可能会覆写内核数据，导致系统崩溃或者发生各种莫名其妙的的故障；用户代码也可能会偷窥其它环境的私有数据。 - -对于 ULIM 以上部分的内存，用户环境没有任何权限，只有内核才可以读取和写入这部分内存。对于 [UTOP,ULIM] 地址范围，内核和用户都有相同的权限：它们可以读取但不能写入这个地址范围。这个地址范围是用于向用户环境暴露某些只读的内核数据结构。最后，低于 UTOP 的地址空间是为用户环境所使用的；用户环境将为访问这些内核设置权限。 - -### 初始化内核地址空间 - -现在，你将去配置 UTOP 以上的地址空间：内核部分的地址空间。`inc/memlayout.h` 中展示了你将要使用的布局。我将使用函数去写相关的线性地址到物理地址的映射配置。 - -> 练习 5 -> -> 完成调用 `check_page()` 之后在 `mem_init()` 中缺失的代码。 - -现在，你的代码应该通过了 `check_kern_pgdir()` 和 `check_page_installed_pgdir()` 的检查。 - -> 问题： -> -> 1、在这个时刻，页目录中的条目（行）是什么？它们映射的址址是什么？以及它们映射到哪里了？换句话说就是，尽可能多地填写这个表： -> -> EntryBase Virtual AddressPoints to (logically): -> -> 1023 ? Page table for top 4MB of phys memory -> -> 1022 ? ? -> -> . ? ? -> -> . ? ? -> -> . ? ? -> -> 2 0x00800000 ? -> -> 1 0x00400000 ? -> -> 0 0x00000000 [see next question] -> -> 2、(来自课程 3) 我们将内核和用户环境放在相同的地址空间中。为什么用户程序不能去读取和写入内核的内存？有什么特殊机制保护内核内存？ -> -> 3、这个操作系统能够支持的最大的物理内存数量是多少？为什么？ -> -> 4、我们真实地拥有最大数量的物理内存吗？管理内存的开销有多少？这个开销可以减少吗？ -> -> 5、复习在 `kern/entry.S` 和 `kern/entrypgdir.c` 中的页表设置。一旦我们打开分页，EIP 中是一个很小的数字（稍大于 1MB）。在什么情况下，我们转而去运行在 KERNBASE 之上的一个 EIP？当我们启用分页并开始在 KERNBASE 之上运行一个 EIP 时，是什么让我们能够持续运行一个很低的 EIP？为什么这种转变是必需的？ - -### 地址空间布局的其它选择 - -在 JOS 中我们使用的地址空间布局并不是我们唯一的选择。一个操作系统可以在低位的线性地址上映射内核，而为用户进程保留线性地址的高位部分。然而，x86 内核一般并不采用这种方法，而 x86 向后兼容模式是不这样做的其中一个原因，这种模式被称为“虚拟 8086 模式”，处理器使用线性地址空间的最下面部分是“不可改变的”，所以，如果内核被映射到这里是根本无法使用的。 - -虽然很困难，但是设计这样的内核是有这种可能的，即：不为处理器自身保留任何固定的线性地址或虚拟地址空间，而有效地允许用户级进程不受限制地使用整个 4GB 的虚拟地址空间 —— 同时还要在这些进程之间充分保护内核以及不同的进程之间相互受保护！ - -将内核的内存分配系统进行概括类推，以支持二次幂为单位的各种页大小，从 4KB 到一些你选择的合理的最大值。你务必要有一些方法，将较大的分配单位按需分割为一些较小的单位，以及在需要时，将多个较小的分配单位合并为一个较大的分配单位。想一想在这样的一个系统中可能会出现些什么样的问题。 - -这个实验做完了。确保你通过了所有的等级测试，并记得在 `answers-lab2.txt` 中写下你对上述问题的答案。提交你的改变（包括添加 `answers-lab2.txt` 文件），并在 `lab` 目录下输入 `make handin` 去提交你的实验。 - ------- - -via: :9090**。 + +可以在 [Cockpit Project]][2] 中找到可以使用 Cockpit 的发行版列表以及安装说明。 + +没有额外的配置，Linux Cockpit 将无法识别 **sudo** 权限。如果你被禁止使用 Cockpit 进行更改，你将会在你点击的按钮上看到一个红色的国际禁止标志。 + +要使 sudo 权限有效，你需要确保用户位于 **/etc/group** 文件中的 **wheel**（RHEL）或 **adm** （Debian）组中，即服务器当以 root 用户身份登录 Cockpit 并且用户在登录 Cockpit 时选择“重用我的密码”时，已勾选了 Server Administrator。 + +在你管理的系统在千里之外或者没有控制台时，能使用图形界面控制也不错。虽然我喜欢在控制台上工作，但我偶然也乐于见到图形或者按钮。Linux Cockpit 为日常管理任务提供了非常有用的界面。 + +在 [Facebook][3] 和 [LinkedIn][4] 中加入 Network World 社区，对你喜欢的文章评论。 + +-------------------------------------------------------------------------------- + +via: https://www.networkworld.com/article/3340038/linux/sitting-in-the-linux-cockpit.html + +作者：[Sandra Henry-Stocker][a] +选题：[lujun9972][b] +译者：[geekpi](https://github.com/geekpi) +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://images.idgesg.net/images/article/2019/02/cockpit-activity-100787994-large.jpg +[2]: https://cockpit-project.org/running.html +[3]: https://www.facebook.com/NetworkWorld/ +[4]: https://www.linkedin.com/company/network-world diff --git a/translated/tech/20190217 How to Change User Password in Ubuntu -Beginner-s Tutorial.md b/translated/tech/20190217 How to Change User Password in Ubuntu -Beginner-s Tutorial.md new file mode 100644 index 0000000000..a2dfb77515 --- /dev/null +++ b/translated/tech/20190217 How to Change User Password in Ubuntu -Beginner-s Tutorial.md @@ -0,0 +1,129 @@ +[#]: collector: (lujun9972) +[#]: translator: (An-DJ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How to Change User Password in Ubuntu [Beginner’s Tutorial]) +[#]: via: (https://itsfoss.com/change-password-ubuntu) +[#]: author: (Abhishek Prakash https://itsfoss.com/author/abhishek/) + +Ubuntu下如何修改用户密码 [新手教程] +====== +**想要在Ubuntu下修改root用户的密码？那我们来学习下如何在Ubuntu Linux下修改任意用户的密码。我们会讨论在终端下修改和在图形界面(GUI)修改两种做法** + +那么，在Ubuntu下什么时候会需要修改密码呢？这里我给出如下两种场景。 + +当你刚安装[Ubuntu][1]系统时，你会创建一个用户并且为之设置一个密码。这个初始密码可能安全性较弱或者太过于复杂，你会想要对它做出修改。 + +如果你是系统管理员，你可能需要去修改在你管理的系统内其他用户的密码。 + +当然，你可能会有其他的一些原因做这样的一件事。不过现在问题来了，我们到底如何在Ubuntu或Linux系统下修改单个用户的密码呢？ + +在这个快速教程中，我将会展示给你在Ubuntu中如何使用命令行和图形界面(GUI)两种方式修改密码。 + +### 在Ubuntu中修改用户密码[通过命令行] + +![如何在Ubuntu Linux下修改用户密码][2] + +在Ubuntu下修改用户密码其实非常简单。事实上，在任何Linux发行版上修改的方式都是一样的，因为你要使用的是叫做 passwd 的普通Linux命令来达到此目的。 + +如果你想要修改你的当前密码，只需要简单地在终端执行此命令： + +``` +passwd +``` + +系统会要求你输入当前密码和两次新的密码。 + +在键入密码时，你不会从屏幕上看到任何东西。这在UNIX和Linux系统中是非常正常的表现。 + +``` +passwd + +Changing password for abhishek. + +(current) UNIX password: + +Enter new UNIX password: + +Retype new UNIX password: + +passwd: password updated successfully +``` + +由于这是你的管理员账户，你刚刚修改了Ubuntu下sudo的密码，但你甚至没有意识到这个操作。 + +![在Linux命令行中修改用户密码][3] + +如果你想要修改其他用户的密码，你也可以使用passwd命令来做。但是在这种情况下，你将不得不使用sudo。 + +``` +sudo passwd +``` + +如果你对密码已经做出了修改，不过之后忘记了，不要担心。你可以[很容易地在Ubuntu下重置密码][4]. + +### 修改Ubuntu下root用户密码 + +默认情况下，Ubuntu中root用户是没有密码的。不必惊讶，你并不是在Ubuntu下一直使用root用户。不太懂？让我快速地给你解释下。 + +当[安装Ubuntu][5]时，你会被强制创建一个用户。这个用户拥有管理员访问权限。这个管理员用户可以通过sudo命令获得root访问权限。但是，该用户使用的是自身的密码，而不是root账户的密码（因为就没有）。 + +你可以使用**passwd**命令来设置或修改root用户的密码。然而，在大多数情况下，你并不需要它，而且你不应该去做这样的事。 + +你将不得不使用sudo命令（对于拥有管理员权限的账户）。如果root用户的密码之前没有被设置，它会要求你设置。另外，你可以使用已有的root密码对它进行修改。 + +``` +sudo password root +``` + +### 在Ubuntu下使用图形界面（GUI）修改密码 + +我这里使用的是GNOME桌面环境，Ubuntu版本为18.04。