diff --git a/translated/tech/20181009 How To Create And Maintain Your Own Man Pages.md b/published/20181009 How To Create And Maintain Your Own Man Pages.md similarity index 56% rename from translated/tech/20181009 How To Create And Maintain Your Own Man Pages.md rename to published/20181009 How To Create And Maintain Your Own Man Pages.md index 407ad90947..4033be78b4 100644 --- a/translated/tech/20181009 How To Create And Maintain Your Own Man Pages.md +++ b/published/20181009 How To Create And Maintain Your Own Man Pages.md @@ -1,24 +1,25 @@ -如何创建和维护你的Man手册 +如何创建和维护你自己的 man 手册 ====== ![](https://www.ostechnix.com/wp-content/uploads/2018/10/Um-pages-1-720x340.png) -我们已经讨论了一些[Man手册的替代方案] [1]。 这些替代方案主要用于学习简洁的Linux命令示例，而无需通过全面过于详细的手册页。 如果你正在寻找一种快速而简单的方法来轻松快速地学习Linux命令，那么这些替代方案值得尝试。 现在，你可能正在考虑 - 如何为Linux命令创建自己的man-like帮助页面？ 这时**“Um”**就派上用场了。 Um是一个命令行实用程序，用于轻松创建和维护包含你到目前为止所了解的所有命令的Man页面。 +我们已经讨论了一些 [man 手册的替代方案][1]。 这些替代方案主要用于学习简洁的 Linux 命令示例，而无需通过全面而过于详细的手册页。 如果你正在寻找一种快速而简单的方法来轻松快速地学习 Linux 命令，那么这些替代方案值得尝试。 现在，你可能正在考虑 —— 如何为 Linux 命令创建自己的 man 式的帮助页面？ 这时 “Um” 就派上用场了。 Um 是一个命令行实用程序，可以用于轻松创建和维护包含你到目前为止所了解的所有命令的 man 页面。 -通过创建自己的手册页，你可以在手册页中避免大量不必要的细节，并且只包含你需要记住的内容。 如果你想创建自己的一套man-like页面，“Um”也能为你提供帮助。 在这个简短的教程中，我们将学习如何安装“Um”命令以及如何创建自己的man手册页。 +通过创建自己的手册页，你可以在手册页中避免大量不必要的细节，并且只包含你需要记住的内容。 如果你想创建自己的一套 man 式的页面，“Um” 也能为你提供帮助。 在这个简短的教程中，我们将学习如何安装 “Um” 命令以及如何创建自己的 man 手册页。 ### 安装 Um -Um适用于Linux和Mac OS。 目前，它只能在Linux系统中使用** Linuxbrew **软件包管理器来进行安装。 如果你尚未安装Linuxbrew，请参考以下链接。 +Um 适用于 Linux 和Mac OS。 目前，它只能在 Linux 系统中使用 Linuxbrew 软件包管理器来进行安装。 如果你尚未安装 Linuxbrew，请参考以下链接： -安装Linuxbrew后，运行以下命令安装Um实用程序。 +- [Linuxbrew：一个用于 Linux 和 MacOS 的通用包管理器][3] + +安装 Linuxbrew 后，运行以下命令安装 Um 实用程序。 ``` $ brew install sinclairtarget/wst/um - ``` -如果你会看到类似下面的输出，恭喜你！ Um已经安装好并且可以使用了。 +如果你会看到类似下面的输出，恭喜你！ Um 已经安装好并且可以使用了。 ``` [...] @@ -49,88 +50,78 @@ Emacs Lisp files have been installed to: ==> um Bash completion has been installed to: /home/linuxbrew/.linuxbrew/etc/bash_completion.d - ``` -在制作你的man手册页之前，你需要为Um启用bash补全。 +在制作你的 man 手册页之前，你需要为 Um 启用 bash 补全。 -要开启bash'补全，首先你需要打开 **~/.bash_profile** 文件: +要开启 bash 补全，首先你需要打开 `~/.bash_profile` 文件: ``` $ nano ~/.bash_profile - ``` -并在其中添加以下内容: +并在其中添加以下内容： ``` if [ -f $(brew --prefix)/etc/bash_completion.d/um-completion.sh ]; then . $(brew --prefix)/etc/bash_completion.d/um-completion.sh fi - ``` 保存并关闭文件。运行以下命令以更新更改。 ``` $ source ~/.bash_profile - ``` -准备工作全部完成。让我们继续创建我们的第一个man手册页。 +准备工作全部完成。让我们继续创建我们的第一个 man 手册页。 +### 创建并维护自己的man手册 -### 创建并维护自己的Man手册 - -如果你想为“dpkg”命令创建自己的Man手册。请运行: +如果你想为 `dpkg` 命令创建自己的 man 手册。请运行: ``` $ um edit dpkg - ``` -上面的命令将在默认编辑器中打开markdown模板： +上面的命令将在默认编辑器中打开 markdown 模板： ![](https://www.ostechnix.com/wp-content/uploads/2018/10/Create-dpkg-man-page.png) -我的默认编辑器是Vi，因此上面的命令会在Vi编辑器中打开它。现在，开始在此模板中添加有关“dpkg”命令的所有内容。 +我的默认编辑器是 Vi，因此上面的命令会在 Vi 编辑器中打开它。现在，开始在此模板中添加有关 `dpkg` 命令的所有内容。 -下面是一个示例: +下面是一个示例： ![](https://www.ostechnix.com/wp-content/uploads/2018/10/Edit-dpkg-man-page.png) -正如你在上图的输出中看到的，我为dpkg命令添加了概要，描述和两个参数选项。 你可以在Man手册中添加你所需要的所有部分。不过你也要确保为每个部分提供了适当且易于理解的标题。 完成后，保存并退出文件（如果使用Vi编辑器，请按ESC键并键入：wq）。 +正如你在上图的输出中看到的，我为 `dpkg` 命令添加了概要，描述和两个参数选项。 你可以在 man 手册中添加你所需要的所有部分。不过你也要确保为每个部分提供了适当且易于理解的标题。 完成后，保存并退出文件（如果使用 Vi 编辑器，请按 `ESC` 键并键入`:wq`）。 -最后，使用以下命令查看新创建的Man手册页： +最后，使用以下命令查看新创建的 man 手册页： ``` $ um dpkg - ``` ![](http://www.ostechnix.com/wp-content/uploads/2018/10/View-dpkg-man-page.png) -如你所见，dpkg的Man手册页看起来与官方手册页完全相同。 如果要在手册页中编辑和/或添加更多详细信息，请再次运行相同的命令并添加更多详细信息。 +如你所见，`dpkg` 的 man 手册页看起来与官方手册页完全相同。 如果要在手册页中编辑和/或添加更多详细信息，请再次运行相同的命令并添加更多详细信息。 ``` $ um edit dpkg - ``` -要使用Um查看新创建的Man手册页列表，请运行： +要使用 Um 查看新创建的 man 手册页列表，请运行： ``` $ um list - ``` -所有手册页将保存在主目录中名为**`.um` **的目录下 +所有手册页将保存在主目录中名为 `.um` 的目录下 以防万一，如果你不想要某个特定页面，只需删除它，如下所示。 ``` $ um rm dpkg - ``` 要查看帮助部分和所有可用的常规选项，请运行： @@ -151,7 +142,6 @@ Subcommands: um topics List all topics. um (c)onfig [config key] Display configuration environment. um (h)elp [sub-command] Display this help message, or the help message for a sub-command. - ``` ### 配置 Um @@ -166,22 +156,18 @@ pager = less pages_directory = /home/sk/.um/pages default_topic = shell pages_ext = .md - ``` -在此文件中，你可以根据需要编辑和更改** pager **，** editor **，** default_topic **，** pages_directory **和** pages_ext **选项的值。 比如说，如果你想在** [Dropbox] [2] **文件夹中保存新创建的Um页面，只需更改/.um/umconfig**文件中** pages_directory **的值并将其更改为Dropbox文件夹即可。 +在此文件中，你可以根据需要编辑和更改 `pager`、`editor`、`default_topic`、`pages_directory` 和 `pages_ext` 选项的值。 比如说，如果你想在 [Dropbox][2] 文件夹中保存新创建的 Um 页面，只需更改 `~/.um/umconfig` 文件中 `pages_directory` 的值并将其更改为 Dropbox 文件夹即可。 ``` pages_directory = /Users/myusername/Dropbox/um - ``` 这就是全部内容，希望这些能对你有用，更多好的内容敬请关注！ 干杯！ - - -------------------------------------------------------------------------------- via: https://www.ostechnix.com/how-to-create-and-maintain-your-own-man-pages/ @@ -189,7 +175,7 @@ via: https://www.ostechnix.com/how-to-create-and-maintain-your-own-man-pages/ 作者：[SK][a] 选题：[lujun9972][b] 译者：[way-ww](https://github.com/way-ww) -校对：[校对者ID](https://github.com/校对者ID) +校对：[wxy](https://github.com/wxy) 本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 @@ -197,3 +183,4 @@ via: https://www.ostechnix.com/how-to-create-and-maintain-your-own-man-pages/ [b]: https://github.com/lujun9972 [1]: https://www.ostechnix.com/3-good-alternatives-man-pages-every-linux-user-know/ [2]: https://www.ostechnix.com/install-dropbox-in-ubuntu-18-04-lts-desktop/ +[3]: https://www.ostechnix.com/linuxbrew-common-package-manager-linux-mac-os-x/ diff --git a/sources/talk/20180930 Creator of the World Wide Web is Creating a New Decentralized Web.md b/sources/talk/20180930 Creator of the World Wide Web is Creating a New Decentralized Web.md index df8804cbac..fb2916e06c 100644 --- a/sources/talk/20180930 Creator of the World Wide Web is Creating a New Decentralized Web.md +++ b/sources/talk/20180930 Creator of the World Wide Web is Creating a New Decentralized Web.md @@ -1,3 +1,5 @@ +translating by ypingcn + Creator of the World Wide Web is Creating a New Decentralized Web ====== **Creator of the world wide web, Tim Berners-Lee has unveiled his plans to create a new decentralized web where the data will be controlled by the users.** diff --git a/sources/talk/20181017 We already have nice things, and other reasons not to write in-house ops tools.md b/sources/talk/20181017 We already have nice things, and other reasons not to write in-house ops tools.md new file mode 100644 index 0000000000..e5502ed9bb --- /dev/null +++ b/sources/talk/20181017 We already have nice things, and other reasons not to write in-house ops tools.md @@ -0,0 +1,64 @@ +We already have nice things, and other reasons not to write in-house ops tools +====== +Let's look at the pitfalls of writing in-house ops tools, the circumstances that justify it, and how to do it better. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/tool-hammer-nail-build-broken.png?itok=91xn-5wI) + +When I was an ops consultant, I had the "great fortune" of seeing the dark underbelly of many companies in a relatively short period of time. Such fortune was exceptionally pronounced on one client engagement where I became the maintainer of an in-house deployment tool that had bloated to touch nearly every piece of infrastructure—despite lacking documentation and testing. Dismayed at the impossible task of maintaining this beast while tackling the real work of improving the product, I began reviewing my old client projects and probing my ops community for their strategies. What I found was an epidemic of "[not invented here][1]" (NIH) syndrome and a lack of collaboration with the broader community. + +### The problem with NIH + +One of the biggest problems of NIH is the time suck for engineers. Instead of working on functionality that adds value to the business, they're adding features to tools that solve standard problems such as deployment, continuous integration (CI), and configuration management. + +This is a serious issue at small or midsized startups, where new hires need to hit the ground running. If they have to learn a completely new toolset, rather than drawing from their experience with industry-standard tools, the time it takes them to become useful increases dramatically. While the new hires are learning the in-house tools, the company remains reliant on the handful of people who wrote the tools to document, train, and troubleshoot them. Heaven forbid one of those engineers succumbs to [the bus factor][2], because the possibility of getting outside help if they forgot to document something is zero. + +### Do you need to roll it yourself? + +Before writing your own ops tool, ask yourself the following questions: + + * Have we polled the greater ops community for solutions? + * Have we compared the costs of proprietary tools to the estimated engineering time needed to maintain an in-house solution? + * Have we identified open source solutions, even those that lack desired features, and attempted to contribute to them? + * Can we fork any open source tools that are well-written but unmaintained? + + + +If you still can't find a tool that meets your needs, you'll have to roll your own. + +### Tips for rolling your own + +Here's a checklist for rolling your own solutions: + + 1. In-house tooling should not be exempt from the high standards you apply to the rest of your code. Write it like you're going to open source it. + 2. Make sure you allow time in your sprints to work on feature requests, and don't allow features to be rushed in before proper testing and documentation. + 3. Keep it small. It's going to be much harder to exact any kind of exit strategy if your tool is a monstrosity that touches everything. + 4. Track your tool's usage and prune features that aren't actively utilized. + + + +### Have an exit strategy + +Open sourcing your in-house tool is not an exit strategy per se, but it may help you get outside contributors to free up your engineers' time. This is the more difficult strategy and will take some extra care and planning. Read "[Starting an Open Source Project][3]" and "[So You've Decided To Open-Source A Project At Work. What Now?][4]" before committing to this path. If you're interested in a cleaner exit, set aside time each quarter to research and test new open source replacements. + +Regardless of which path you choose, explicitly stating that an in-house solution is not the preferred state—early in its development—should clear up any confusion and prevent the issue of changing directions from becoming political. + +Sabice Arkenvirr will present [We Already Have Nice Things, Use Them!][5] at [LISA18][6], October 29-31 in Nashville, Tennessee, USA. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/10/nice-things + +作者：[Sabice Arkenvirr][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/vishuzdelishuz +[b]: https://github.com/lujun9972 +[1]: https://en.wikipedia.org/wiki/Not_invented_here +[2]: https://en.wikipedia.org/wiki/Bus_factor +[3]: https://opensource.guide/starting-a-project/ +[4]: https://www.smashingmagazine.com/2013/12/open-sourcing-projects-guide-getting-started/ +[5]: https://www.usenix.org/conference/lisa18/presentation/arkenvirr +[6]: https://www.usenix.org/conference/lisa18 diff --git a/sources/talk/20181018 Think global- How to overcome cultural communication challenges.md b/sources/talk/20181018 Think global- How to overcome cultural communication challenges.md new file mode 100644 index 0000000000..1d36d5e88d --- /dev/null +++ b/sources/talk/20181018 Think global- How to overcome cultural communication challenges.md @@ -0,0 +1,93 @@ +Think global: How to overcome cultural communication challenges +====== +Use these tips to ensure that every member of your global development team feels involved and understood. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/people_remote_teams_world.png?itok=_9DCHEel) + +A few weeks ago, I witnessed an interesting interaction between two work colleagues—Jason, who is from the United States; and Raj, who was visiting from India. + +Raj typically calls into a daily standup meeting at 9:00am US Central Time from India, but since he was in the US, he and his teammates headed toward the scrum area for the meeting. Jason stopped Raj and said, “Raj, where are you going? Don’t you always call into the stand-up? It would feel strange if you don’t call in.” Raj responded, “Oh, is that so? No worries,” and headed back to his desk to call into the meeting. + +I went to Raj’s desk. “Hey, Raj, why aren’t you going to the daily standup?” Raj replied, “Jason asked me to call in.” Meanwhile, Jason was waiting for Raj to come to the standup. + +What happened here? Jason was obviously joking when he made the remark about Raj calling into the meeting. But how did Raj miss this? + +Jason’s statement was meant as a joke, but Raj took it literally. This was a clear example of a misunderstanding that occurred due to unfamiliarity with each other’s cultural context. + +I often encounter emails that end with “Please revert back to me.” At first, this phrase left me puzzled. I thought, "What changes do they want me to revert?" Finally, I figured out that “please revert” means “Please reply.” + +In his TED talk, “[Managing Cross Cultural Remote Teams,][1]” Ricardo Fernandez describes an interaction with a South African colleague who ended an IM conversation with “I’ll call you just now.” Ricardo went back to his office and waited for the call. After fifteen minutes, he called his colleague: “Weren’t you going to call me just now?” The colleague responded, “Yes, I was going to call you just now.” That's when Ricardo realized that to his South African colleague, the phrase “just now” meant “sometime in the future.” + +In today's workplace, our colleagues may not be located in the same office, city, or even country. A growing number of tech companies have a global workforce comprised of employees with varied experiences and perspectives. This diversity allows companies to compete in the rapidly evolving technological environment. + +But geographically dispersed teams can face challenges. Managing and maintaining high-performing development teams is difficult even when the members are co-located; when team members come from different backgrounds and locations, that makes it even harder. Communication can deteriorate, misunderstandings can happen, and teams may stop trusting each other—all of which can affect the success of the company. + +What factors can cause confusion in global communication? In her book, “[The Culture Map][2],” Erin Meyer presents eight scales into which all global cultures fit. We can use these scales to improve our relationships with international colleagues. She identifies the United States as a very low-context culture in the communication scale. In contrast, Japan is identified as a high-context culture. + +What does it mean to be a high- or low-context culture? In the United States, children learn to communicate explicitly: “Say what you mean; mean what you say” is a common principle of communication. On the other hand, Japanese children learn to communicate effectively by mastering the ability to “read the air.” That means they are able to read between the lines and pick up on social cues when communicating. + +Most Asian cultures follow the high-context style of communication. Not surprisingly, the United States, a young country composed of immigrants, follows a low-context culture: Since the people who immigrated to the United States came from different cultural backgrounds, they had no choice but to communicate explicitly and directly. + +### The three R’s + +How can we overcome challenges in cross-cultural communication? Americans communicating with Japanese colleagues, for example, should pay attention to the non-verbal cues, while Japanese communicating with Americans should prepare for more direct language. If you are facing a similar challenge, follow these three steps to communicate more effectively and improve relationships with your international colleagues. + +#### Recognize the differences in cultural context + +The first step toward effective cross-cultural communication is to recognize that there are differences. Start by increasing your awareness of other cultures. + +#### Respect the differences in cultural context + +Once you become aware that differences in cultural context can affect cross-cultural communication, the next step is to respect these differences. When you notice a different style of communication, learn to embrace the difference and actively listen to the other person’s point of view. + +#### Reconcile the differences in cultural context + +Merely recognizing and respecting cultural differences is not enough; you must also learn how to reconcile the cultural differences. Understanding and being empathetic towards the other culture will help you reconcile the differences and learn how to use them to better advance productivity. + +### 5 ways to improve communications for cultural context + +Over the years, I have incorporated various approaches, tips, and tricks to strengthen relationships among team members across the globe. These approaches have helped me overcome communication challenges with global colleagues. Here are a few examples: + +#### Always use video conferencing when communicating with global teammates + +Studies show that about 55% of communication is non-verbal. Body language offers many subtle cues that can help you decipher messages, and video conferencing enables geographically dispersed team members to see each other. Videoconferencing is my default choice when conducting remote meetings. + +#### Ensure that every team member gets an opportunity to share their thoughts and ideas + +Although I prefer to conduct meetings using video conferencing, this is not always possible. If video conferencing is not a common practice at your workplace, it might take some effort to get everyone comfortable with the concept. Start by encouraging everyone to participate in audio meetings. + +One of our remote team members, who frequently met with us in audio conferences, mentioned that she often wanted to share ideas and contribute to the meeting but since we couldn’t see her and she couldn’t see us, she had no idea when to start speaking. If you are using audio conferencing, one way to mitigate this is to ensure that every team member gets an opportunity to share their ideas. + +#### Learn from one another + +Leverage your international friends to learn about their cultural context. This will help you interact more effectively with colleagues from these countries. I have friends from South Asia and South America who have helped me better understand their cultures, and this knowledge has helped me professionally. + +For programmers, I recommend conducting code reviews with your global peers. This will help you understand how those from different cultures give and receive feedback, persuade others, and make technical decisions. + +#### Be empathetic + +Empathy is the key to strong relationships. The more you are able to put yourself in someone else's shoes, the better able you will be to gain trust and build long-lasting connections. Encourage “water-cooler” conversations among your global colleagues by allocating the first few minutes of each meeting for small talk. This offers the additional benefit of putting everyone in a more relaxed mindset. If you manage a global team, make sure every member feels included in the discussion. + +#### Meet your global colleagues in person + +The best way to build long-lasting relationships is to meet your team members in person. If your company can afford it, arrange for this to happen. Meeting colleagues with whom you have been working will likely strengthen your relationship with them. The companies I have worked for have a strong record of periodically sending US team members to other countries and global colleagues to the US office. + +Another way to bring teams together is to attend conferences. This not only creates educational and training opportunities, but you can also carve out some in-person team time. + +In today's increasingly global economy, it is becoming more important for companies to maintain a geographically diverse workforce to remain competitive. Although global teams can face communication challenges, it is possible to maintain a high-performing development team despite geographical and cultural differences. Share some of the techniques you use in the comments. + + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/10/think-global-communication-challenges + +作者：[Avindra Fernando][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/avindrafernando +[b]: https://github.com/lujun9972 +[1]: https://www.youtube.com/watch?v=QIoAkFpN8wQ +[2]: https://www.amazon.com/The-Culture-Map-Invisible-Boundaries/dp/1610392507 diff --git a/sources/tech/20180615 Complete Sed Command Guide [Explained with Practical Examples].md b/sources/tech/20180615 Complete Sed Command Guide [Explained with Practical Examples].md deleted file mode 100644 index d2c50b6029..0000000000 --- a/sources/tech/20180615 Complete Sed Command Guide [Explained with Practical Examples].md +++ /dev/null @@ -1,1030 +0,0 @@ -Translating by qhwdw -Complete Sed Command Guide [Explained with Practical Examples] -====== -In a previous article, I showed the [basic usage of Sed][1], the stream editor, on a practical use case. Today, be prepared to gain more insight about Sed as we will take an in-depth tour of the sed execution model. This will be also an opportunity to make an exhaustive review of all Sed commands and to dive into their details and subtleties. So, if you are ready, launch a terminal, [download the test files][2] and sit comfortably before your keyboard: we will start our exploration right now! - -### A little bit of theory on Sed - -![complete reference guide to sed commands][4] - -#### A first look at the sed execution model - -To truly understand Sed you must first understand the tool execution model. - -When processing data, Sed reads one line of input at a time and stores it into the so-called pattern space. All Sed’s transformations apply to the pattern space. Transformations are described by one-letter commands provided on the command line or in an external Sed script file. Most Sed commands can be preceded by an address, or an address range, to limit their scope. - -By default, Sed prints the content of the pattern space at the end of each processing cycle, that is, just before overwriting the pattern space with the next line of input. We can summarize that model like that: - - 1. Try to read the next input line into the pattern space - - 2. If the read was successful: - - 1. Apply in the script order all commands whose address matches the current input line - - 2. If sed was not launched in quiet mode (`-n`) print the content of the (potentially modified) pattern space - - 3. got back to 1. - - - - -Since the content of the pattern space is lost after each line is processed, it is not suitable for long-term storage. For that purpose, Sed has a second buffer, the hold space. Sed never clears, puts or gets data from the hold space unless you explicitly request it. We will investigate that more in depth later when studying the exchange, get and hold commands. - -#### The Sed abstract machine - -The model explained above is what you will see described in many Sed tutorials. Indeed, it is correct enough to understand the most basic Sed programs. But when you start digging into more advanced commands, you will see it is not sufficient. So let’s try to be a little bit more formal now. - -Actually, Sed can be viewed as implementing an [abstract machine][5] whose [state][6] is defined by three [buffers][7], two [registers][8], and two [flags][9]: - - * **three buffers** to store arbitrary length text. Yes: three! In the basic execution model we talked about the pattern- and hold-space, but Sed has a third buffer: the append queue. From the Sed script perspective, it is a write-only buffer that Sed will flush automatically at predefined moments of its execution (broadly speaking before reading a new line from the input, or just before quitting). - - * Sed also maintains **two registers** : the line counter (LC) which holds the number of lines read from the input, and the program counter (PC) which always hold the index (“position” in the script) of the next command to execute. Sed automatically increments the PC as part of its main loop. But using specific commands, a script can also directly modify the PC to skip or repeat parts of the program. This is how loops or conditional statements can be implemented with Sed. More on that in the dedicated branches section below. - - * Finally **two flags** can modify the behavior of certain Sed commands: the auto-print flag (AP) the substitution flag (SF). When the auto-print flag is set, Sed will automatically print the content of the pattern space before overwriting it (notably before reading a new line of input but not only). When the auto-print flag is clear (“not set”), Sed will never print the content of the pattern space without an explicit command in the script. You can clear the auto-print flag by running Sed in “quiet mode” (using the `-n` command line option or by using the special comment`#n` on the very first line or the script). The “substitution flag” is set by the substitution command (the `s` command) when both its address and search pattern match the content of the pattern space. The substitution flag is cleared at the start of each new cycle, or when a new line is read from input, or after a conditional branch is taken. Here again, we will revisit that topic in details in the branches section. - - - - -In addition, Sed maintains the list of commands having entered their address range (more on that of the range addresses section) as well as a couple of file handles to read and write data. You will find some more information on that in the read and write command description. - -#### A more accurate Sed execution model - -As a picture worth thousands of words, I draw a flowchart describing the Sed execution model. I left a couple of things aside, like dealing with multiple input files or error handling, but I think this should be sufficient for you to understand the behavior of any Sed program and to avoid wasting your time by groping around while writing your own Sed scripts. - -![The Sed execution model][10] - -You may have noticed I didn’t describe the command-specific actions in the flowchart above. We will see that in detail for each command. So, without further ado, let’s start our tour! - -### The print command - -The print command (`p`) displays the content of the pattern space at the moment it is executed. It does not change in any way the state of the Sed abstract machine. - -![The Sed `print` command][11] - -For example: -``` -sed -e 'p' inputfile - -``` - -The command above will print each line of the input file … twice. Once because you explicitly requested it using the `print` command, and a second time implicitly at the end of the processing loop (because we didn’t launch Sed in “quiet mode” here). - -If we are not interested in seeing each line twice, we have two way of fixing that: -``` -sed -n -e 'p' inputfile # quiet mode with explicit print -sed -e '' inputfile # empty "do nothing" program, implicit print - -``` - -Note: the `-e` option introduces a Sed command. It is used to distinguish between commands and file names. Since a Sed invocation must contain at least one command, the `-e` flag is optional for that first command. However, I have the habit of using it, mostly for consistency with more complex cases where I have to give multiple Sed expressions on the command line. I let you figure by yourself if this is a good or bad habit, but I will follow that convention in the rest of the article. - -### Addresses - -Obviously, the print command is not very useful by itself. However, if you add an address before the command to apply it only to some lines of the input file, it suddenly becomes able to filter out unwanted lines from a file. But what’s an address for Sed? And how are identified the “lines” of the input file? - -#### Line numbers - -A Sed address can be either a line number (with the extension of `$` to mean “the last line”) or a regular expression. When using line numbers, you have to remember lines are numbered starting from one in Sed— and not starting from zero. -``` -sed -n -e '1p' inputfile # print only the first line of the file -sed -n -e '5p' inputfile # print only the line 5 -sed -n -e '$p' inputfile # print the last line of the file -sed -n -e '0p' inputfile # will result in an error because 0 is not a valid line number - -``` - -According to the [POSIX specifications][12], line numbers are cumulative if you specify several input files. In other words, the line counter is not reset when Sed opens a new input file. So, the two commands below will do the same thing, printing only one line of text to the output: -``` -sed -n -e '1p' inputfile1 inputfile2 inputfile3 -cat inputfile1 inputfile2 inputfile3 | sed -n -e '1p' - -``` - -Actually, this is exactly how POSIX defines multiple file handling: - -> If multiple file operands are specified, the named files shall be read in the order specified and the concatenation shall be edited. - -However, some Sed implementations offer command line options to change that behavior, like the GNU Sed `-s` flag (which is implicitly applied too when using the GNU Sed `-i` flags): -``` -sed -sn -e '1p' inputfile1 inputfile2 inputfile3 - -``` - -If your implementation of Sed supports such non-standard options, I let you check into the `man` for the details regarding them. - -#### Regular expressions - -I’ve said Sed addresses could be line numbers or regular expressions. But what is this regex thing? - -In just a few words, a [regular expression][13] is a way to describe a set of strings. If a given string pertains to the set described by a regular expression, we said the string matches the regular expression. - -A regular expression may contain literal characters that must be present verbatim into a string to have a match. For example, all letters and digits behave that way, as well as most printable characters. However, some symbols have a special meaning: - - * They could represent anchors, like `^` and `$` that respectively denotes the start or end of a line; - - * other symbols can serve as placeholders for entire sets of characters (like the dot that matches any single characters or the square brackets that are used to define a custom character set); - - * others again are quantifiers that serve to denotes repetitions (like the [Kleene star][14] that means 0, 1 or several occurrences of the previous pattern). - - - - -My goal here is not to give you a regular expression tutorial. So I will stick with just a few examples. However, feel free to search for more on the web about that topic: regular expressions are a really powerful feature available in many standard Unix commands and programming language and a skill every Unixien should master. - -Here are few examples used in the context of a Sed address: -``` -sed -n -e '/systemd/p' inputfile # print only lines *containing* the literal string "systemd" -sed -n -e '/nologin$/p' inputfile # print only lines ending with "nologin" -sed -n -e '/^bin/p' inputfile # print only lines starting with "bin" -sed -n -e '/^$/p' inputfile # print only empty lines (i.e.: nothing between the start and end of a line) -sed -n -e '/./p' inputfile # print only lines containing a character (i.e. print only non-empty lines) -sed -n -e '/^.$/p' inputfile # print only lines containing exactly one character -sed -n -e '/admin.*false/p' inputfile # print only lines containing "admin" followed by "false" (with any number of arbitrary characters between them) -sed -n -e '/1[0,3]/p' inputfile # print only lines containing a "1" followed by a "0" or "3" -sed -n -e '/1[0-2]/p' inputfile # print only lines containing a "1" followed by a "0", "1", "2" or "3" -sed -n -e '/1.*2/p' inputfile # print only lines containing the character "1" followed by a "2" (with any number of arbitrary characters between them) -sed -n -e '/1[0-9]*2/p' inputfile # print only lines containing the character "1" followed by zero, one or more digits, followed by a "2" - -``` - -If you want to remove the special meaning of a character in a regular expression (including the regex delimiter symbol), you have to precede it with a slash: -``` -# Print all lines containing the string "/usr/sbin/nologin" -sed -ne '/\/usr\/sbin\/nologin/p' inputfile - -``` - -You are not limited to use only the slash as the regular expression delimiter in an address. You can use any other character that could suit your needs and tastes by preceding the first delimiter by a backslash. This is particularly useful when you have addresses that should match literal slashes like when working with file paths: -``` -# Both commands are perfectly identical -sed -ne '/\/usr\/sbin\/nologin/p' inputfile -sed -ne '\=/usr/sbin/nologin=p' inputfile - -``` - -#### Extended regular expressions - -By default, the Sed regular expression engine only understands the [POSIX basic regular expression][15] syntax. If you need [extended regular expressions][16], you must add the `-E` flag to the Sed command. Extended regular expressions add a couple of extra feature to basic regular expressions and, most important maybe, they require far fewer backslashes. I let you compare: -``` -sed -n -e '/\(www\)\|\(mail\)/p' inputfile -sed -En -e '/(www)|(mail)/p' inputfile - -``` - -#### The bracket quantifier - -One powerful feature of regular expressions is the [range quantifier][17]`{,}`. Actually, when written exactly like that, this quantifier is a perfect synonym for the `*` quantifier. However, you can explicitly add a lower and upper bound on each side of the coma, something that gives a tremendous amount of flexibility. When the lower bound of the range quantifier is omitted, it is assumed to be zero. When the upper bound is omitted, it is assumed to be the infinity: - -|Bracket notation| Shorthand |Description| - -| {,} | * | zero, one or many occurrences of the preceding regex | -| {,1} | ? | zero or one occurrence of the preceding regex | -| {1,} | + | one or many occurrences of the preceding regex | -| {n,n} | {n} | exactly n occurrences of the preceding regex | - -The bracket notation is available in basic regular expressions too, but it requires backslashes. According to POSIX, the only quantifiers available in basic regular expression are the star and the bracket notation (with backslashes `\{m,n\}`). Many regex engines do support the `\?` and `\+` notation as an extension. However, why tempting the devil? If you need those quantifiers, using extended regular expressions will be both easier to write and more portable. - -If I took the time to talk about the bracket notation for regex quantifiers, this is because that feature is often useful in Sed scripts to count characters. -``` -sed -En -e '/^.{35}$/p' inputfile # Print lines containing exactly 35 characters -sed -En -e '/^.{0,35}$/p' inputfile # Print lines containing 35 characters or less -sed -En -e '/^.{,35}$/p' inputfile # Print lines containing 35 characters or less -sed -En -e '/^.