这些步骤对于其他桌面环境和Ubuntu版本应该差别不大。 + +打开菜单（按下Windows/Super键）并搜索Settings。 + +在Settings中，向下滚动一段距离打开进入Details。 + +![在Ubuntu GNOME Settings中进入Details][6] + +在这里，点击Users获取系统下可见的所有用户。 + +![Ubuntu下用户设置][7] + +你可以选择任一你想要的用户，包括你的主要管理员账户。你需要先解锁用户并点击密码（password）区域。 + +![Ubuntu下修改用户密码][8] + +你会被要求设置密码。如果你正在修改的是你自己的密码，你将必须也输入当前使用的密码。 + +![Ubuntu下修改用户密码][9] + +做好这些后，点击上面的Change按钮，这样就完成了。你已经成功地在Ubuntu下修改了用户密码。 + +我希望这篇快速精简的小教程能够帮助你在Ubuntu下修改用户密码。如果你对此还有一些问题或建议，请在下方留下评论。 + + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/change-password-ubuntu + +作者：[Abhishek Prakash][a] +选题：[lujun9972][b] +译者：[An-DJ](https://github.com/An-DJ) +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://www.ubuntu.com/ +[2]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/change-password-ubuntu-linux.png?resize=800%2C450&ssl=1 +[3]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/change-user-password-linux-1.jpg?resize=800%2C253&ssl=1 +[4]: https://itsfoss.com/how-to-hack-ubuntu-password/ +[5]: https://itsfoss.com/install-ubuntu-1404-dual-boot-mode-windows-8-81-uefi/ +[6]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/02/change-user-password-ubuntu-gui-2.jpg?resize=800%2C484&ssl=1 +[7]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/change-user-password-ubuntu-gui-3.jpg?resize=800%2C488&ssl=1 +[8]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/change-user-password-ubuntu-gui-4.jpg?resize=800%2C555&ssl=1 +[9]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/change-user-password-ubuntu-gui-1.jpg?ssl=1 +[10]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/change-password-ubuntu-linux.png?fit=800%2C450&ssl=1 diff --git a/translated/tech/20190219 Logical - in Bash.md b/translated/tech/20190219 Logical - in Bash.md new file mode 100644 index 0000000000..1b69e80e00 --- /dev/null +++ b/translated/tech/20190219 Logical - in Bash.md @@ -0,0 +1,229 @@ +[#]: collector: "lujun9972" +[#]: translator: "zero-mk" +[#]: reviewer: " " +[#]: publisher: " " +[#]: url: " " +[#]: subject: "Logical & in Bash" +[#]: via: "https://www.linux.com/blog/learn/2019/2/logical-ampersand-bash" +[#]: author: "Paul Brown https://www.linux.com/users/bro66" + +Bash中的逻辑和（`&`） +====== + + + +有人可能会认为两篇文章中的`&`意思差不多，但实际上并不是。虽然 [第一篇文章讨论了如何在命令末尾使用`&`来将命令转到后台运行][1] 之后分解为解释流程管理， 第二篇文章将 [`&` 看作引用文件描述符的方法][2], 这些文章让我们知道了，与 `<` 和 `>` 结合使用后，你可以将输入或输出引导到别的地方。 + +但我们还没接触过作为 AND 操作符使用的`&`。所以，让我们来看看。 + +### & 是一个按位运算符 + +如果您完全熟悉二进制数操作，您肯定听说过 AND 和 OR 。这些是按位操作，对二进制数的各个位进行操作。