{35,}$/p' inputfile # Print lines containing 35 characters or more -sed -En -e '/.{35}/p' inputfile # I let you figure out this one by yourself (test it!) - -``` - -#### Range addresses - -All the addresses we used so far were unique addresses. When using an unique address, the command is applied only the line(s) matching that address. However, Sed also supports range addresses. They are used to apply a command to all lines between the start and the end address of the range: -``` -sed -n -e '1,5p' inputfile # print only lines 1 through 5 -sed -n -e '5,$p' inputfile # print from line 5 to the end of the file - -sed -n -e '/www/,/systemd/p' inputfile # print from the first line matching the /www/ regular expression to the next line matching the /systemd/ regular expression. - -``` - -If the same line number is used both for the start and end address, the range is reduced to that line. Actually, if the second address is a number less than or equal to the line number of the first selected line of the range, only one line will be selected: -``` -printf "%s\n" {a,b,c}{d,e,f} | cat -n | sed -ne '4,4p' - 4 bd -printf "%s\n" {a,b,c}{d,e,f} | cat -n | sed -ne '4,3p' - 4 bd - -``` - -This is somewhat tricky, but the rule given in the previous paragraph also applies when the start address is a regular expression. In that case, Sed will compare the line number of the first line matching the regex with the explicit line number given as end address. Once again, if the end line number is lower or equal to the start line number, the range will be reduced to one line: -``` -# The /b/,4 address will match *three* one-line range -# since each matching line has a line number >= 4 -printf "%s\n" {a,b,c}{d,e,f} | cat -n | sed -ne '/b/,4p' - 4 bd - 5 be - 6 bf - -# I let you figure by yourself how many ranges are matched -# by that second example: -printf "%s\n" {a,b,c}{d,e,f} | cat -n | sed -ne '/d/,4p' - 1 ad - 2 ae - 3 af - 4 bd - 7 cd - -``` - -However, the behavior of Sed is different when the end address is a regular expression. In that case, the first line of the range is not tested against the end address, so the range will contain at least two lines (except of course if there is not enough input data): -``` -printf "%s\n" {a,b,c}{d,e,f} | cat -n | sed -ne '/b/,/d/p' - 4 bd - 5 be - 6 bf - 7 cd - -printf "%s\n" {a,b,c}{d,e,f} | cat -n | sed -ne '4,/d/p' - 4 bd - 5 be - 6 bf - 7 cd - -``` - -#### Complement - -Adding an exclamation mark (`!`) after an address select lines not matching that address. For example: -``` -sed -n -e '5!p' inputfile # Print all lines except line 5 -sed -n -e '5,10!p' inputfile # Print all lines except line 5 to 10 -sed -n -e '/sys/!p' inputfile # Print all lines except those containing "sys" - -``` - -#### Conjunctions - -Sed allows to group commands in blocks using brackets (`{…​}`). You can leverage that feature to combine several addresses. For example, let’s compare the output of those two commands: -``` -sed -n -e '/usb/{ -/daemon/p -}' inputfile - -sed -n -e '/usb.*daemon/p' inputfile - -``` - -By nesting commands in a block, we will select lines containing “usb” and “daemon” in any order. Whereas the regular expression “usb.*daemon” would only match lines where the “usb” string appears before the “daemon” string. - -After that long digression, let’s go back now to our review of the various Sed commands. - -### The quit command - -The quit command will stop Sed at the end of the current processing loop iteration. - -![The Sed `quit` command][18] - -The `quit` command is a way to stop input processing before reaching the end of the input file. Why would someone want to do that? - -Well, if you remember, we’ve seen you can print the lines 1 through 5 of a file using the following command: -``` -sed -n -e '1,5p' inputfile - -``` - -With most implementations of Sed, the tool will read and cycle over all the remaining input lines, even if only the first five can produce a result. This may have a significant impact if your file contains millions of rows (or even worst, if you read from an infinite stream of data like `/dev/urandom` for example). - -Using the quit command, the same program can be rewritten much more efficiently: -``` -sed -e '5q' inputfile - -``` - -Here, since I did not use the `-n` option, Sed will implicitly print the pattern space at the end of each cycle, but it will quit, and thus not reading more data, after having processed the line 5. - -We could use a similar trick to print only a specific line of a file. That will be a good occasion to see several ways of providing multiple Sed expressions from the command line. The three variations bellow take benefit of Sed accepting several commands, either as different `-e` options, or in the same expression, but separated by newlines or semi-colon: -``` -sed -n -e '5p' -e '5q' inputfile - -sed -n -e ' - 5p - 5q -' inputfile - -sed -n -e '5p;5q' inputfile - -``` - -If you remember it, we’ve seen earlier we can group commands using brackets, something that we could use here to avoid repeating the same address twice: -``` -# By grouping commands -sed -e '5{ - p - q -}' inputfile - -# Which can be shortened as: -sed '5{p;q;}' inputfile - -# As a POSIX extension, some implementations makes the semi-colon before the closing bracket optional: -sed '5{p;q}' inputfile - -``` - -### The substitution command - -You can imagine the substitution command as the Sed equivalent to the search-replace feature you can find on most WYSIWYG editors. An equivalent, albeit a more powerful one though. The substitution command being one of the best-known Sed commands, it is largely documented on the web. - -![The Sed `substitution` command][19] - -We already have covered it [in a previous article][20] so I will not repeat myself here. However there are some key points to remember if you’re not yet completely familiar with it: - - * The substitution command takes two parameters: the search pattern and the replacement string: `sed s/:/-----/ inputfile` - - * The command and its arguments are separated by an arbitrary character. Mostly by habit, 99% of the time we use a slash but any other character can be used: `sed s%:%-----% inputfile`, `sed sX:X-----X inputfile` or even `sed 's : ----- ' inputfile` - - * By default, the substitution is applied only to the first matching substring of the pattern space. You can change that by specifying the match index as a flag after the command: `sed 's/:/-----/1' inputfile`, `sed 's/:/-----/2' inputfile`, `sed 's/:/-----/3' inputfile`, … - - * If you want to perform a substitution globally (i.e.: on each non-overlapping match of the pattern space), you need to add the `g` flag: `sed 's/:/-----/g' inputfile` - - * In the replacement string, any occurrence of the ampersand (`&`) will be replaced by the substring matching the search pattern: `sed 's/:/-&&&-/g' inputfile`, `sed 's/…​./& /g' inputfile` - - * Parenthesis ( `(…​)` in extended regex or `\(…​\)` in basic regex) introduce a capturing group. That is a part of the matching string that can be referenced in the replacement string. `\1` is the content of the first capturing group, `\2` the content of the second one and so on: `sed -E 's/(.)(.)/\2\1/g' inputfile`, `sed -E 's/(.):x:(.):(.*)/\1:\3/' inputfile` (that latter works because [the star regular expression quantifier is greedy][21], and matches as many characters as it can) - - * In the search pattern or the replacement string you can remove the special meaning of any character by preceding it with a backslash: `sed 's/:/--\&--/g' inputfile`, `sed 's/\//\\/g' inputfile` - - - - -As all this might seem a little bit abstract, here are a couple of examples. To start, let’s say I want to display the first field of my test input file padded with spaces on the right up to 20 characters, I could write something like that: -``` -sed < inputfile -E -e ' - s/:/ / # replace the first field separator by 20 spaces - s/(.{20}).*/\1/ # keep only the first 20 characters of the line - s/.*/| & |/ # add vertical bars for a nice output -' - -``` - -As a second example, if I want to change the UID/GID of the user sonia to 1100, I could write something like that: -``` -sed -En -e ' - /sonia/{ - s/[0-9]+/1100/g - p - }' inputfile - -``` - -Notice the `g` option at the end of the substitution command. It modifies its behavior, so all occurrences of the search pattern are replaced. Without that option, only the first one would be. - -By the way, this is also a good occasion to mention the print command displays the content of the pattern space at the moment the command is executed. So, I can obtain a before-after output like that: -``` -sed -En -e ' - /sonia/{ - p - s/[0-9]+/1100/g - p - }' inputfile - -``` - -Actually, since printing a line after a substitution is a common use case, the substitution command also accepts the `p` option for that purpose: -``` -sed -En -e '/sonia/s/[0-9]+/1100/gp' inputfile - -``` - -Finally, I won’t be exhaustive without mentioning the `w` option of the substitution command. We will examine it in detail later. - -#### The delete command - -The delete command (`d`) is used to clear the pattern space and immediately start the next cycle. By doing so, it will also skip the implicit print of the pattern space even if the auto-print flag is set. - -![The Sed `delete` command][22] - -A particularly inefficient way of printing only the first five lines of a file would be: -``` -sed -e '6,$d' inputfile - -``` - -I let you guess why I said this was inefficient. If this is not obvious, try to re-read the section concerning the quit command. The answer is there! - -The delete command is particularly useful when combined with regular expression-based addresses to remove matching lines from the output: -``` -sed -e '/systemd/d' inputfile - -``` - -#### The next command - -This command prints the current pattern space if Sed is not running in quiet mode, then, in all cases, it reads the next input line into the pattern space and executes the remaining commands of the current cycle with the new pattern space. - -![The Sed `next` command][23] - -A common use case of the next command is to skip lines: -``` -cat -n inputfile | sed -n -e 'n;n;p' - -``` - -In the example above, Sed will implicitly read the first line of the input file. But the `next` command discards (and does not display because of the `-n` option) the pattern space and replaces it with the next line from the input. And the second `next` command will do the same thing, skipping now the line 2 of the input. And finally, the script explicitly prints the pattern space which now contains the third line of the input. Then Sed will start a new cycle, implicitly reading the line 4, then skipping it, as well as the line 5, because of the `next` commands, and it will print the line 6. And again and again until the end of the file. Concretely, this prints one line over three of the input file. - -Using the next command, we can also find a couple of other ways to display the first five lines of a file: -``` -cat -n inputfile | sed -n -e '1{p;n;p;n;p;n;p;n;p}' -cat -n inputfile | sed -n -e 'p;n;p;n;p;n;p;n;p;q' -cat -n inputfile | sed -e 'n;n;n;n;q' - -``` - -More interestingly, the next command is also very useful when you want to process lines relative to some address: -``` -cat -n inputfile | sed -n '/pulse/p' # print lines containing "pulse" -cat -n inputfile | sed -n '/pulse/{n;p}' # print the line following - # the line containing "pulse" -cat -n inputfile | sed -n '/pulse/{n;n;p}' # print the line following - # the line following - # the line containing "pulse" - -``` - -### Working with the hold space - -Until now, the command we’ve seen dealt only with the pattern space. However, as we’ve mentioned it at the very top of this article, there is a second buffer, the hold space, entirely under the control of the user. This will be the purpose of the commands described in this section. - -#### The exchange command - -As it names implies it, the exchange command (`x`) will swap the content of the hold and pattern space. Remember as long as you didn’t put anything into the hold space, it is empty. - -![The Sed `exchange` command][24] - -As a first example, we may use the exchange command to print in reverse order the first two lines of a file: -``` -cat -n inputfile | sed -n -e 'x;n;p;x;p;q' - -``` - -Of course, you don’t have to use the content of the hold space immediately after having set it, since the hold space remains untouched as long as you don’t explicitly modify it. In the following example, I use it to move the first line of the input after the fifth one: -``` -cat -n inputfile | sed -n -e ' - 1{x;n} # Swap the hold and pattern space - # to store line 1 into the hold buffer - # and then read line two - 5{ - p # print line 5 - x # swap the hold and pattern space to get - # back the content of line one into the - # pattern space - } - - 1,5p # triggered on lines 2 through 5 - # (not a typo! try to figure why this rule - # is NOT executed for line 1;) -' - -``` - -#### The hold commands - -The hold command (`h`) is used to store the content of the pattern space into the hold space. However, as opposed to the exchange command, this time the content of the pattern space is left unchanged. The hold commands came in two flavors: - - * `h` -that will copy the content of the pattern space into the hold space, overwriting any value already present - - * `H` -that will append the content of the pattern space to the hold space, using a newline as separator - - - - -![The Sed `hold` command][25] - -The example above using the exchange command can be rewritten using the hold command instead: -``` -cat -n inputfile | sed -n -e ' - 1{h;n} # Store line 1 into the hold buffer and continue - 5{ # on line 5 - x # switch the pattern and hold space - # (now the pattern space contains the line 1) - H # append the line 1 after the line 5 in the hold space - x # switch again to get back lines 5 and 1 into - # the pattern space - } - - 1,5p # triggered on lines 2 through 5 - # (not a typo! try to figure why this rule - # is NOT executed for line 1;) -' - -``` - -#### The get command - -The get command (`g`) does the exact opposite of the hold command: it takes the content of the hold space and put it into the pattern space. Here again, it comes in two flavors: - - * `g` -that will copy the content of the hold space into the pattern space, overwriting any value already present - - * `G` -that will append the content of the hold space to the pattern space, using a newline as separator - - - - -![The Sed `get` command][26] - -Together, the hold and get commands allow to store and recall data. As a little challenge, I let you rewrite the example of the previous section to put the line 1 of the input file after the line 5, but this time using the get and hold commands (lower- or upper-case version), but without using the exchange command. With a little bit of luck, it should be simpler that way! - -In the meantime, I can show you another example that could serve for your inspiration. The goal here is to separate the users having a login shell from the others: -``` -cat -n inputfile | sed -En -e ' - \=(/usr/sbin/nologin|/bin/false)$= { H;d; } - # Append matching lines to the hold buffer - # and continue to next cycle - p # Print other lines - $ { g;p } # On the last line, - # get and print the content of the hold buffer -' - -``` - -### print, delete and next revisited - -Now you’ve gained more familiarities with the hold space, let me go back on the `print`, `delete` and `next` commands. We already talked about the lower case `p`, `d` and `n` commands. But they also have an upper case version. As it seems to be a convention with Sed, the uppercase version of those commands will be related to multi-line buffers: - - * `P` -print the content of the pattern space up to the first newline - - * `D` -delete the content of the pattern space up and including the first newline then restart a cycle with the remaining text without reading any new input - - * `N` -read and append a new line of input to the pattern space using the newline character as a separator between the old and new data. Continue the execution of the current cycle. - - - - -![The Sed uppercase `Delete` command][27] -![The Sed uppercase `Next` command][28] - -The main use case for those commands is to implement queues ([FIFO lists][29]). The canonical example being removing the last 5 lines from a file: -``` -cat -n inputfile | sed -En -e ' - 1 { N;N;N;N } # ensure the pattern space contains *five* lines - - N # append a sixth line onto the queue - P # Print the head of the queue - D # Remove the head of the queue -' - -``` - -As a second example, we could display input data on two columns: -``` -# Print on two columns -sed < inputfile -En -e ' - $!N # Append a new line to the pattern space - # *except* on the last line of input - # This is a trick required to deal with - # inconsistencies between GNU Sed and POSIX Sed - # when using N on the last line of input - # https://www.gnu.org/software/sed/manual/sed.html#N_005fcommand_005flast_005fline - - # Right pad the first field of the first line - # with spaces and discard rest of the line - s/:.*\n/ \n/ - s/:.*// # Discard all but the first field on the second line - s/(.{20}).*\n/\1/ # Trim and join lines - p # Print result -' - -``` - -### Branching - -We just saw Sed has buffer capabilities through the hold space. But it also has test and branch instructions. Having both those features makes Sed a [Turing complete][30] language. It may sound silly, but that means you can write any program using Sed. You can do it, but that does not mean it would be an easy task, nor that the result would be particularly efficient of course. - -However, don’t panic. In this article, we will stay with simple examples of tests and branches. Even if these capabilities seem limited at first sight, remember some people have written [calculators], [Tetris] or many other kinds of applications using sed! - -#### labels and branches - -By some aspects, you can see Sed as a very limited assembly language. So you won’t find high-level “for” or “while” loops or “if … else” statements, but you can implement them using branches. - -![The Sed `branch` command][31] - -If you take a look at the flowchart describing the Sed execution model at the top of this article, you can see Sed automatically increments the program counter, resulting in the execution of the commands in the program’s instructions order. However, using branch instructions, you can break that sequential flow by continuing the execution with any command of your choice in the program. The destination of a jump is explicitly defined using a label. - -![The Sed `label` command][32] - -Here is an example: -``` -echo hello | sed -ne ' - :start # Put the "start" label on that line of the program - p # Print the pattern buffer - b start # Continue execution at the :start label -' | less - -``` - -The behavior of that Sed program is very close to the `yes` command: it takes a string and produces an infinite stream of lines containing that string. - -Branching to a label as we did bypass all Sed automatic features: it does not read any input, nor print anything, nor update any buffer. It just jumps to a different instruction instead of executing the next one in the source program order. - -Worth mentioning without any label specified as an argument, the branch command (`b`) will branch to the end of the program. So Sed will start a new cycle. This may be useful to bypass some instructions and thus may be used as an alternative to blocks: -``` -cat -n inputfile | sed -ne ' -/usb/!b -/daemon/!b -p -' - -``` - -#### Conditional branch - -Until now, we’ve seen the so-called unconditional branches, even if the term is somewhat misleading in this context since Sed commands are always conditional based on their optional address. - -However, in a more traditional sense, an unconditional branch is a branch that, when executed, will always jump to the specified destination, whereas a conditional branch may or may not jump to the specified instruction depending on the current state of the system. - -Sed has only one conditional instruction, the test (`t`) command. It jumps to a different instruction only if a substitution was executed since the start of the current cycle or since the previous conditional branch. More formally, the test command will branch only if the substitution flag is set. - -![The Sed `test` command][3]![The Sed `test` command][33] - -With the test instruction, you can easily perform loops in a Sed program. As a practical example, you can use that to pad lines to a certain length (something you can’t do with regex only): -``` -# Center text -cut -d: -f1 inputfile | sed -Ee ' - :start - s/^(.{,19})$/ \1 / # Pad lines shorter than 20 chars with - # a space at the start and another one - # at the end - t start # Go back to :start if we added a space - s/(.{20}).*/| \1 |/ # Keep only the first 20 char of the line - # to fix the off-by-one error caused by - # odd lines -' - -``` - -If you carefully read the previous example, you’ve noticed I cheated a little bit by using the cut command to pre-process the data before feeding them to sed. - -We can, however, perform the same task using only sed at the cost of a small modification to the program: -``` -cat inputfile | sed -Ee ' - s/:.*// # Remove all but the first field - t start - :start - s/^(.{,19})$/ \1 / # Pad lines shorter than 20 chars with - # a space at the start and another one - # at the end - t start # Go back to :start if we added a space - s/(.{20}).*/| \1 |/ # Keep only the first 20 char of the line - # to fix the off-by-one error caused by - # odd lines -' - -``` - -In the above example, you may be surprised by the following construct: -``` -t start -:start - -``` - -At first sight, the branch here seems useless since it will jump to the instruction that would have been executed anyway. However, if you read the definition of the `test` command attentively, you will see it branches only if there was a substitution since the start of the current cycle or since the previous test command was executed. In other words, the test instruction has the side effect of clearing the substitution flag. This is exactly the purpose of the code fragment above. This is a trick you will often see in Sed programs containing conditional branches to avoid false positive when using several substitutions commands. - -I agree though it wasn’t absolutely mandatory here to clear the substitution flag since the specific substitution command I used is idempotent once it has padded the string to the right length. So one extra iteration will not change the result. However, look at that second example now: -``` -# Classify user accounts based on their login program -cat inputfile | sed -Ene ' - s/^/login=/ - /nologin/s/^/type=SERV / - /false/s/^/type=SERV / - t print - s/^/type=USER / - :print - s/:.*//p -' - -``` - -My hope here was to tag the user accounts with either “SERV” or “USER” depending on the configured default login program. If you ran it, you’ve seen the “SERV” tag as expected. However, no trace of the “USER” tag in the output. Why? Because the `t print` instruction will always branch since whatever was the content of the line, the substitution flag was set by the very first substitution command of the program. Once set, the flag remains set until a next line is read— or until the next test command. And gives us the solution to fix that program: -``` -# Classify user accounts based on the login program -cat inputfile | sed -Ene ' - s/^/login=/ - - t classify # clear the "substitution flag" - :classify - - /nologin/s/^/type=SERV / - /false/s/^/type=SERV / - t print - s/^/type=USER / - :print - s/:.*//p -' - -``` - -### Handling verbatim text - -Sed is a text editor. A non-interactive one. But a text editor nevertheless. It wouldn’t be complete without some facility to insert literal text in the output. I’m not a big fan of that feature since I find the syntax awkward (even by the Sed standards), but sometimes you can’t avoid it. - -In the strict POSIX syntax, all the three commands to change (`c`), insert (`i`) or append (`a`) some literal text to the output follow the same specific syntax: the command letter is followed by a backslash, and the text to insert start on the next line of the script: -``` -head -5 inputfile | sed ' -1i\ -# List of user accounts -$a\ -# end -' - -``` - -To insert multiple lines of text, you must end each of them with a backslash: -``` -head -5 inputfile | sed ' -1i\ -# List of user accounts\ -# (users 1 through 5) -$a\ -# end -' - -``` - -Some Sed implementations, like GNU Sed, makes the newline after the initial backslash optional, even when forced in `--posix` mode. I didn’t find anything in the standard that authorizes that alternate syntax. So use it at your own risks if portability is a premium (or leave a comment if I missed that feature in the specifications!): -``` -# non-POSIX syntax: -head -5 inputfile | sed -e ' -1i \# List of user accounts -$a\# end -' - -``` - -Some Sed implementation also makes the initial backslash completely optional. Since this is, without any doubt this time, a vendor-specific extension to the POSIX specifications, I let you check the manual for the version of sed you use to check if it supports that syntax. - -After that quick overview, let’s review those commands in more details now, starting with the change command I didn’t have presented yet. - -#### The change command - -The change command (`c\`) deletes the pattern space and starts a new cycle just like the `d` command. The only difference is the user provided text is written on the output when the command is executed. - -![The Sed `change` command][34] -``` -cat -n inputfile | sed -e ' -/systemd/c\ -# :REMOVED: -s/:.*// # This will NOT be applied to the "changed" text -' - -``` - -If the change command is associated with a range address, the text is output only once, when reaching the last line of the range. Which somehow makes it an exception to the convention a Sed command is repeatedly applied to all lines of its range address: -``` -cat -n inputfile | sed -e ' -19,22c\ -# :REMOVED: -s/:.*// # This will NOT be applied to the "changed" text -' - -``` - -As a consequence, if you want the change command to be repeated for every line in a range, you have no other choice than wrapping it inside a block: -``` -cat -n inputfile | sed -e ' -19,22{c\ -# :REMOVED: -} -s/:.*// # This will NOT be applied to the "changed" text -' - -``` - -#### The insert command - -The insert command (`i\`) immediately print the user-provided text on the output. It does not alter in any way the program flow or buffer content. - -![The Sed `insert` command][35] -``` -# display the first five user names with a title on the first row -sed < inputfile -e ' -1i\ -USER NAME -s/:.*// -5q -' - -``` - -#### The append command - -The append command (`a\`) queues some text to be displayed when the next line of input will be read. The text is output at the end of the current cycle (including at the end of the program) or when a new line is read from the input using either the `n` or `N` command. - -![The Sed `append` command][36] - -Same example as above, but inserts this time a footer instead of a header: -``` -sed < inputfile -e ' -5a\ -USER NAME -s/:.*// -5q -' - -``` - -#### The read command - -There is a fourth command to insert literal content into the output stream: the read command (`r`). It works exactly like the append command, but instead of taking the text hardcoded from the Sed script itself, it will write the content of a file on the output. - -The read command only schedules the file to be read. That latter is effectively read when the append queue is flushed. Not when the read command is executed. This may have implications if there are concurrent accesses to the file to be read, if that file is not a regular file (for example, if it’s a character device or a named pipe), or if the file is modified during processing. - -As an illustration, if you use the write command we will see in detail in the next section together with the read command to write and re-read from a temporary file, you may obtain some creative results (using a French equivalent of the [Shiritori][37] game as an illustration): -``` -printf "%s\n" "Trois p'tits chats" "Chapeau d' paille" "Paillasson" | -sed -ne ' - r temp - a\ - ---- - w temp -' - -``` - -We’ve now ended the list of the Sed commands dedicated to the insertion of literal text in the stream output. My last example was mostly for fun, but since I mentioned there the write command, that makes a perfect transition with the next section where we will see how to write data to an external file from Sed. - -### Alternate output - -Sed is designed with the idea all text transformations will end-up being written on the standard output of the process. However, Sed also has some provision to send data to alternate destinations. You have two ways to do that: using the dedicated write command, or by adding the write flag to a substitution command. - -#### The write command - -The write command (`w`) appends the content of the pattern space to the given destination file. POSIX requires the destination file to be created by Sed before it starts processing any input data. If the file already exists, it is overwritten. - -![The Sed `write` command][38] - -As a consequence, even if you never really write to a file, it will be created anyway. For example, the following Sed program will create/overwrite the “output” file, even if the write command is never executed: -``` -echo | sed -ne ' -q # immediately quit -w output # this command is never executed -' - -``` - -You can have several write commands referencing the same destination file. All write commands at the destination of the same file will append content to that file (more or less in the same manner as the `>>` shell redirection). : -``` -sed < inputfile -ne ' -/:\/bin\/false$/w server -/:\/usr\/sbin\/nologin$/w server -w output -' -cat server - -``` - -#### The substitution command `write` flag - -A long time ago now, we had seen the substitution command has the `p` option for the common use case of printing the pattern space after a substitution. In a very similar manner it also has a `w` option to write the pattern space to a file after a substitution: -``` -sed < inputfile -ne ' -s/:.*\/nologin$//w server -s/:.*\/false$//w server -' -cat server - -``` - -I already used them countless times, but I never took the time to introduce them formally, so, let’s fix that: like in most programming languages, a comment is a way to add free-form text the software will not try to interpret. The Sed syntax being rather cryptic, I can’t insist enough on the need to comment your scripts. Otherwise, they will be hardly understandable by anyone except their author. - -![The Sed `comment` command][39] - -However, like many other parts of Sed, comments have their own share of subtleties. First, and the most important, comments are not a syntactic construct, but are full-fledged commands in Sed. A do-nothing (“no-op”) command, but a command anyway. At least, that is how there are defined by POSIX. So, strictly speaking, they should only be allowed where other commands are allowed. - -Most Sed implementation relaxes that requirement by allowing inline commands as I used them all over the place in that article. - -To close on that topic, worth mentioning the very special case of the `#n` comment (an octothorpe followed by the letter n without any space). If that exact comment if found on the very first line of a script, Sed should switch to quiet mode (i.e., clearing the auto-print flag) just like if the `-n` option was specified on the command line. - -### The commands you will rarely need - -Now, we have reviewed the commands that will allow you to write 99.99% of your scripts. But this tour wouldn’t be exhaustive if I didn’t mention the last remaining Sed commands. I left them aside until now because I rarely needed them. But maybe did you have on your side examples of practical use cases where you find them useful. If that is the case do not hesitate to share that with us using the comment section. - -#### The line number command - -The `=` command writes on the standard output the number of lines currently read by Sed, that is the content of the line counter register. There is no way to capture that number in one of the Sed buffers, nor to format the output. Two limitations that severely reduce the usefulness of that command. - -![The Sed `line number` command][40] - -Remember in strict POSIX compliance mode, when several input files are given on the command line, Sed does not reset that counter but continue to increment it just like if all the files where concatenated. Some Sed implementations like GNU Sed have options to reset the counter after each input file. - -#### The unambiguous print command - -The `l` (lowercase letter ell) is similar to the print command (`p`), but the content of the pattern space will be written in an unambiguous form. To quote [the POSIX standard][12]: - -> The characters listed in XBD Escape Sequences and Associated Actions ( ‘\\\’, ‘\a’, ‘\b’, ‘\f’, ‘\r’, ‘\t’, ‘\v’ ) shall be written as the corresponding escape sequence; the ‘\n’ in that table is not applicable. Non-printable characters not in that table shall be written as one three-digit octal number (with a preceding ) for each byte in the character (most significant byte first). Long lines shall be folded, with the point of folding indicated by writing a followed by a ; the length at which folding occurs is unspecified, but should be appropriate for the output device. The end of each line shall be marked with a ‘$’. - -![The Sed `unambiguous print` command][3]![The Sed `unambiguous print` command][41] - -I suspect this command was once used to exchange data over non [8-bits clean channels][42]. As of myself, I never used it for anything else than for debugging purposes. - -#### The transliterate command - -The transliterate (`y`) command allows mapping characters of the pattern space from a source set to a destination set. It is quite similar to the `tr` command, although more limited. - -![The Sed `transliterate` command][43] -``` -# The `y` c0mm4nd 1s for h4x0rz only -sed < inputfile -e ' - s/:.*// - y/abcegio/48<3610/ -' - -``` - -While the transliterate command syntax bears some resemblances with the substitution command syntax, it does not accept any option after the replacement string. The transliteration is always global. - -Beware that the transliterate command requires all the characters both in the original and destination set to be given verbatim. That means the following Sed program does not do what you might think at first sight: -``` -# BEWARE: this doesn't do what you may think! -sed < inputfile -e ' - s/:.*// - y/[a-z]/[A-Z]/ -' - -``` - -### The last word -``` -# What will this do? -# Hint: the answer is not far away... -sed -E ' - s/.*\W(.