在 Bash 中，使用`&`作为AND运算符，使用`|`作为 OR 运算符： + +**AND** + +``` +0 & 0 = 0 + +0 & 1 = 0 + +1 & 0 = 0 + +1 & 1 = 1 +``` + +**OR** + +``` +0 | 0 = 0 + +0 | 1 = 1 + +1 | 0 = 1 + +1 | 1 = 1 + +``` + + +您可以通过对任何两个数字进行 AND 运算并使用`echo`输出结果： + +``` +$ echo $(( 2 & 3 )) # 00000010 AND 00000011 = 00000010 + +2 + +$ echo $(( 120 & 97 )) # 01111000 AND 01100001 = 01100000 + +96 +``` + +OR（`|`）也是如此： + +``` +$ echo $(( 2 | 3 )) # 00000010 OR 00000011 = 00000011 + +3 + +$ echo $(( 120 | 97 )) # 01111000 OR 01100001 = 01111001 + +121 +``` + + +关于这个不得不说的三件事： + +1. 使用`(( ... ))`告诉 Bash 双括号之间的内容是某种算术或逻辑运算。`(( 2 + 2 ))`, `(( 5 % 2 ))` (`%`是[求模][3]运算符）和`((( 5 % 2 ) + 1))`（等于3）一切都会奏效。 + + 2. [像变量一样][4], 使用`$`提取值，以便你可以使用它。 + 3. 空格并没有影响: `((2+3))` 将等价于 `(( 2+3 ))` 和 `(( 2 + 3 ))`。 + 4. Bash只能对整数进行操作. 试试这样做： `(( 5 / 2 ))` ，你会得到"2"；或者这样 `(( 2.5 & 7 ))` ，但会得到一个错误。然后，在按位操作中使用除整数之外的任何东西（这就是我们现在所讨论的）通常是你不应该做的事情。 + + + +**提示:** 如果您想看看十进制数字在二进制下会是什么样子，你可以使用 _bc_ ，这是一个大多数 Linux 发行版都预装了的命令行计算器。比如： + +``` +bc <<< "obase=2; 97" +``` + +这个操作将会把 `97`转换成十二进制（`obase` 中的 _o_ 代表 _output_ ，也即，_输出_）。 + +``` +bc <<< "ibase=2; 11001011" +``` +这个操作将会把 `11001011`转换成十进制（`ibase` 中的 _i_ 代表 _input_ ，也即，_输入_）。 + +### &&是一个逻辑运算符 + +虽然它使用与其按位表达相同的逻辑原理，但Bash的`&&`运算符只能呈现两个结果：1（“true”）和0（“false”）。对于Bash来说，任何不是0的数字都是“true”，任何等于0的数字都是“false”。什么也是false也不是数字： + +``` +$ echo $(( 4 && 5 )) # 两个非零数字, 两个为true = true + +1 + +$ echo $(( 0 && 5 )) # 有一个为零, 一个为false = false + +0 + +$ echo $(( b && 5 )) # 其中一个不是数字, 一个为false = false + +0 +``` + +与 `&&` 类似， OR 对应着 `||` ，用法正如你想的那样。 + +以上这些都很简单... 直到进入命令的退出状态。 + +### &&是命令退出状态的逻辑运算符 + +[正如我们在之前的文章中看到的][2],当命令运行时，它会输出错误消息。更重要的是，对于今天的讨论，它在结束时也会输出一个数字。此数字称为_exit code_（即_返回码_），如果为0，则表示该命令在执行期间未遇到任何问题。如果是任何其他数字，即使命令完成，也意味着某些地方出错了。 +所以 0 意味着非常棒，任何其他数字都说明有问题发生，并且，在返回码的上下文中，0 意味着“真”，其他任何数字都意味着“假”。对！这 **与您所熟知的逻辑操作完全相反** ，但是你能用这个做什么？ 不同的背景，不同的规则。这种用处很快就会显现出来。 + +让我们继续！ + +返回码 _临时_ 储存在 [特殊变量][5] `?` 中— 是的，我知道：这又是一个令人迷惑的选择。但不管怎样, [别忘了我们在讨论变量的文章中说过][4], 那时我们说你要用 `$` 符号来读取变量中的值，在这里也一样。所以，如果你想知道一个命令是否顺利运行，你需要在命令结束后，在运行别的命令之前马上用 `$?` 来读取 `?` 的值。 + +试试下面的命令： + +``` +$ find /etc -iname "*.service" + +find: '/etc/audisp/plugins.d': Permission denied + +/etc/systemd/system/dbus-org.freedesktop.nm-dispatcher.service + +/etc/systemd/system/dbus-org.freedesktop.ModemManager1.service + +[等等内容] +``` + +[正如你在上一篇文章中看到的一样][2]，普通用户权限在 _/etc_ 下运行 `find` 通常将抛出错误，因为它试图读取你没有权限访问的子目录。 + +所以，如果你在执行 `find` 后立马执行... + +``` +echo $? +``` + +...，，它将打印 `1`，表明存在错误。 + +注意：当你在一行中运行两遍 `echo $?` ，你将得到一个 `0` 。这是因为 `$?` 将包含 `echo $?