*)/\1/ - h - ${ x; p; } - d' < inputfile - -``` - -I can’t believe we did it! We’ve reviewed all the Sed commands. If you reached that point, you deserve congratulations, especially if you took the time to try the different examples on your system! - -As you’ve seen, Sed is a complex beast, not only because of its sparse syntax but also because of all the various corner cases or subtle differences in the command behavior. No doubt, we can blame historical reasons for that. Despite these drawbacks, it is a powerful tool and even today remains one of the most useful commands of the Unix toolbox. If it is time for me to conclude that article, I wouldn’t do it without first asking you a favor: please, share with us using the command section your most favorite or creative piece of Sed script. If we have enough of them, we could publish a compilation of those Sed gems! - --------------------------------------------------------------------------------- - -via: https://linuxhandbook.com/sed-reference-guide/ - -作者：[Sylvain Leroux][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://linuxhandbook.com/author/sylvain/ -[1]:https://linuxhandbook.com/sed-command-basics/ -[2]:https://gist.github.com/s-leroux/5cb36435bac46c10cfced26e4bf5588c -[3]:https://linuxhandbook.com/wp-content/plugins/jetpack/modules/lazy-images/images/1x1.trans.gif -[4]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05/sed-reference-guide.jpeg?resize=702%2C395&ssl=1 -[5]:http://mathworld.wolfram.com/AbstractMachine.html -[6]:https://en.wikipedia.org/wiki/State_(computer_science) -[7]:https://en.wikipedia.org/wiki/Data_buffer -[8]:https://en.wikipedia.org/wiki/Processor_register#Categories_of_registers -[9]:https://www.computerhope.com/jargon/f/flag.htm -[10]:https://i1.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-flowchart.png?w=702&ssl=1 -[11]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-print-command.png?w=702&ssl=1 -[12]:http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sed.html -[13]:https://www.regular-expressions.info/ -[14]:https://chortle.ccsu.edu/FiniteAutomata/Section07/sect07_16.html -[15]:https://www.regular-expressions.info/posix.html#bre -[16]:https://www.regular-expressions.info/posix.html#ere -[17]:https://www.regular-expressions.info/repeat.html#limit -[18]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-quit-command.png?w=702&ssl=1 -[19]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-substitution-command.png?w=702&ssl=1 -[20]:https://linuxhandbook.com/?p=128 -[21]:https://www.regular-expressions.info/repeat.html#greedy -[22]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-delete-command.png?w=702&ssl=1 -[23]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-next-command.png?w=702&ssl=1 -[24]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-exchange-command.png?w=702&ssl=1 -[25]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-hold-command.png?w=702&ssl=1 -[26]:https://i1.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-get-command.png?w=702&ssl=1 -[27]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-delete-upper-command.png?w=702&ssl=1 -[28]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-next-upper-command.png?w=702&ssl=1 -[29]:https://en.wikipedia.org/wiki/FIFO_(computing_and_electronics) -[30]:https://chortle.ccsu.edu/StructuredC/Chap01/struct01_5.html -[31]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-branch-command.png?w=702&ssl=1 -[32]:https://i1.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-label-command.png?w=702&ssl=1 -[33]:https://i1.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-test-command.png?w=702&ssl=1 -[34]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-change-command.png?w=702&ssl=1 -[35]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-insert-command.png?w=702&ssl=1 -[36]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-append-command.png?w=702&ssl=1 -[37]:https://en.wikipedia.org/wiki/Shiritori -[38]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-write-command.png?w=702&ssl=1 -[39]:https://i1.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-comment-command.png?w=702&ssl=1 -[40]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-current-line-command.png?w=702&ssl=1 -[41]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-unambiguous-print-command.png?w=702&ssl=1 -[42]:https://en.wikipedia.org/wiki/8-bit_clean -[43]:https://i1.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-transliterate-command.png?w=702&ssl=1 diff --git a/sources/tech/20180912 How to build rpm packages.md b/sources/tech/20180912 How to build rpm packages.md deleted file mode 100644 index 3d14a8c797..0000000000 --- a/sources/tech/20180912 How to build rpm packages.md +++ /dev/null @@ -1,397 +0,0 @@ -translating by Flowsnow - -How to build rpm packages -====== - -Save time and effort installing files and scripts across multiple hosts. - -![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/OSDC_gift_giveaway_box_520x292.png?itok=w1YQhNH1) - -I have used rpm-based package managers to install software on Red Hat and Fedora Linux since I started using Linux more than 20 years ago. I have used the **rpm** program itself, **yum** , and **DNF** , which is a close descendant of yum, to install and update packages on my Linux hosts. The yum and DNF tools are wrappers around the rpm utility that provide additional functionality, such as the ability to find and install package dependencies. - -Over the years I have created a number of Bash scripts, some of which have separate configuration files, that I like to install on most of my new computers and virtual machines. It reached the point that it took a great deal of time to install all of these packages, so I decided to automate that process by creating an rpm package that I could copy to the target hosts and install all of these files in their proper locations. Although the **rpm** tool was formerly used to build rpm packages, that function was removed and a new tool,was created to build new rpms. - -When I started this project, I found very little information about creating rpm packages, but I managed to find a book, Maximum RPM, that helped me figure it out. That book is now somewhat out of date, as is the vast majority of information I have found. It is also out of print, and used copies go for hundreds of dollars. The online version of [Maximum RPM][1] is available at no charge and is kept up to date. The [RPM website][2] also has links to other websites that have a lot of documentation about rpm. What other information there is tends to be brief and apparently assumes that you already have a good deal of knowledge about the process. - -In addition, every one of the documents I found assumes that the code needs to be compiled from sources as in a development environment. I am not a developer. I am a sysadmin, and we sysadmins have different needs because we don’t—or we shouldn’t—compile code to use for administrative tasks; we should use shell scripts. So we have no source code in the sense that it is something that needs to be compiled into binary executables. What we have is a source that is also the executable. - -For the most part, this project should be performed as the non-root user student. Rpms should never be built by root, but only by non-privileged users. I will indicate which parts should be performed as root and which by a non-root, unprivileged user. - -### Preparation - -First, open one terminal session and `su` to root. Be sure to use the `-` option to ensure that the complete root environment is enabled. I do not believe that sysadmins should use `sudo` for any administrative tasks. Find out why in my personal blog post: [Real SysAdmins don’t sudo][3]. - -``` -[student@testvm1 ~]$ su - -Password: -[root@testvm1 ~]# -``` - -Create a student user that can be used for this project and set a password for that user. - -``` -[root@testvm1 ~]# useradd -c "Student User" student -[root@testvm1 ~]# passwd student -Changing password for user student. -New password: -Retype new password: -passwd: all authentication tokens updated successfully. -[root@testvm1 ~]# -``` - -Building rpm packages requires the `rpm-build` package, which is likely not already installed. Install it now as root. Note that this command will also install several dependencies. The number may vary, depending upon the packages already installed on your host; it installed a total of 17 packages on my test VM, which is pretty minimal. - -``` -dnf install -y rpm-build -``` - -The rest of this project should be performed as the user student unless otherwise explicitly directed. Open another terminal session and use `su` to switch to that user to perform the rest of these steps. Download a tarball that I have prepared of a development directory structure, utils.tar, from GitHub using the following command: - -``` -wget https://github.com/opensourceway/how-to-rpm/raw/master/utils.tar -``` - -This tarball includes all of the files and Bash scripts that will be installed by the final rpm. There is also a complete spec file, which you can use to build the rpm. We will go into detail about each section of the spec file. - -As user student, using your home directory as your present working directory (pwd), untar the tarball. - -``` -[student@testvm1 ~]$ cd ; tar -xvf utils.tar -``` - -Use the `tree` command to verify that the directory structure of ~/development and the contained files looks like the following output: - -``` -[student@testvm1 ~]$ tree development/ -development/ -├── license -│   ├── Copyright.and.GPL.Notice.txt -│   └── GPL_LICENSE.txt -├── scripts -│   ├── create_motd -│   ├── die -│   ├── mymotd -│   └── sysdata -└── spec -    └── utils.spec - -3 directories, 7 files -[student@testvm1 ~]$ -``` - -The `mymotd` script creates a “Message Of The Day” data stream that is sent to stdout. The `create_motd` script runs the `mymotd` scripts and redirects the output to the /etc/motd file. This file is used to display a daily message to users who log in remotely using SSH. - -The `die` script is my own script that wraps the `kill` command in a bit of code that can find running programs that match a specified string and kill them. It uses `kill -9` to ensure that they cannot ignore the kill message. - -The `sysdata` script can spew tens of thousands of lines of data about your computer hardware, the installed version of Linux, all installed packages, and the metadata of your hard drives. I use it to document the state of a host at a point in time. I can later use it for reference. I used to do this to maintain a record of hosts that I installed for customers. - -You may need to change ownership of these files and directories to student.student. Do this, if necessary, using the following command: - -``` -chown -R student.student development -``` - -Most of the files and directories in this tree will be installed on Fedora systems by the rpm you create during this project. - -### Creating the build directory structure - -The `rpmbuild` command requires a very specific directory structure. You must create this directory structure yourself because no automated way is provided. Create the following directory structure in your home directory: - -``` -~ ─ rpmbuild -    ├── RPMS -    │   └── noarch -    ├── SOURCES -    ├── SPECS -    └── SRPMS -``` - -We will not create the rpmbuild/RPMS/X86_64 directory because that would be architecture-specific for 64-bit compiled binaries. We have shell scripts that are not architecture-specific. In reality, we won’t be using the SRPMS directory either, which would contain source files for the compiler. - -### Examining the spec file - -Each spec file has a number of sections, some of which may be ignored or omitted, depending upon the specific circumstances of the rpm build. This particular spec file is not an example of a minimal file required to work, but it is a good example of a moderately complex spec file that packages files that do not need to be compiled. If a compile were required, it would be performed in the `%build` section, which is omitted from this spec file because it is not required. - -#### Preamble - -This is the only section of the spec file that does not have a label. It consists of much of the information you see when the command `rpm -qi [Package Name]` is run. Each datum is a single line which consists of a tag, which identifies it and text data for the value of the tag. - -``` -############################################################################### -# Spec file for utils -################################################################################ -# Configured to be built by user student or other non-root user -################################################################################ -# -Summary: Utility scripts for testing RPM creation -Name: utils -Version: 1.0.0 -Release: 1 -License: GPL -URL: http://www.both.org -Group: System -Packager: David Both -Requires: bash -Requires: screen -Requires: mc -Requires: dmidecode -BuildRoot: ~/rpmbuild/ - -# Build with the following syntax: -# rpmbuild --target noarch -bb utils.spec -``` - -Comment lines are ignored by the `rpmbuild` program. I always like to add a comment to this section that contains the exact syntax of the `rpmbuild` command required to create the package. The Summary tag is a short description of the package. The Name, Version, and Release tags are used to create the name of the rpm file, as in utils-1.00-1.rpm. Incrementing the release and version numbers lets you create rpms that can be used to update older ones. - -The License tag defines the license under which the package is released. I always use a variation of the GPL. Specifying the license is important to clarify the fact that the software contained in the package is open source. This is also why I included the license and GPL statement in the files that will be installed. - -The URL is usually the web page of the project or project owner. In this case, it is my personal web page. - -The Group tag is interesting and is usually used for GUI applications. The value of the Group tag determines which group of icons in the applications menu will contain the icon for the executable in this package. Used in conjunction with the Icon tag (which we are not using here), the Group tag allows adding the icon and the required information to launch a program into the applications menu structure. - -The Packager tag is used to specify the person or organization responsible for maintaining and creating the package. - -The Requires statements define the dependencies for this rpm. Each is a package name. If one of the specified packages is not present, the DNF installation utility will try to locate it in one of the defined repositories defined in /etc/yum.repos.d and install it if it exists. If DNF cannot find one or more of the required packages, it will throw an error indicating which packages are missing and terminate. - -The BuildRoot line specifies the top-level directory in which the `rpmbuild` tool will find the spec file and in which it will create temporary directories while it builds the package. The finished package will be stored in the noarch subdirectory that we specified earlier. The comment showing the command syntax used to build this package includes the option `–target noarch`, which defines the target architecture. Because these are Bash scripts, they are not associated with a specific CPU architecture. If this option were omitted, the build would be targeted to the architecture of the CPU on which the build is being performed. - -The `rpmbuild` program can target many different architectures, and using the `--target` option allows us to build architecture-specific packages on a host with a different architecture from the one on which the build is performed. So I could build a package intended for use on an i686 architecture on an x86_64 host, and vice versa. - -Change the packager name to yours and the URL to your own website if you have one. - -#### %description - -The `%description` section of the spec file contains a description of the rpm package. It can be very short or can contain many lines of information. Our `%description` section is rather terse. - -``` -%description -A collection of utility scripts for testing RPM creation. -``` - -#### %prep - -The `%prep` section is the first script that is executed during the build process. This script is not executed during the installation of the package. - -This script is just a Bash shell script. It prepares the build directory, creating directories used for the build as required and copying the appropriate files into their respective directories. This would include the sources required for a complete compile as part of the build. - -The $RPM_BUILD_ROOT directory represents the root directory of an installed system. The directories created in the $RPM_BUILD_ROOT directory are fully qualified paths, such as /user/local/share/utils, /usr/local/bin, and so on, in a live filesystem. - -In the case of our package, we have no pre-compile sources as all of our programs are Bash scripts. So we simply copy those scripts and other files into the directories where they belong in the installed system. - -``` -%prep -################################################################################ -# Create the build tree and copy the files from the development directories    # -# into the build tree.                                                         # -################################################################################ -echo "BUILDROOT = $RPM_BUILD_ROOT" -mkdir -p $RPM_BUILD_ROOT/usr/local/bin/ -mkdir -p $RPM_BUILD_ROOT/usr/local/share/utils - -cp /home/student/development/utils/scripts/* $RPM_BUILD_ROOT/usr/local/bin -cp /home/student/development/utils/license/* $RPM_BUILD_ROOT/usr/local/share/utils -cp /home/student/development/utils/spec/* $RPM_BUILD_ROOT/usr/local/share/utils - -exit -``` - -Note that the exit statement at the end of this section is required. - -#### %files - -This section of the spec file defines the files to be installed and their locations in the directory tree. It also specifies the file attributes and the owner and group owner for each file to be installed. The file permissions and ownerships are optional, but I recommend that they be explicitly set to eliminate any chance for those attributes to be incorrect or ambiguous when installed. Directories are created as required during the installation if they do not already exist. - -``` -%files -%attr(0744, root, root) /usr/local/bin/* -%attr(0644, root, root) /usr/local/share/utils/* -``` - -#### %pre - -This section is empty in our lab project’s spec file. This would be the place to put any scripts that are required to run during installation of the rpm but prior to the installation of the files. - -#### %post - -This section of the spec file is another Bash script. This one runs after the installation of files. This section can be pretty much anything you need or want it to be, including creating files, running system commands, and restarting services to reinitialize them after making configuration changes. The `%post` script for our rpm package performs some of those tasks. - -``` -%post -################################################################################ -# Set up MOTD scripts                                                          # -################################################################################ -cd /etc -# Save the old MOTD if it exists -if [ -e motd ] -then -   cp motd motd.orig -fi -# If not there already, Add link to create_motd to cron.daily -cd /etc/cron.daily -if [ ! -e create_motd ] -then -   ln -s /usr/local/bin/create_motd -fi -# create the MOTD for the first time -/usr/local/bin/mymotd > /etc/motd -``` - -The comments included in this script should make its purpose clear. - -#### %postun - -This section contains a script that would be run after the rpm package is uninstalled. Using rpm or DNF to remove a package removes all of the files listed in the `%files` section, but it does not remove files or links created by the `%post` section, so we need to handle that in this section. - -This script usually consists of cleanup tasks that simply erasing the files previously installed by the rpm cannot accomplish. In the case of our package, it includes removing the link created by the `%post` script and restoring the saved original of the motd file. - -``` -%postun -# remove installed files and links -rm /etc/cron.daily/create_motd - -# Restore the original MOTD if it was backed up -if [ -e /etc/motd.orig ] -then -   mv -f /etc/motd.orig /etc/motd -fi -``` - -#### %clean - -This Bash script performs cleanup after the rpm build process. The two lines in the `%clean` section below remove the build directories created by the `rpm-build` command. In many cases, additional cleanup may also be required. - -``` -%clean -rm -rf $RPM_BUILD_ROOT/usr/local/bin -rm -rf $RPM_BUILD_ROOT/usr/local/share/utils -``` - -#### %changelog - -This optional text section contains a list of changes to the rpm and files it contains. The newest changes are recorded at the top of this section. - -``` -%changelog -* Wed Aug 29 2018 Your Name -  - The original package includes several useful scripts. it is -    primarily intended to be used to illustrate the process of -    building an RPM. -``` - -Replace the data in the header line with your own name and email address. - -### Building the rpm - -The spec file must be in the SPECS directory of the rpmbuild tree. I find it easiest to create a link to the actual spec file in that directory so that it can be edited in the development directory and there is no need to copy it to the SPECS directory. Make the SPECS directory your pwd, then create the link. - -``` -cd ~/rpmbuild/SPECS/ -ln -s ~/development/spec/utils.spec -``` - -Run the following command to build the rpm. It should only take a moment to create the rpm if no errors occur. - -``` -rpmbuild --target noarch -bb utils.spec -``` - -Check in the ~/rpmbuild/RPMS/noarch directory to verify that the new rpm exists there. - -``` -[student@testvm1 ~]$ cd rpmbuild/RPMS/noarch/ -[student@testvm1 noarch]$ ll -total 24 --rw-rw-r--. 1 student student 24364 Aug 30 10:00 utils-1.0.0-1.noarch.rpm -[student@testvm1 noarch]$ -``` - -### Testing the rpm - -As root, install the rpm to verify that it installs correctly and that the files are installed in the correct directories. The exact name of the rpm will depend upon the values you used for the tags in the Preamble section, but if you used the ones in the sample, the rpm name will be as shown in the sample command below: - -``` -[root@testvm1 ~]# cd /home/student/rpmbuild/RPMS/noarch/ -[root@testvm1 noarch]# ll -total 24 --rw-rw-r--. 1 student student 24364 Aug 30 10:00 utils-1.0.0-1.noarch.rpm -[root@testvm1 noarch]# rpm -ivh utils-1.0.0-1.noarch.rpm -Preparing...                          ################################# [100%] -Updating / installing... -   1:utils-1.0.0-1                    ################################# [100%] -``` - -Check /usr/local/bin to ensure that the new files are there. You should also verify that the create_motd link in /etc/cron.daily has been created. - -Use the `rpm -q --changelog utils` command to view the changelog. View the files installed by the package using the `rpm -ql utils` command (that is a lowercase L in `ql`.) - -``` -[root@testvm1 noarch]# rpm -q --changelog utils -* Wed Aug 29 2018 Your Name -- The original package includes several useful scripts. it is -    primarily intended to be used to illustrate the process of -    building an RPM. - -[root@testvm1 noarch]# rpm -ql utils -/usr/local/bin/create_motd -/usr/local/bin/die -/usr/local/bin/mymotd -/usr/local/bin/sysdata -/usr/local/share/utils/Copyright.and.GPL.Notice.txt -/usr/local/share/utils/GPL_LICENSE.txt -/usr/local/share/utils/utils.spec -[root@testvm1 noarch]# -``` - -Remove the package. - -``` -rpm -e utils -``` - -### Experimenting - -Now you will change the spec file to require a package that does not exist. This will simulate a dependency that cannot be met. Add the following line immediately under the existing Requires line: - -``` -Requires: badrequire -``` - -Build the package and attempt to install it. What message is displayed? - -We used the `rpm` command to install and delete the `utils` package. Try installing the package with yum or DNF. You must be in the same directory as the package or specify the full path to the package for this to work. - -### Conclusion - -There are many tags and a couple sections that we did not cover in this look at the basics of creating an rpm package. The resources listed below can provide more information. Building rpm packages is not difficult; you just need the right information. I hope this helps you—it took me months to figure things out on my own. - -We did not cover building from source code, but if you are a developer, that should be a simple step from this point. - -Creating rpm packages is another good way to be a lazy sysadmin and save time and effort. It provides an easy method for distributing and installing the scripts and other files that we as sysadmins need to install on many hosts. - -### Resources - - * Edward C. Baily, Maximum RPM, Sams Publishing, 2000, ISBN 0-672-31105-4 - - * Edward C. Baily, [Maximum RPM][1], updated online version - - * [RPM Documentation][4]: This web page lists most of the available online documentation for rpm. It includes many links to other websites and information about rpm. - - - - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/9/how-build-rpm-packages - -作者：[David Both][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://opensource.com/users/dboth -[1]: http://ftp.rpm.org/max-rpm/ -[2]: http://rpm.org/index.html -[3]: http://www.both.org/?p=960 -[4]: http://rpm.org/documentation.html diff --git a/sources/tech/20181004 Lab 3- User Environments.md b/sources/tech/20181004 Lab 3- User Environments.md index 2dc1522b69..4af7c09eba 100644 --- a/sources/tech/20181004 Lab 3- User Environments.md +++ b/sources/tech/20181004 Lab 3- User Environments.md @@ -1,3 +1,4 @@ +Translating by qhwdw Lab 3: User Environments ====== ### Lab 3: User Environments diff --git a/sources/tech/20181013 How to Install GRUB on Arch Linux (UEFI).md b/sources/tech/20181013 How to Install GRUB on Arch Linux (UEFI).md deleted file mode 100644 index e456c1ee0e..0000000000 --- a/sources/tech/20181013 How to Install GRUB on Arch Linux (UEFI).md +++ /dev/null @@ -1,76 +0,0 @@ -translating---geekpi - -How to Install GRUB on Arch Linux (UEFI) -====== - -![](http://fasterland.net/wp-content/uploads/2018/10/Arch-Linux-Boot-Menu-750x375.jpg) - -Some time ago, I wrote a tutorial on **[how to reinstall Grub][1] on Arch Linux after installing Windows.** - -A few weeks ago, I had to reinstall **Arch Linux** from scratch on my laptop and I discovered installing **Grub** was not as straightforward as I remembered. - -For this reason, I’m going to write this tutorial since **installing Grub on a UEFI bios** during a new **Arch Linux** installation it’s not too easy. - -### Locating the EFI partition - -The first important thing to do for installing **Grub** on **Arch Linux** is to locate the **EFI** partition. -Let’s run the following command in order to locate this partition: - -``` -# fdisk -l -``` - -We need to check the partition marked as **EFI System -**In my case is **/dev/sda2** - -After that, we need to mount this partition, for example, on /boot/efi: - -``` -# mkdir /boot/efi -# mount /dev/sdb2 /boot/efi -``` - -Another important thing to do is adding this partition into the **/etc/fstab** file. - -#### Installing Grub - -Now we can install Grub in our system: - -``` -# grub-mkconfig -o /boot/grub/grub.cfg -# grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=GRUB -``` - -#### Adding Windows Automatically into the Grub Menu - -In order to automatically add the **Windows entry into the Grub menu** , we need to install the **os-prober** program: - -``` -# pacman -Sy os-prober -``` - -In order to add the entry item let’s run the following commands: - -``` -# os-prober -# grub-mkconfig -o /boot/grub/grub.cfg -# grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=GRUB -``` - -You can find more about Grub on Arch Linux [here][2]. - --------------------------------------------------------------------------------- - -via: http://fasterland.net/how-to-install-grub-on-arch-linux-uefi.html - -作者：[Francesco Mondello][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://fasterland.net/ -[b]: https://github.com/lujun9972 -[1]: http://fasterland.net/reinstall-grub-arch-linux.html -[2]: https://wiki.archlinux.org/index.php/GRUB diff --git a/sources/tech/20181015 How To Browse And Read Entire Arch Wiki As Linux Man Pages.md b/sources/tech/20181015 How To Browse And Read Entire Arch Wiki As Linux Man Pages.md deleted file mode 100644 index fe61f32dda..0000000000 --- a/sources/tech/20181015 How To Browse And Read Entire Arch Wiki As Linux Man Pages.md +++ /dev/null @@ -1,151 +0,0 @@ -How To Browse And Read Entire Arch Wiki As Linux Man Pages -====== -![](https://www.ostechnix.com/wp-content/uploads/2018/10/arch-wiki-720x340.jpg) - -A while ago, I wrote a guide that described how to browse the Arch Wiki from your Terminal using a command line script named [**arch-wiki-cli**][1]. Using this script, anyone can easily navigate through entire Arch Wiki website and read it with a text browser of your choice. Obviously, an active Internet connection is required to use this script. Today, I stumbled upon a similar utility named **“Arch-wiki-man”**. As the name says, it is also used to read the Arch Wiki from command line, but it doesn’t require Internet connection. Arch-wiki-man program helps you to browse and read entire Arch Wiki as Linux man pages. It will display any article from Arch Wiki in man pages format. Also, you need not to be online to browse Arch Wiki. The entire Arch Wiki will be downloaded locally and the updates are pushed automatically every two days. So, you always have an up-to-date, local copy of the Arch Wiki on your system. - -### Installing Arch-wiki-man - -Arch-wiki-man is available in [**AUR**][2], so you can install it using any AUR helper programs, for example [**Yay**][3]. - -``` - $ yay -S arch-wiki-man -``` - -Alternatively, it can be installed using NPM package manager like below. Make sure you have [**installed NodeJS**][4] and run the following command to install it: - -``` - $ npm install -g arch-wiki-man -``` - -### Browse And Read Entire Arch Wiki As Linux Man Pages - -The typical syntax of Arch-wiki-man is: - -``` - $ awman -``` - -Let me show you some examples. - -**Search with one or more matches** - -Let us search for a [**Arch Linux installation guide**][5]. To do so, simply run: - -``` - $ awman Installation guide -``` - -The above command will search for the matches that contains the search term “Installation guide” in the Arch Wiki. If there are multiple matches for the given search term, a selection menu will appear. Choose the guide you want to read using **UP/DOWN arrows** or Vim-style keybindings ( **j/k** ) and hit ENTER to open it. The resulting guide will open in man pages format like below. - -![][6] - -Here, awman refers **a** rch **w** iki **m** an. - -All man command options are supported, so you can navigate through guide as the way you do when reading a man page. To view the help section, press **h**. - -![][7] - -To exit the selection menu without entering **man** , simply press **Ctrl+c**. - -To go back and/or quit man, type **q**. - -**Search matches in titles and descriptions** - -By default, Awman will search for the matches in titles only. You can, however, direct it to search for the matches in both the titles and descriptions as well. - -``` - $ awman -d vim -``` - -Or, - -``` - $ awman --desc-search vim -``` - -**Search for matches in contents** - -Apart from searching for matches in titles and descriptions, it is also possible to scan the contents for a match as well. Please note that this will significantly slower the search process. - -``` - $ awman -k emacs -``` - -Or, - -``` - $ awman --apropos emacs -``` - -**Open the search results in web browser** - -If you don’t want to view the arch wiki guides in man page format, you can open it in a web browser. To do so, run: - -``` - $ awman -w pacman -``` - -Or, - -``` - $ awman --web pacman -``` - -This command will open the resulting match in the default web browser rather than with **man** command. Please note that you need Internet connection to use this option. - -**Search in other languages** - -By default, Awman will open the Arch wiki pages in English. If you want to view the results in other languages, for example **Spanish** , simply do: - -``` - $ awman -l spanish codecs -``` - -![][8] - -To view the list of available language options, run: - -``` - - $ awman --list-languages - -``` - -**Update the local copy of Arch Wiki** - -Like I already said, the updates are pushed automatically every two days. If you want to update it manually, simply run: - -``` -$ awman-update -arch-wiki-man@1.3.0 /usr/lib/node_modules/arch-wiki-man -└── arch-wiki-md-repo@0.10.84 - -arch-wiki-md-repo has been successfully updated or reinstalled. -``` - -Cheers! - - - --------------------------------------------------------------------------------- - -via: https://www.ostechnix.com/how-to-browse-and-read-entire-arch-wiki-as-linux-man-pages/ - -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/search-arch-wiki-website-commandline/ -[2]: https://aur.archlinux.org/packages/arch-wiki-man/ -[3]: https://www.ostechnix.com/yay-found-yet-another-reliable-aur-helper/ -[4]: https://www.ostechnix.com/install-node-js-linux/ -[5]: https://www.ostechnix.com/install-arch-linux-latest-version/ -[6]: http://www.ostechnix.com/wp-content/uploads/2018/10/awman-1.gif -[7]: http://www.ostechnix.com/wp-content/uploads/2018/10/awman-2.png -[8]: https://www.ostechnix.com/wp-content/uploads/2018/10/awman-3-1.png diff --git a/sources/tech/20181016 Final JOS project.md b/sources/tech/20181016 Final JOS project.md index 929c1e7caa..401235d20d 100644 --- a/sources/tech/20181016 Final JOS project.md +++ b/sources/tech/20181016 Final JOS project.md @@ -1,3 +1,4 @@ +Translating by qhwdw Final JOS project ====== Piazza Discussion Due, November 2, 2018 Proposals Due, November 8, 2018 Code repository Due, December 6, 2018 Check-off and in-class demos, Week of December 10, 2018 diff --git a/sources/tech/20181016 Lab 4- Preemptive Multitasking.md b/sources/tech/20181016 Lab 4- Preemptive Multitasking.md index 9e510ed7c6..de68cd7f39 100644 --- a/sources/tech/20181016 Lab 4- Preemptive Multitasking.md +++ b/sources/tech/20181016 Lab 4- Preemptive Multitasking.md @@ -1,3 +1,4 @@ +Translating by qhwdw Lab 4: Preemptive Multitasking ====== ### Lab 4: Preemptive Multitasking diff --git a/sources/tech/20181016 Lab 5- File system, Spawn and Shell.md b/sources/tech/20181016 Lab 5- File system, Spawn and Shell.md index e7e623db11..9250700723 100644 --- a/sources/tech/20181016 Lab 5- File system, Spawn and Shell.md +++ b/sources/tech/20181016 Lab 5- File system, Spawn and Shell.md @@ -1,3 +1,4 @@ +Translating by qhwdw Lab 5: File system, Spawn and Shell ====== diff --git a/sources/tech/20181016 Lab 6- Network Driver.md b/sources/tech/20181016 Lab 6- Network Driver.md index 7c310e3d88..b9b9172b42 100644 --- a/sources/tech/20181016 Lab 6- Network Driver.md +++ b/sources/tech/20181016 Lab 6- Network Driver.md @@ -1,3 +1,4 @@ +Translating by qhwdw Lab 6: Network Driver ====== ### Lab 6: Network Driver (default final project) diff --git a/sources/tech/20181016 Turn Your Old PC into a Retrogaming Console with Lakka Linux.md b/sources/tech/20181016 Turn Your Old PC into a Retrogaming Console with Lakka Linux.md index 7475e9c1b3..08ef4a8dc2 100644 --- a/sources/tech/20181016 Turn Your Old PC into a Retrogaming Console with Lakka Linux.md +++ b/sources/tech/20181016 Turn Your Old PC into a Retrogaming Console with Lakka Linux.md @@ -1,3 +1,5 @@ +translating---geekpi + Turn Your Old PC into a Retrogaming Console with Lakka Linux ====== **If you have an old computer gathering dust, you can turn it into a PlayStation like retrogaming console with Lakka Linux distribution. ** diff --git a/sources/tech/20181018 4 open source alternatives to Microsoft Access.md b/sources/tech/20181018 4 open source alternatives to Microsoft Access.md new file mode 100644 index 0000000000..19f78e81d6 --- /dev/null +++ b/sources/tech/20181018 4 open source alternatives to Microsoft Access.md @@ -0,0 +1,94 @@ +4 open source alternatives to Microsoft Access +====== +Build simple business applications and keep track of your data with these worthy open source alternatives. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/bus_cloud_database.png?itok=lhhU42fg) + +When small businesses, community organizations, and similar-sized groups realize they need software to manage their data, they think first of Microsoft Access. That may be the right choice if you're already paying for a Microsoft Office subscription or don't care that it's proprietary. But it's far from your only option—whether you prefer to use open source alternatives from a philosophical standpoint or you don't have the big budget for a Microsoft Office subscription—there are several open source database applications that are worthy alternatives to proprietary software like Microsoft Access or Apple FileMaker. + +If that sounds like you, here are four open source database tools for your consideration. + +### LibreOffice Base + +![](https://opensource.com/sites/default/files/uploads/libreoffice-base.png) +In case it's not obvious from its name, [Base][1] is part of the [LibreOffice][2] productivity suite, which includes Writer (word processing), Calc (spreadsheet), Impress (presentations), Draw (graphics), Charts (chart creation), and Math (formulas). As such, Base integrates with the other LibreOffice applications, much like Access does with the Microsoft Office suite. This means you can import and export data from Base into the suite's other applications to create financial reports, mail merges, charts, and more. + +Base includes drivers that natively support multi-user database engines, including the open source MySQL, MariaDB, and PostgreSQL; Access; and other JDBC and ODBC-compliant databases. Built-in wizards and table definitions make it easy for new users to quickly get started building tables, writing queries, and creating forms and reports (such as invoices, sales reports, and customer lists). To learn more, consult the comprehensive [user manual][3] and dive into the [user forums][4]. If you're still stuck, you can find a [certified][5] support professional to help you out. + +Installers are available for Linux, MacOS, Windows, and Android. LibreOffice is available under the [Mozilla Public License v2][6]; if you'd like to join the large contributor community and help improve the software, visit the [Get Involved][7] section of LibreOffice's website. + +### DB Browser for SQLite + +![](https://opensource.com/sites/default/files/uploads/sqlitebrowser.png) + +[DB Browser for SQLite][8] enables users to create and use SQLite database files without having to know complex SQL commands. This, plus its spreadsheet-like interface and pre-built wizards, make it a great option for new database users to get going without much background knowledge. + +Although the application has gone through several name changes—from the original Arca Database Browser to the SQLite Database Browser and finally to the current name (in 2014, to avoid confusion with SQLite), it's stayed true to its goal of being easy for users to operate. + +Its wizards enable users to easily create and modify database files, tables, indexes, records, etc.; import and export data to common file formats; create and issue queries and searches; and more. Installers are available for Windows, MacOS, and a variety of Linux versions, and its [wiki on GitHub][9] offers a wealth of information for users and developers. + +DB Browser for SQLite is [bi-licensed][10] under the Mozilla Public License Version 2 and the GNU General Public License Version 3 or later, and you can download the source code from the project's website. + +### Kexi + +![](https://opensource.com/sites/default/files/uploads/kexi-3.0-table-view.png) +As the database application in the [Calligra Suite][11] productivity software for the KDE desktop, [Kexi][12] integrates with the other applications in the suite, including Words (word processing), Sheets (spreadsheet), Stage (presentations), and Plan (project management). + +As a full member of the [KDE][13] project, Kexi is purpose-built for KDE Plasma, but it's not limited to KDE users: Linux, BSD, and Unix users running GNOME can run the database, as can MacOS and Windows users. + +Kexi's website says its development was "motivated by the lack of rapid application development ([RAD][14]) tools for database systems that are sufficiently powerful, inexpensive, open standards driven, and portable across many operating systems and hardware platforms." It has all the standard features you'd expect: designing databases, storing data, doing queries, processing data, and so forth. + +Kexi is available under the [LGPL][15] open source license and you can download its [source code][16] from its development wiki. If you'd like to learn more, take a look at its [user handbook][17], [forums][18], and [userbase wiki][17]. + +### nuBuilder Forte + +![](https://opensource.com/sites/default/files/uploads/screenshot_from_2018-10-17_13-23-25.png) +[NuBuilder Forte][19] is designed to be as easy as possible for people to use. It's a browser-based tool for developing web-based database applications. + +Its clean interface and low-code tools (including support for drag-and-drop) allow users to create and use a database quickly. As a fully web-based application, data is accessible anywhere from a browser. Everything is stored in MySQL and can be backed up in one database file. + +It uses industry-standard coding languages—HTML, PHP, JavaScript, and SQL—making it easy for developers to get started also. + +Help is available in [videos][20] and other [documentation][21] for topics including creating forms, doing searches, building reports, and more. + +nuBuilder Forte is licensed under [GPLv3.0][22] and you can download it on [GitHub][23]. You can learn more by consulting the [nuBuilder Forum][24] or watching its [demo][25] video. + +Do you have a favorite open source database tool for building simple projects with little or no coding skill required? If so, please share in the comments. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/alternatives/access + +作者：[Opensource.com][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 +[b]: https://github.com/lujun9972 +[1]: https://www.libreoffice.org/discover/base/ +[2]: https://www.libreoffice.org/ +[3]: https://documentation.libreoffice.org/en/english-documentation/base/ +[4]: http://document-foundation-mail-archive.969070.n3.nabble.com/Users-f1639498.html +[5]: https://www.libreoffice.org/get-help/professional-support/ +[6]: https://www.libreoffice.org/download/license/ +[7]: https://www.libreoffice.org/community/get-involved/ +[8]: http://sqlitebrowser.org/ +[9]: https://github.com/sqlitebrowser/sqlitebrowser/wiki +[10]: https://github.com/sqlitebrowser/sqlitebrowser/blob/master/LICENSE +[11]: https://www.calligra.org/ +[12]: https://www.calligra.org/kexi/ +[13]: https://www.kde.org/ +[14]: http://en.wikipedia.org/wiki/Rapid_application_development +[15]: http://kexi-project.org/wiki/wikiview/index.php@KexiLicense.html +[16]: http://kexi-project.org/wiki/wikiview/index.php@Download.html +[17]: https://userbase.kde.org/Kexi/Handbook +[18]: http://forum.kde.org/kexi +[19]: https://www.nubuilder.com/ +[20]: https://www.nubuilder.com/videos +[21]: https://www.nubuilder.com/wiki +[22]: https://github.com/nuSoftware/nuBuilder4/blob/master/LICENSE.txt +[23]: https://github.com/nuSoftware/nuBuilder4 +[24]: https://forums.nubuilder.com/viewforum.php?f=18&sid=7036bccdc08ba0da73181bc72cd63c62 +[25]: https://www.youtube.com/watch?v=tdh9ILCUAco&feature=youtu.be diff --git a/sources/tech/20181018 MidnightBSD Hits 1.0- Checkout What-s New.md b/sources/tech/20181018 MidnightBSD Hits 1.0- Checkout What-s New.md new file mode 100644 index 0000000000..345a9f9b5b --- /dev/null +++ b/sources/tech/20181018 MidnightBSD Hits 1.0- Checkout What-s New.md @@ -0,0 +1,74 @@ +MidnightBSD Hits 1.0! Checkout What’s New +====== +A couple days ago, Lucas Holt announced the release of MidnightBSD 1.0. Let’s take a quick look at what is included in this new release. + +### What is MidnightBSD? + +![MidnightBSD][1] + +[MidnightBSD][2] is a fork of FreeBSD. Lucas created MightnightBSD to be an option for desktop users and for BSD newbies. He wanted to create something that would allow people to quickly get a desktop experience on BSD. He believed that other options had too much of a focus on the server market. + +### What is in MidnightBSD 1.0? + +According to the [release notes][3], most of the work in 1.0 went towards updating the base system, improving the package manager and updating tools. The new release is compatible with FreeBSD 10-Stable. + +Mports (MidnightBSD’s package management system) has been upgraded to support installing multiple packages with one command. The `mport upgrade` command has been fixed. Mports now tracks deprecated and expired packages. A new package format was also introduced. + + + +Other changes include: + + * [ZFS][4] is now supported as a boot file system. Previously, ZFS could only be used for additional storage. + * Support for NVME SSDs + * AMD Ryzen and Radeon support have been improved. + * Intel, Broadcom, and other drivers updated. + * bhyve support has been ported from FreeBSD + * The sensors framework was removed because it was causing locking issues. + * Sudo was removed and replaced with [doas][5] from OpenBSD. + * Added support for Microsoft hyper-v + + + +### Before you upgrade… + +If you are a current MidnightBSD user or are thinking of trying out the new release, it would be a good idea to wait. Lucas is currently rebuilding packages to support the new package format and tooling. He also plans to upgrade packages and ports for the desktop environment over the next couple of months. He is currently working on porting Firefox 52 ESR because it is the last release that does not require Rust. He also hopes to get a newer version of Chromium ported to MidnightBSD. I would recommend keeping an eye on the MidnightBSD [Twi][6][t][6][ter][6] feed. + +### What happened to 0.9? + +You might notice that the previous release of MidnightBSD was 0.8.6. Now, you might be wondering “Why the jump to 1.0”? According to Lucas, he ran into several issues while developing 0.9. In fact, he restarted it several times. He ending up taking CURRENT in a different direction than the 0.9 branch and it became 1.0. Some packages also had an issue with the 0.* numbering system. + +### Help Needed + +Currently, the MidnightBSD project is the work of pretty much one guy, Lucas Holt. This is the main reason why development has been slow. If you are interested in helping out, you can contact him on [Twitter][6]. + +In the [release announcement video][7]. Lucas said that he had encountered problems with upstream projects accepting patches. They seem to think that MidnightBSD is too small. This often means that he has to port an application from scratch. + +### Thoughts + +I have a thing for the underdog. Of all the BSDs that I have interacted with, that monicker fits MidnightBSD the most. One guy trying to create an easy desktop experience. Currently, there is only one other BSD trying to do something similar: Project Trident. I think that this is a real barrier to BSDs success. Linux succeeds because people can quickly and easily install it. Hopefully, MidnightBSD does that for BSD, but right now it has a long way to go. + +Have you ever used MidnightBSD? If not, what is your favorite BSD? What other BSD topics should we cover? 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][8]. + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/midnightbsd-1-0-release/ + +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://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/10/midnightbsd-wallpaper.jpeg +[2]: https://www.midnightbsd.org/ +[3]: https://www.midnightbsd.org/notes/ +[4]: https://itsfoss.com/what-is-zfs/ +[5]: https://man.openbsd.org/doas +[6]: https://twitter.com/midnightbsd +[7]: https://www.youtube.com/watch?v=-rlk2wFsjJ4 +[8]: http://reddit.com/r/linuxusersgroup diff --git a/sources/tech/20181018 TimelineJS- An interactive, JavaScript timeline building tool.md b/sources/tech/20181018 TimelineJS- An interactive, JavaScript timeline building tool.md new file mode 100644 index 0000000000..1f45811416 --- /dev/null +++ b/sources/tech/20181018 TimelineJS- An interactive, JavaScript timeline building tool.md @@ -0,0 +1,82 @@ +TimelineJS: An interactive, JavaScript timeline building tool +====== +Learn how to tell a story with TimelineJS. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/clocks_time.png?itok=_ID09GDk) + +[TimelineJS 3][1] is an open source storytelling tool that anyone can use to create visually rich, interactive timelines to post on their websites. To get started, simply click “Make a Timeline” on the homepage and follow the easy [step-by-step instructions][1]. + +TimelineJS was developed at Northwestern University’s KnightLab in Evanston, Illinois. KnightLab is a community of designers, developers, students, and educators who work on experiments designed to push journalism into new spaces. TimelineJS has been used by more than 250,000 people, according to its website, to tell stories viewed millions of times. And TimelineJS3 is available in more than 60 languages. + +Joe Germuska, the “chief nerd” who runs KnightLab’s technology, professional staff, and student fellows, explains, "TimelineJS was originally developed by Northwestern professor Zach Wise. He assigned his students a task to tell stories in a timeline format, only to find that none of the free available tools were as good as he thought they could be. KnightLab funded some of his time to develop the tool in 2012. Near the end of that year, I joined the lab, and among my early tasks was to bring TimelineJS in as a fully supported project of the lab. The next year, I helped Zach with a rewrite to address some issues. Along the way, many students have contributed. Interestingly, a group of students from Victoria University in Wellington, New Zealand, worked on TimelineJS (and some of our other tools) as part of a class project in 2016." + +"In general, we designed TimelineJS to make it easy for non-technical people to tell rich, dynamic stories on the web in the context of events in time.” + +Users create timelines by adding content into a Google spreadsheet. KnightLab provides a downloadable template that can be edited to create custom timelines. Experts can use their JSON skills to [create custom installations][2] while keeping TimelineJS’s core functionality. + +This easy-to-follow [Vimeo video][3] shows how to get started with TimelineJS, and I used it myself to create my first timeline. + +### Open sourcing the Adirondacks + +Reid Larson, research and scholarly communication librarian at Hamilton College in Clinton, New York, began searching for ways to combine open data and visualization to chronicle the history of Essex County (a county in northern New York that makes up part of the Adirondacks), in the 1990s, when he was the director of the Essex County Historical Society/Adirondack History Center Museum. + +"I wanted to take all the open data available on the history of Essex County and be able to present it to people visually. Most importantly, I wanted to make sure that the data would be available for use even if the applications used to present it are no longer available or supported," Larson explains. + +Now at Hamilton College, Larson has found TimelineJS to be the ideal open source program to do just what he wanted: Chronicle and present a visually appealing timeline of selected places. + +"It was a professor who was working on a project that required a solution such as Timeline, and after researching the possibilities, I started using Timeline for that project and subsequent projects," Larson adds. + +TimelineJS can be used via a web browser, or the source code can be downloaded from [GitHub][4] for local use. + +"I’ve been using the browser version, but I push it to the limits to see how far I can go with it, such as adding my own HTML tags. I want to fully understand it so that I can educate the students and faculty at Hamilton College on its uses," Larson says. + +### An open source Eagle Scout project + +Not only has Larson used TimelineJS for collegiate purposes, but his