` 的返回码，而这条命令按理说一定会执行成功。所以学习如何使用 `$?` 的第一课就是： **单独执行 `$?`** 或者将它保存在别的安全的地方 —— 比如保存在一个变量里，不然你会很快丢失它。） + +一个直接使用 `?` 的用法是将它并入一串链式命令列表，这样 Bash 运行这串命令时若有任何操作失败，后面命令将终止。例如，您可能熟悉构建和编译应用程序源代码的过程。你可以像这样手动一个接一个地运行它们： + +``` +$ configure + +. + +. + +. + +$ make + +. + +. + +. + +$ make install + +. + +. + +. +``` + +你也可以把这三行合并成一行... + +``` +$ configure; make; make install +``` + +... 但你要希望上天保佑。 + +为什么这样说呢？因为你这样做是有缺点的，比方说 `configure` 执行失败了， Bash 将仍会尝试执行 `make` 和 `sudo make install`——就算没东西可 make ，实际上，是没东西会安装。 + +聪明一点的做法是： + +``` +$ configure && make && make install +``` + +这将从每个命令中获取退出代码，并将其用作链式 `&&` 操作的操作数。 +但是，没什么好抱怨的，Bash 知道如果 `configure` 返回非零结果，整个过程都会失败。如果发生这种情况，不必运行 `make` 来检查它的退出代码，因为无论如何都会失败的。因此，它放弃运行 `make` ，只是将非零结果传递给下一步操作。并且，由于 `configure && make` 传递了错误，Bash 也不必运行`make install`。这意味着，在一长串命令中，您可以使用 `&&` 连接它们，并且一旦失败，您可以节省时间，因为其他命令会立即被取消运行。 + +你可以类似地使用 `||`，OR 逻辑操作符，这样就算只有一部分命令成功执行，Bash 也能运行接下来链接在一起的命令。 +鉴于所有这些（以及我们之前介绍过的内容），您现在应该更清楚地了解我们在 [本文开头][1] 开头设置的命令行： + +``` +mkdir test_dir 2>/dev/null || touch backup/dir/images.txt && find . -iname "*jpg" > backup/dir/images.txt & +``` + +因此，假设您从具有读写权限的目录运行上述内容，它做了什么以及如何做到这一点？它如何避免不合时宜且可能导致执行错误的错误？下周，除了给你这些答案的结果，我们将讨论 brackets: curly, curvy and straight. 不要错过了哟！ + +因此，假设您在具有读写权限的目录运行上述内容，它会执行的操作以及如何执行此操作？它如何避免不合时宜且可能导致执行错误的错误？下周，除了给你解决方案，我们将处理包括：卷曲，曲线和直线。不要错过！ + +-------------------------------------------------------------------------------- + +via: https://www.linux.com/blog/learn/2019/2/logical-ampersand-bash + +作者：[Paul Brown][a] +选题：[lujun9972][b] +译者：[zero-MK](https://github.com/zero-mk) +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/2019/2/and-ampersand-and-linux +[2]: https://www.linux.com/blog/learn/2019/2/ampersands-and-file-descriptors-bash +[3]: https://en.wikipedia.org/wiki/Modulo_operation +[4]: https://www.linux.com/blog/learn/2018/12/bash-variables-environmental-and-otherwise +[5]: https://www.gnu.org/software/bash/manual/html_node/Special-Parameters.html diff --git a/中文排版指北.md b/中文排版指北.md deleted file mode 100644 index 9888b4dbc1..0000000000 --- a/中文排版指北.md +++ /dev/null @@ -1,294 +0,0 @@ -# 中文文案排版指北 -[](https://david-dm.org/mzlogin/chinese-copywriting-guidelines#info=devDependencies) - -统一中文文案、排版的相关用法，降低团队成员之间的沟通成本，增强网站气质。 - -Other languages: - -- [English](https://github.com/mzlogin/chinese-copywriting-guidelines/blob/Simplified/README.en.md) -- [Chinese Traditional](https://github.com/sparanoid/chinese-copywriting-guidelines) -- [Chinese Simplified](README.md) - ------ - -## 目录 - -- [空格](#空格) - - [中英文之间需要增加空格](#中英文之间需要增加空格) - - [中文与数字之间需要增加空格](#中文与数字之间需要增加空格) - - [数字与单位之间需要增加空格](#数字与单位之间需要增加空格) - - [全角标点与其他字符之间不加空格](#全角标点与其他字符之间不加空格) - - [`-ms-text-autospace` to the rescue?](#-ms-text-autospace-to-the-rescue) -- [标点符号](#标点符号) - - [不重复使用标点符号](#不重复使用标点符号) -- [全角和半角](#全角和半角) - - [使用全角中文标点](#使用全角中文标点) - - [数字使用半角字符](#数字使用半角字符) - - [遇到完整的英文整句、特殊名词，其內容使用半角标点](#遇到完整的英文整句特殊名词其內容使用半角标点) -- [名词](#名词) - - [专有名词使用正确的大小写](#专有名词使用正确的大小写) - - [不要使用不地道的缩写](#不要使用不地道的缩写) -- [争议](#争议) - - [链接之间增加空格](#链接之间增加空格) - - [简体中文不要使用直角引号](#简体中文不要使用直角引号) -- [工具](#工具) -- [谁在这样做？](#谁在这样做) -- [参考文献](#参考文献) - -## 空格 - -「有研究显示，打字的时候不喜欢在中文和英文之间加空格的人，感情路都走得很辛苦，有七成的比例会在 34 岁的时候跟自己不爱的人结婚，而其余三成的人最后只能把遗产留给自己的猫。毕竟爱情跟书写都需要适时地留白。 - -与大家共勉之。」——[vinta/paranoid-auto-spacing](https://github.com/vinta/pangu.js) - -### 中英文之间需要增加空格 - -正确： - -> 在 LeanCloud 上，数据存储是围绕 `AVObject` 进行的。 - -错误： - -> 在LeanCloud上，数据存储是围绕`AVObject`进行的。 - -> 在 LeanCloud上，数据存储是围绕`AVObject` 进行的。 - -完整的正确用法： - -> 在 LeanCloud 上，数据存储是围绕 `AVObject` 进行的。每个 `AVObject` 都包含了与 JSON 兼容的 key-value 对应的数据。数据是 schema-free 的，你不需要在每个 `AVObject` 上提前指定存在哪些键，只要直接设定对应的 key-value 即可。 - -例外：「豆瓣FM」等产品名词，按照官方所定义的格式书写。 - -### 中文与数字之间需要增加空格 - -正确： - -> 今天出去买菜花了 5000 元。 - -错误： - -> 今天出去买菜花了 5000元。 - -> 今天出去买菜花了5000元。 - -### 数字与单位之间需要增加空格 - -正确： - -> 我家的光纤入户宽带有 10 Gbps，SSD 一共有 20 TB。 - -错误： - -> 我家的光纤入户宽带有 10Gbps，SSD 一共有 10TB。 - -例外：度／百分比与数字之间不需要增加空格： - -正确： - -> 今天是 233° 的高温。 - -> 新 MacBook Pro 有 15% 的 CPU 性能提升。 - -错误： - -> 今天是 233 ° 的高温。 - -> 新 MacBook Pro 有 15 % 的 CPU 性能提升。 - -### 全角标点与其他字符之间不加空格 - -正确： - -> 刚刚买了一部 iPhone，好开心！ - -错误： - -> 刚刚买了一部 iPhone ，好开心！ - -### `-ms-text-autospace` to the rescue? - -Microsoft 有个 [`-ms-text-autospace`](http://msdn.microsoft.com/en-us/library/ie/ms531164(v=vs.85).aspx) 的 CSS 属性可以实现自动为中英文之间增加空白。不过目前并未普及，另外在其他应用场景，例如 OS X、iOS 的用户界面目前并不存在这个特性，所以请继续保持随手加空格的习惯。 - -## 标点符号 - -### 不重复使用标点符号 - -正确： - -> 德国队竟然战胜了巴西队！ - -> 她竟然对你说“喵”？！ - -错误： - -> 德国队竟然战胜了巴西队！！ - -> 德国队竟然战胜了巴西队！！！！！！！！ - -> 她竟然对你说「喵」？？！！ - -> 她竟然对你说「喵」？！？！？？！！ - -## 全角和半角 - -不明白什么是全角（全形）与半角（半形）符号？请查看维基百科词条『[全角和半角](http://zh.wikipedia.org/wiki/%E5%85%A8%E5%BD%A2%E5%92%8C%E5%8D%8A%E5%BD%A2)』。 - -### 使用全角中文标点 - -正确： - -> 嗨！你知道嘛？今天前台的小妹跟我说“喵”了哎！ - -> 核磁共振成像（NMRI）是什么原理都不知道？JFGI！ - -错误： - -> 嗨! 你知道嘛? 今天前台的小妹跟我说 "喵" 了哎! - -> 嗨!你知道嘛?今天前台的小妹跟我说"喵"了哎! - -> 核磁共振成像 (NMRI) 是什么原理都不知道? JFGI! - -> 核磁共振成像(NMRI)是什么原理都不知道?JFGI! - -### 数字使用半角字符 - -正确： - -> 这件蛋糕只卖 1000 元。 - -错误： - -> 这件蛋糕只卖 １０００ 元。 - -例外：在设计稿、宣传海报中如出现极少量数字的情形时，为方便文字对齐，是可以使用全角数字的。 - -### 遇到完整的英文整句、特殊名词，其內容使用半角标点 - -正确： - -> 乔布斯那句话是怎么说的？“Stay hungry, stay foolish.” - -> 推荐你阅读《Hackers & Painters: Big Ideas from the Computer Age》，非常的有趣。 - -错误： - -> 乔布斯那句话是怎么说的？「Stay hungry，stay foolish。」 - -> 推荐你阅读《Hackers＆Painters：Big Ideas from the Computer Age》，非常的有趣。 - -## 名词 - -### 专有名词使用正确的大小写 - -大小写相关用法原属于英文书写范畴，不属于本 wiki 讨论內容，在这里只对部分易错用法进行简述。 - -正确： - -> 使用 GitHub 登录 - -> 我们的客户有 GitHub、Foursquare、Microsoft Corporation、Google、Facebook, Inc.。 - -错误： - -> 使用 github 登录 - -> 使用 GITHUB 登录 - -> 使用 Github 登录 - -> 使用 gitHub 登录 - -> 使用 gｲんĤЦ8 登录 - -> 我们的客户有 github、foursquare、microsoft corporation、google、facebook, inc.。 - -> 我们的客户有 GITHUB、FOURSQUARE、MICROSOFT CORPORATION、GOOGLE、FACEBOOK, INC.。 - -> 我们的客户有 Github、FourSquare、MicroSoft Corporation、Google、FaceBook, Inc.。 - -> 我们的客户有 gitHub、fourSquare、microSoft Corporation、google、faceBook, Inc.。 - -> 我们的客户有 gｲんĤЦ8、ｷouЯƧquﾑгє、๓เςг๏ร๏Ŧt ς๏гק๏гคtเ๏ภn、900913、ƒ4ᄃëв๏๏к, IПᄃ.。 - -注意：当网页中需要配合整体视觉风格而出现全部大写／小写的情形，HTML 中请使用标准的大小写规范进行书写；并通过 `text-transform: uppercase;`／`text-transform: lowercase;` 对表现形式进行定义。 - -### 不要使用不地道的缩写 - -正确： - -> 我们需要一位熟悉 JavaScript、HTML5，至少理解一种框架（如 Backbone.js、AngularJS、React 等）的前端开发者。 - -错误： - -> 我们需要一位熟悉 Js、h5，至少理解一种框架（如 backbone、angular、RJS 等）的 FED。 - -## 争议 - -以下用法略带有个人色彩，既：无论是否遵循下述规则，从语法的角度来讲都是**正确**的。 - -### 链接之间增加空格 - -用法： - -> 请 [提交一个 issue](#) 并分配给相关同事。 - -> 访问我们网站的最新动态，请 [点击这里](#) 进行订阅！ - -对比用法： - -> 请[提交一个 issue](#) 并分配给相关同事。 - -> 访问我们网站的最新动态，请[点击这里](#)进行订阅！ - -### 简体中文不要使用直角引号 - -不管中英文，如果没有特殊要求，**不要用直角引号**。 - -## 工具 - -仓库 | 语言 ---- | --- -[vinta/paranoid-auto-spacing](https://github.com/vinta/paranoid-auto-spacing) | JavaScript -[huei90/pangu.node](https://github.com/huei90/pangu.node) | Node.js -[huacnlee/auto-correct](https://github.com/huacnlee/auto-correct) | Ruby -[sparanoid/space-lover](https://github.com/sparanoid/space-lover) | PHP (WordPress) -[nauxliu/auto-correct](https://github.com/NauxLiu/auto-correct) | PHP -[hotoo/pangu.vim](https://github.com/hotoo/pangu.vim) | Vim -[sparanoid/grunt-auto-spacing](https://github.com/sparanoid/grunt-auto-spacing) | Node.js (Grunt) -[hjiang/scripts/add-space-between-latin-and-cjk](https://github.com/hjiang/scripts/blob/master/add-space-between-latin-and-cjk) | Python - -## 谁在这样做？ - -网站 | 文案 | UGC ---- | --- | --- -[Apple 中国](http://www.apple.com/cn/) | Yes | N/A -[Apple 香港](http://www.apple.com/hk/) | Yes | N/A -[Apple 台湾](http://www.apple.com/tw/) | Yes | N/A -[Microsoft 中国](http://www.microsoft.com/zh-cn/) | Yes | N/A -[Microsoft 香港](http://www.microsoft.com/zh-hk/) | Yes | N/A -[Microsoft 台湾](http://www.microsoft.com/zh-tw/) | Yes | N/A -[LeanCloud](https://leancloud.cn/) | Yes | N/A -[知乎](https://www.zhihu.com/) | Yes | 部分用户达成 -[V2EX](https://www.v2ex.com/) | Yes | Yes -[SegmentFault](https://segmentfault.com/) | Yes | 部分用户达成 -[Apple4us](http://apple4us.com/) | Yes | N/A -[豌豆荚](https://www.wandoujia.com/) | Yes | N/A -[Ruby China](https://ruby-china.org/) | Yes | 标题达成 -[PHPHub](https://phphub.org/) | Yes | 标题达成 - -## 参考文献 - -- [Guidelines for Using Capital Letters](http://grammar.about.com/od/punctuationandmechanics/a/Guidelines-For-Using-Capital-Letters.htm) -- [Letter case - Wikipedia](http://en.wikipedia.org/wiki/Letter_case) -- [Punctuation - Oxford Dictionaries](http://www.oxforddictionaries.com/words/punctuation) -- [Punctuation - The Purdue OWL](https://owl.english.purdue.edu/owl/section/1/6/) -- [How to Use English Punctuation Corrently - wikiHow](http://www.wikihow.com/Use-English-Punctuation-Correctly) -- [格式 - openSUSE](https://zh.opensuse.org/index.php?title=Help:%E6%A0%BC%E5%BC%8F) -- [全角和半角 - 维基百科](http://zh.wikipedia.org/wiki/%E5%85%A8%E5%BD%A2%E5%92%8C%E5%8D%8A%E5%BD%A2) -- [引号 - 维基百科](http://zh.wikipedia.org/wiki/%E5%BC%95%E8%99%9F) -- [疑问惊叹号 - 维基百科](http://zh.wikipedia.org/wiki/%E7%96%91%E5%95%8F%E9%A9%9A%E5%98%86%E8%99%9F) - -## CopyRight - -[中文文案排版指北](https://github.com/sparanoid/chinese-copywriting-guidelines) diff --git a/选题模板.txt b/选题模板.txt deleted file mode 100644 index a7cd92e614..0000000000 --- a/选题模板.txt +++ /dev/null @@ -1,43 +0,0 @@ -选题标题格式: - - 原文日期 标题.md - -正文内容: - - 标题 - ======= - - ### 子一级标题 - - 正文 - - #### 子二级标题 - - 正文内容 - -  - - ### 子一级标题 - - 正文内容 ： I have a [dream][1]。 - - -------------------------------------------------------------------------------- - - via: 原文地址 - - 作者：[作者名][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]: 作者介绍地址 - [1]: 引文链接地址 - -说明: -1. 标题层级很多时从 “##” 开始 -2. 引文链接地址在下方集中写 -3. 因为 Windows 系统文件名有限制，所以文章名不要有特殊符号，如 `\/:*"<>|`，同时也不推荐全大写，或者其它不利阅读的格式 -4. 正文格式参照中文排版指北(https://github.com/LCTT/TranslateProject/blob/master/%E4%B8%AD%E6%96%87%E6%8E%92%E7%89%88%E6%8C%87%E5%8C%97.md) -5. 我们使用的 markdown 语法和 github 一致，具体语法可参见 https://github.com/guodongxiaren/README 。而实际中使用的都是基本语法，比如链接、包含图片、标题、列表、字体控制和代码高亮。 -6. 选题的内容分为两类： 干货和湿货。干货就是技术文章，比如针对某种技术、工具的介绍、讲解和讨论。湿货则是和技术、开发、计算机文化有关的文章。选题时主要就是根据这两条来选择文章，文章需要对大家有益处，篇幅不宜太短，可以是系列文章，也可以是长篇大论，但是文章要有内容，不能有严重的错误，最好不要选择已经有翻译的原文。
- ` 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
+ * `
- `、`