son, Erik, created an [interactive historical website][5] for his Eagle Scout project in 2017 using WordPress. The project is a chronicle of places in Waterville, New York, just south of Clinton, in Oneida County. Erik explains that he wants what he started to expand beyond the 36 places in Waterville. "The site is an experiment in online community building," Erik’s website reads. + +Larson says he did a lot of the “tech work” on the project so that Erik could concentrate on content. The site was created with [Omeka][6], an open source web publishing platform for sharing digital collections and creating media-rich online exhibits, and [Curatescape][7], a framework for the open source Omeka CMS. + +Larson explains that a key feature of TimelineJS is that it uses Google Sheets to store and organize the data used in the timeline. "Google Sheets is a good structure for organizing data simply, and that data will be available even if TimelineJS becomes unavailable in the future." + +Larson says that he prefers using [ArcGIS][8] over KnightLab’s StoryMap because it uses spreadsheets to store content, whereas [StoryMap][9] does not. Larson is looking forward to integrating augmented reality into his projects in the future. + +### Create your own open source timeline + +I plan on using TimelineJS to create interactive content for the Development and Alumni Relations department at Clarkson University, where I am the development communications specialist. To practice with working with it, I created [a simple timeline][10] of the articles I’ve written for [Opensource.com][11]: + +![](https://opensource.com/sites/default/files/uploads/google-sheet-timeline.png) +![](https://opensource.com/sites/default/files/uploads/wordpress-timeline.png) + +![](https://opensource.com/sites/default/files/uploads/website-timeline.png) + +As Reid Larson stated, it is very easy to use and the results are quite satisfactory. I was able to get a working timeline created and posted to my WordPress site in a matter of minutes. I used media that I had already uploaded to my Media Library in WordPress and simply copied the image address. I typed in the dates, locations, and information in the other cells and used “publish to web” under “file” in the Google spreadsheet. That produced a link and embed code. I created a new post in my WordPress site and pasted in the embed code, and the timeline was live and working. + +Of course, there is more customization I need to do, but I was able to get it working quickly and easily, much as Reid said it would. + +I will continue experimenting with TimelineJS on my own site, and when I get more comfortable with it, I’ll use it for my professional projects and try out the other apps that KnightLab has created for interactive, visually appealing storytelling. + +What might you use TimelineJS for? + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/10/create-interactive-timelines-open-source-tool + +作者：[Jeff Macharyas][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/rikki-endsley +[b]: https://github.com/lujun9972 +[1]: https://timeline.knightlab.com/ +[2]: https://timeline.knightlab.com/docs/json-format.html +[3]: https://vimeo.com/knightlab/timelinejs +[4]: https://github.com/NUKnightLab/TimelineJS3 +[5]: http://nysplaces.com/ +[6]: https://github.com/omeka +[7]: https://github.com/CPHDH/Curatescape +[8]: https://www.arcgis.com/index.html +[9]: https://storymap.knightlab.com/ +[10]: https://macharyas.com/index.php/2018/10/06/timeline/ +[11]: http://opensource.com/ diff --git a/translated/tech/20180615 Complete Sed Command Guide [Explained with Practical Examples].md b/translated/tech/20180615 Complete Sed Command Guide [Explained with Practical Examples].md new file mode 100644 index 0000000000..558663de0d --- /dev/null +++ b/translated/tech/20180615 Complete Sed Command Guide [Explained with Practical Examples].md @@ -0,0 +1,1029 @@ +Sed 命令完全指南 +====== +在前面的文章中，我展示了 [Sed 命令的基本用法][1]，它是一个功能强大的流编辑器。今天，我们准备去了解关于 Sed 更多的知识，深入了解 Sed 的运行模式。这将是你全面了解 Sed 命令的一个机会，深入挖掘它的运行细节和精妙之处。因此，如果你已经做好了准备，那就打开终端吧，[下载测试文件][2] 然后坐在电脑前：开始我们的探索之旅吧！ + +### 关于 Sed 的一点点理论知识 + +![complete reference guide to sed commands][4] + +#### 首先我们看一下 sed 的运行模式 + +要准确理解 Sed 命令，你必须先了解工具的运行模式。 + +当处理数据时，Sed 从输入源一次读入一行，并将它保存到所谓的 `pattern` 空间中。所有 Sed 的变动都发生在 `pattern` 空间。变动都是由命令行上或外部 Sed 脚本文件提供的单字母命令来描述的。大多数 Sed 命令都可以由一个地址或一个地址范围作为前导来限制它们的作用范围。 + +默认情况下，Sed 在结束每个处理循环后输出 `pattern` 空间中的内容，也就是说，输出发生在输入的下一个行覆盖 `pattern` 空间之前。我们可以将这种运行模式总结如下： + + 1. 尝试将下一个行读入到 `pattern` 空间中 + + 2. 如果读取成功： + + 1. 按脚本中的顺序将所有命令应用到与那个地址匹配的当前输入行上 + + 2. 如果 sed 没有以静默（`-n`）模式运行，那么将输出 `pattern` 空间中的所有内容（可能会是修改过的）。 + + 3. 重新回到 1。 + + + + +因此，在每个行被处理完毕之后， `pattern` 空间中的内容将被丢弃，它并不适合长时间保存内容。基于这种目的，Sed 有第二个缓冲区：`hold` 空间。除非你显式地要求它将数据置入到 `hold` 空间、或从`hode` 空间中取得数据，否则 Sed 从不清除 `hold` 空间的内容。在我们后面学习到 `exchange`、`get`、`hold` 命令时将深入研究它。 + +#### Sed 的抽象机制 + +你将在许多的 Sed 教程中都会看到上面解释的模式。的确，这是充分正确理解大多数基本 Sed 程序所必需的。但是当你深入研究更多的高级命令时，你将会发现，仅这些知识还是不够的。因此，我们现在尝试去了解更深入的一些知识。 + +的确，Sed 可以被视为是[抽象机制][5]的实现，它的[状态][6]由三个[缓冲区][7] 、两个[寄存器][8]和两个[标志][9]来定义的： + + * **三个缓冲区**用于去保存任意长度的文本。是的，是三个！在前面的基本运行模式中我们谈到了两个： `pattern` 空间和 `hold` 空间，但是 Sed 还有第三个缓冲区：追加队列。从 Sed 脚本的角度来看，它是一个只写缓冲区，Sed 将在它运行时的预定义阶段来自动刷新它（一般是在从输入源读入一个新行之前，或仅在它退出运行之前）。 + + * Sed 也维护**两个寄存器**：行计数器（LC）用于保存从输入源读取的行数，而程序计数器（PC）总是用来保存下一个将要运行的命令的索引（就是脚本中的位置），Sed 将它作为它的主循环的一部分来自动增加 PC。但在使用特定的命令时，脚本也会直接修改 PC 去跳过或重复程序的一部分。这就像使用 Sed 实现的一个循环或条件语句。更多内容将在下面的专用分支一节中描述。 + + * 最后，**两个标志**可以被某些 Sed 命令的行为所修改：自动输出（AP）标志和替换标志（SF）。当自动输出标志 AP 被设置时，Sed 将在 `pattern` 空间的内容被覆盖前自动输出（尤其是（包括但不限于）在从输入源读入一个新行之前）。当自动输出标准被清除时（即：没有设置），Sed 在脚本中没有显式命令的情况下，将不会输出 `pattern` 空间中的内容。你可以通过在“静默模式”（使用命令行选项 `-n` 或者在第一行或脚本中使用特殊注释 `#n`）运行 Sed 命令来清除自动输出标志。当它的地址和查找模式与 `pattern` 空间中的内容都匹配时，“替换标志”将被替换命令（`s` 命令）设置。替换标志在每个新的循环开始时、或当从输入源读入一个新行时、或获得条件分支之后将被清除。我们将在分支一节中详细研究这一话题。 + + + + +另外，Sed 维护一个进入到它的地址范围（关于地址范围的更多知识将在地址范围一节详细描述）的命令列表，以及用于读取和写入数据的两个文件句柄（你将在读取和写入命令的描述中获得更多有关文件句柄的内容）。 + +#### 一个更精确的 Sed 运行模式 + +由于一张图胜过千言万语，所以我画了一个流程图去描述 Sed 的运行模式。我将两个东西放在了旁边，像处理多个输入文件或错误处理，但是我认为这足够你去理解任何 Sed 程序的行为了，并且可以避免你在编写你自己的 Sed 脚本时浪费在摸索上的时间。 + +![The Sed execution model][10] + +你可能已经注意到，在上面的流程图上我并没有描述特定的命令动作。对于命令，我们将逐个详细讲解。因此，不用着急，我们马上开始！ + +### print 命令 + +print 命令（`p`）是用于输出在它运行时 `pattern` 空间中的内容。它并不会以任何方式改变 Sed 抽象机制中的状态。 + +![The Sed `print` command][11] + +示例： +``` +sed -e 'p' inputfile + +``` + +上面的命令将输出输入文件中每一行的内容两次，因为你一旦显式地要求使用 `print` 命令时，将会在每个处理循环结束时再隐式地输出一次（因为在这里我们不是在“静默模式”中运行 Sed）。 + +如果我们不想每个行看到两次，我们可以用两种方式去解决它： +``` +sed -n -e 'p' inputfile # 在静默模式中显式输出 +sed -e '' inputfile # 空的"什么都不做的"程序，隐式输出 + +``` + +注意：`-e` 选项是引入一个 Sed 命令。它被用于区分命令和文件名。由于一个 Sed 表达式必须包含至少一个命令，所以对于第一个命令，`-e` 标志不是必需的。但是，由于我个人使用习惯问题，为了与在这里的大多数的一个命令行上给出多个 Sed 表达式的更复杂的案例保持一致性。你自己去判断这是一个好习惯还是坏习惯，并且在本文的后面部分还将延用这一习惯。 + +### 地址 + +显而易见，`print` 命令本身并没有太多的用处。但是，如果你在它之前添加一个地址，这样它就只输出输入文件的一些行，这样它就突然变得能够从一个输入文件中过滤一些不希望的行。那么 Sed 的地址又是什么呢？它是如何来辨别输入文件的“行”呢？ + +#### 行号 + +一个 Sed 的地址既可以是一个行号（`$` 表示“最后一行”）也可以是一个正则表达式。在使用行号时，你需要记住 Sed 中的行数是从 1 开始的 — 并且需要注意的是，它不是从 0 行开始的。 +``` +sed -n -e '1p' inputfile # 仅输出文件的第一行 +sed -n -e '5p' inputfile # 仅输出第 5 行 +sed -n -e '$p' inputfile # 输出文件的最后一行 +sed -n -e '0p' inputfile # 结果将是报错，因为 0 不是有效的行号 + +``` + +根据 [POSIX 规范][12]，如果你指定了几个输出文件，那么它的行号是累加的。换句话说，当 Sed 打开一个新输入文件时，它的行计数器是不会被重置的。因此，以下的两个命令所做的事情是一样的。仅输出一行文本： +``` +sed -n -e '1p' inputfile1 inputfile2 inputfile3 +cat inputfile1 inputfile2 inputfile3 | sed -n -e '1p' + +``` + +实际上，确实在 POSIX 中规定了多个文件是如何处理的： + +> 如果指定了多个文件，将按指定的文件命名顺序进行读取并被串联编辑。 + +但是，一些 Sed 的实现提供了命令行选项去改变这种行为，比如， GNU Sed 的 `-s` 标志（在使用 GNU Sed `-i` 标志时，它也被隐式地应用）： +``` +sed -sn -e '1p' inputfile1 inputfile2 inputfile3 + +``` + +如果你的 Sed 实现支持这种非标准选项，那么关于它的具体细节请查看 `man` 手册页。 + +#### 正则表达式 + +我前面说过，Sed 地址既可以是行号也可以是正则表达式。那么正则表达式是什么呢？ + +正如它的名字，一个[正则表达式][13]是描述一个字符串集合的方法。如果一个指定的字符串符合一个正则表达式所描述的集合，那么我们就认为这个字符串与正则表达式匹配。 + +一个正则表达式也可以包含必须完全匹配的文本字符。例如，所有的字母和数字，以及大部分可以打印的字符。但是，一些符号有特定意义： + + * 它们可能相当于锚，像 `^` 和 `$` 它们分别表示一个行的开始和结束； + + * 对于整个字符集，另外的符号可能做为占位符（比如圆点 `.` 可以匹配任意单个字符，或者方括号用于定义一个自定义的字符集）； + + * 另外的是表示重复出现的数量（像 [Kleene 星号][14] 表示前面的模式出现 0、1 或多次）； + + + + +这篇文章的目的不是给大家讲正则表达式。因此，我只粘几个示例。但是，你可以在网络上随便找到很多关于正则表达式的教程，正则表达式的功能非常强大，它可用于许多标准的 Unix 命令和编程语言中，并且是每个 Unix 用户应该掌握的技能。 + +下面是使用 Sed 地址的几个示例： +``` +sed -n -e '/systemd/p' inputfile # 仅输出包含字符串"systemd"的行 +sed -n -e '/nologin$/p' inputfile # 仅输出以"nologin"结尾的行 +sed -n -e '/^bin/p' inputfile # 仅输出以"bin"开头的行 +sed -n -e '/^$/p' inputfile # 仅输出空行（即：开始和结束之间什么都没有的行） +sed -n -e '/./p' inputfile # 仅输出包含一个字符的行(即：非空行) +sed -n -e '/^.$/p' inputfile # 仅输出确实只包含一个字符的行 +sed -n -e '/admin.*false/p' inputfile # 仅输出包含字符串"admin"后面有字符串"false"的行(在它们之间有任意数量的任意字符) +sed -n -e '/1[0,3]/p' inputfile # 仅输出包含一个"1"并且后面是一个"0"或"3"的行 +sed -n -e '/1[0-2]/p' inputfile # 仅输出包含一个"1"并且后面是一个"0"、"1"、"2"或"3"的行 +sed -n -e '/1.*2/p' inputfile # 仅输出包含字符"1"后面是一个"2"(在它们之间有任意数量的字符)的行 +sed -n -e '/1[0-9]*2/p' inputfile # 仅输出包含字符"1"后面跟着0、1、或更多数字，最后面是一个"2"的行 + +``` + +如果你想在正则表达式（包括正则表达式分隔符）中去除字符的特殊意义，你可以在它前面使用一个斜杠： +``` +# 输出所有包含字符串"/usr/sbin/nologin"的行 +sed -ne '/\/usr\/sbin\/nologin/p' inputfile + +``` + +并不是限制你只能使用反斜杠作为地址中正则表达式的分隔符。你可以通过在第一个分隔符前面加上斜杠的方式，来使用任何你认为适合你需要和偏好的其它字符作为正则表达式的分隔符。当你用地址与带文件路径的字符一起来匹配的时，是非常有用的： +``` +# 以下两个命令是完全相同的 +sed -ne '/\/usr\/sbin\/nologin/p' inputfile +sed -ne '\=/usr/sbin/nologin=p' inputfile + +``` + +#### 扩展的正则表达式 + +默认情况下，Sed 的正则表达式引擎仅理解 [POSIX 基本正则表达式][15] 的语法。如果你需要用到 [扩展的正则表达式][16]，你必须在 Sed 命令上添加 `-E` 标志。扩展的正则表达式在基本的正则表达式基础上增加了一组额外的特性，并且很多都是很重要的，他们所要求的斜杠要少很多。我们来比较一下： +``` +sed -n -e '/\(www\)\|\(mail\)/p' inputfile +sed -En -e '/(www)|(mail)/p' inputfile + +``` + +#### 括号量词 + +正则表达式之所以强大的一个原因是[范围量词][17]`{,}`。事实上，当你写一个不太精确匹配的正则表达式时，量词 `*` 就是一个非常完美的符号。但是，你需要显式在它边上添加一个下限和上限，这样就有了很好的灵活性。当量词范围的下限省略时，下限被假定为 0。当上限被省略时，上限被假定为无限大： + +|括号| 速记词 |解释| + +| {,} | * | 前面的规则出现 0、1、或许多遍 | +| {,1} | ? | 前面的规则出现 0 或 1 遍 | +| {1,} | + | 前面的规则出现 1 或许多遍 | +| {n,n} | {n} | 前面的规则精确地出现 n 遍 | + +括号在基本的正则表达式中也是可以使用的，但是它要求使用反斜杠。根据 POSIX 规范，在基本的正则表达式中可以使用的量词仅有星号（`*`）和括号（使用反斜杠 `\{m,n\}`）。许多正则表达式引擎都扩展支持 `\?` 和 `\+`。但是，为什么魔鬼如此有诱惑力呢？因为，如果你需要这些量词，使用扩展的正则表达式将不但易于写而且可移植性更好。 + +为什么我要花点时间去讨论关于正则表达式的括号量词，这是因为在 Sed 脚本中经常用这个特性去计数字符。 +``` +sed -En -e '/^.{35}$/p' inputfile # 输出精确包含 35 个字符的行 +sed -En -e '/^.{0,35}$/p' inputfile # 输出包含 35 个字符或更少字符的行 +sed -En -e '/^.{,35}$/p' inputfile # 输出包含 35 个字符或更少字符的行 +sed -En -e '/^.{35,}$/p' inputfile # 输出包含 35 个字符或更多字符的行 +sed -En -e '/.{35}/p' inputfile # 你自己指出它的输出内容（这是留给你的测试题） + +``` + +#### 地址范围 + +到目前为止，我们使用的所有地址都是唯一地址。在我们使用一个唯一地址时，命令是应用在与那个地址匹配的行上。但是，Sed 也支持地址范围。Sed 命令可以应用到那个地址范围中从开始到结束的所有地址中的所有行上： +``` +sed -n -e '1,5p' inputfile # 仅输出 1 到 5 行 +sed -n -e '5,$p' inputfile # 从第 5 行输出到文件结尾 + +sed -n -e '/www/,/systemd/p' inputfile # 输出与正则表达式 /www/ 匹配的第一行到与正则表达式 /systemd/ 匹配的接下来的行 + +``` + +如果在开始和结束地址上使用了同一个行号，那么范围就缩小为那个行。事实上，如果第二个地址的数字小于或等于地址范围中选定的第一个行的数字，那么仅有一个行被选定： +``` +printf "%s\n" {a,b,c}{d,e,f} | cat -n | sed -ne '4,4p' + 4 bd +printf "%s\n" {a,b,c}{d,e,f} | cat -n | sed -ne '4,3p' + 4 bd + +``` + +这就有点难了，但是在前面的段落中给出的规则也适用于起始地址是正则表达式的情况。在那种情况下，Sed 将对正则表达式匹配的第一个行的行号和给定的作为结束地址的显式的行号进行比较。再强调一次，如果结束行号小于或等于起始行号，那么这个范围将缩小为一行： +``` +# 这个 /b/,4 地址将匹配三个单行 +# 因为每个匹配的行有一个行号 >= 4 +printf "%s\n" {a,b,c}{d,e,f} | cat -n | sed -ne '/b/,4p' + 4 bd + 5 be + 6 bf + +# 你自己指出匹配的范围是多少 +# 第二个例子： +printf "%s\n" {a,b,c}{d,e,f} | cat -n | sed -ne '/d/,4p' + 1 ad + 2 ae + 3 af + 4 bd + 7 cd + +``` + +但是，当结束地址是一个正则表达式时，Sed 的行为将不一样。在那种情况下，地址范围的第一行将不会与结束地址进行检查，因此地址范围将至少包含两行（当然，如果输入数据不足的情况除外）： +``` +printf "%s\n" {a,b,c}{d,e,f} | cat -n | sed -ne '/b/,/d/p' + 4 bd + 5 be + 6 bf + 7 cd + +printf "%s\n" {a,b,c}{d,e,f} | cat -n | sed -ne '4,/d/p' + 4 bd + 5 be + 6 bf + 7 cd + +``` + +#### 互补 + +在一个地址选择行后面添加一个感叹号（`!`）表示不匹配那个地址。例如： +``` +sed -n -e '5!p' inputfile # 输出除了第 5 行外的所有行 +sed -n -e '5,10!p' inputfile # 输出除了第 5 到 10 之间的所有行 +sed -n -e '/sys/!p' inputfile # 输出除了包含字符串"sys"的所有行 + +``` + +#### 连接 + +Sed 允许在一个块中使用括号 (`{…}`) 组合命令。你可以利用这个特性去组合几个地址。例如，我们来比较下面两个命令的输出： +``` +sed -n -e '/usb/{ +/daemon/p +}' inputfile + +sed -n -e '/usb.*daemon/p' inputfile + +``` + +通过在一个块中嵌套命令，我们将在任意顺序中选择包含字符串 “usb” 和 “daemon” 的行。而正则表达式 “usb.*daemon” 将仅匹配在字符串 “daemon” 前面包含 “usb” 字符串的行。 + +离题太长时间后，我们现在重新回去学习各种 Sed 命令。 + +### quit 命令 + +quit 命令（`q`）是指在当前的迭代循环处理结束之后停止 Sed。 + +![The Sed `quit` command][18] + +quit 命令是在到达输入文件的尾部之前停止处理输入的方法。为什么会有人想去那样做呢？ + +很好的问题，如果你还记得，我们可以使用下面的命令来输出文件中第 1 到第 5 的行： +``` +sed -n -e '1,5p' inputfile + +``` + +对于 大多数 Sed 的实现，工具将循环读取输入文件的所有行，那怕是你只处理结果中的前 5 行。如果你的输入文件包含了几百万行（或者更糟糕的情况是，你从一个无限的数据流（比如像 `/dev/urandom` ）中读取）。 + +使用 quit 命令，相同的程序可以被修改的更高效： +``` +sed -e '5q' inputfile + +``` + +由于我在这里并不使用 `-n` 选项，Sed 将在每个循环结束后隐式输出 `pattern` 空间的内容。但是在你处理完第 5 行后，它将退出，并且因此不会去读取更多的数据。 + +我们能够使用一个类似的技巧只输出文件中一个特定的行。那将是一个好机会，你将看到从命令行中提供多个 Sed 表达式的几种方法。下面的三个变体都可以从 Sed 中接受命令，要么是不同的 `-e` 选项，要么是在相同的表达式中新起一行或用分号（`;`）隔开： +``` +sed -n -e '5p' -e '5q' inputfile + +sed -n -e ' + 5p + 5q +' inputfile + +sed -n -e '5p;5q' inputfile + +``` + +如果你还记得，我们在前面看到过能够使用括号将命令组合起来，在这里我们使用它来防止相同的地址重复两次： +``` +# 组合命令 +sed -e '5{ + p + q +}' inputfile + +# Which can be shortened as: +sed '5{p;q;}' inputfile + +# As a POSIX extension, some implementations makes the semi-colon before the closing bracket optional: +sed '5{p;q}' inputfile + +``` + +### substitution 命令 + +你可以将替换命令想像为 Sed 的“查找替换”功能，这个功能在大多数的“所见即所得”的编辑器上都能找到。Sed 的替换命令与之类似，但比它们更强大。替换命令是 Sed 中最著名的命令之一，在网上有大量的关于这个命令的文档。 + +![The Sed `substitution` command][19] + +[在前一篇文章][20]中我们已经讲过它了，因此，在这里就不再重复了。但是，如果你对它的使用不是很熟悉，那么你需要记住下面的这些关键点： + + * 替换命令有两个参数：查找模式和替换字符串：`sed s/:/-----/ inputfile` + + * 命令和它的参数是用任意一个字符来分隔的。这主要看你的习惯，在 99% 的时间中我都使用斜杠，但也会用其它的字符：`sed s%:%-----% inputfile`、`sed sX:X-----X inputfile` 或者甚至是 `sed 's : ----- ' inputfile` + + * 默认情况下，替换命令仅被应用到 `pattern` 空间中匹配到的第一个字符串上。你可以通过在命令之后指定一个匹配指数作为标志来改变这种情况：`sed 's/:/-----/1' inputfile`、`sed 's/:/-----/2' inputfile`、`sed 's/:/-----/3' inputfile`、… + + * 如果你想执行一个全面的替换（即：在 `pattern` 空间上的每个非重叠匹配），你需要增加 `g` 标志：`sed 's/:/-----/g' inputfile` + + * 在字符串替换中，出现的任何一个 `&` 符号都将被与查找模式匹配的子字符串替换：`sed 's/:/-&&&-/g' inputfile`、`sed 's/…./& /g' inputfile` + + * 圆括号（在扩展的正则表达式中的 `(…)` 或者基本的正则表达式中的 `\(…\)`）被引用为捕获组。那是匹配字符串的一部分，可以在替换字符串中被引用。`\1` 是第一个捕获组的内容，`\2` 是第二个捕获组的内容，依次类推：`sed -E 's/(.)(.)/\2\1/g' inputfile`、`sed -E 's/(.):x:(.):(.*)/\1:\3/' inputfile`（后者之所能正常工作是因为 [正则表达式中的量词星号表示重复匹配下去，直到不匹配为止][21]，并且它可以匹配许多个字符） + + * 在查找模式或替换字符串时，你可以通过使用一个反斜杠来去除任何字符的特殊意义：`sed 's/:/--\&--/g' inputfile`，`sed 's/\//\\/g' inputfile` + + + + +所有的这些看起来有点抽象，下面是一些示例。首先，我想去显示我的测试输入文件的第一个字段并给它在右侧附加 20 个空格字符，我可以这样写： +``` +sed < inputfile -E -e ' + s/:/ / # 用 20 个空格替换第一个字段的分隔符 + s/(.{20}).*/\1/ # 只保留一行的前 20 个字符 + s/.*/| & |/ # 为了输出好看添加竖条 +' + +``` + +第二个示例是，如果我想将用户 sonia 的 UID/GID 修改为 1100，我可以这样写： +``` +sed -En -e ' + /sonia/{ + s/[0-9]+/1100/g + p + }' inputfile + +``` + +注意在替换命令结束部分的 `g` 选项。这个选项改变了它的行为，因此它将查找全部的 `pattern` 空间并替换，如果没有那个选项，它只替换查找到的第一个。 + +顺便说一下，这也是使用前面讲过的输出（`p`）命令的好机会，可以在命令运行时输出修改前后时刻 `pattern` 空间的内容。因此，为了获得替换前后的内容，我可以这样写： +``` +sed -En -e ' + /sonia/{ + p + s/[0-9]+/1100/g + p + }' inputfile + +``` + +事实上，替换后输出一个行是很常见的用法，因此，替换命令也接受 `p` 选项： +``` +sed -En -e '/sonia/s/[0-9]+/1100/gp' inputfile + +``` + +最后，我就不详细讲替换命令的 `w` 选项了，我们将在稍后的学习中详细介绍。 + +#### delete 命令 + +删除命令（`d`）用于清除 `pattern` 空间的内容，然后立即开始下一个处理循环。这样它将会跳过隐式输出 `pattern` 空间内容的行为，即便是你设置了自动输出标志（AP）也不会输出。 + +![The Sed `delete` command][22] + +只输出一个文件前五行的一个很低效率的方法将是： +``` +sed -e '6,$d' inputfile + +``` + +你猜猜看，我为什么说它很低效率？如果你猜不到，建议你再次去阅读前面的关于 quit 命令的章节，答案就在那里！ + +当你组合使用正则表达式和地址，从输出中删除匹配的行时，delete 命令将非常有用： +``` +sed -e '/systemd/d' inputfile + +``` + +#### next 命令 + +如果 Sed 命令不是在静默模式中运行，这个命令将输出当前 `pattern` 空间的内容，然后，在任何情况下它将读取下一个输入行到 `pattern` 空间中，并使用新的 `pattern` 空间中的内容来运行当前循环中剩余的命令。 + +![The Sed `next` command][23] + +常见的用 next 命令去跳过行的一个示例： +``` +cat -n inputfile | sed -n -e 'n;n;p' + +``` + +在上面的例子中，Sed 将隐式地读取输入文件的第一行。但是 `next` 命令将丢弃对 `pattern` 空间中的内容的输出（不输出是因为使用了 `-n` 选项），并从输入文件中读取下一行来替换 `pattern` 空间中的内容。而第二个 `next` 命令做的事情和前一个是一模一样的，这就实现了跳过输入文件 2 行的目的。最后，这个脚本显式地输出包含在 `pattern ` 空间中的输入文件的第三行的内容。然后，Sed 将启动一个新的循环，由于 `next` 命令，它会隐式地读取第 4 行的内容，然后跳过它，同样地也跳过第 5 行，并输出第 6 行。如此循环，直到文件结束。总体来看，这个脚本就是读取输入文件然后每三行输出一行。 + +使用 next 命令，我们也可以找到一些显示输入文件的前五行的几种方法： +``` +cat -n inputfile | sed -n -e '1{p;n;p;n;p;n;p;n;p}' +cat -n inputfile | sed -n -e 'p;n;p;n;p;n;p;n;p;q' +cat -n inputfile | sed -e 'n;n;n;n;q' + +``` + +更有趣的是，如果你需要根据一些地址来处理行时，next 命令也非常有用： +``` +cat -n inputfile | sed -n '/pulse/p' # 输出包含 "pulse" 的行 +cat -n inputfile | sed -n '/pulse/{n;p}' # 输出包含 "pulse" 之后的行 +cat -n inputfile | sed -n '/pulse/{n;n;p}' # 输出下面的行 + # 下一行 + # 包含 "pulse" 的行 + +``` + +### 使用 `hold` 空间 + +到目前为止，我们所看到的命令都是仅使用了 `pattern` 空间。但是，我们在文章的开始部分已经提到过，还有第二个缓冲区：`hold` 空间，它完全由用户管理。它就是我们在第二节中描述的目标。 + +#### exchange 命令 + +正如它的名字所表示的，exchange 命令（`x`）将交换 `hold` 空间和 `pattern` 空间的内容。记住，你只要没有把任何东西放入到 `hold` 空间中，那么 `hold` 空间就是空的。 + +![The Sed `exchange` command][24] + +作为第一个示例，我们可使用 exchange 命令去反序输出一个输入文件的前两行： +``` +cat -n inputfile | sed -n -e 'x;n;p;x;p;q' + +``` + +当然，在你设置 `hold` 之后你并没有立即使用它的内容，因为只要你没有显式地去修改它， `hold` 空间中的内容就保持不变。在下面的例子中，我在输入一个文件的前五行后，使用它去删除第一行： +``` +cat -n inputfile | sed -n -e ' + 1{x;n} # 交换 hold 和 pattern 空间 + # 保存第 1 行到 hold 空间中 + # 然后读取第 2 行 + 5{ + p # 输出第 5 行 + x # 交换 hold 和 pattern 空间 + # 去取得第 1 行的内容放回到 + # pattern 空间 + } + + 1,5p # 输出第 2 到第 5 行 + # (不要输错了！尝试找出这个规则 + # 没有在第 1 行上运行的原因;) +' + +``` + +#### hold 命令 + +hold 命令（`h`）是用于将 `pattern` 空间中的内容保存到 `hold` 空间中。但是，与 exchange 命令不同的是，`pattern` 空间中的内容不会被改变。hold 命令有两种用法： + + * `h` +将复制 `pattern` 空间中的内容到 `hold` 空间中，将覆盖 `hold` 空间中任何已经存在的内容。 + + * `H` +使用一个独立的新行，追加 `pattern` 空间中的内容到 `hold` 空间中。 + + + + +![The Sed `hold` command][25] + +上面使用 exchange 命令的例子可以使用 hold 命令重写如下： +``` +cat -n inputfile | sed -n -e ' + 1{h;n} # 保存第 1 行的内容到 hold 缓冲区并继续 + 5{ # 到第 5 行 + x # 交换 pattern 和 hold 空间 + # (现在 pattern 空间包含了第 1 行) + H # 在 hold 空间的第 5 行后追回第 1 行 + x # 再次交换取回第 5 行并将第 1 行插入 + # 到 pattern 空间 + } + + 1,5p # 输出第 2 行到第 5 行 + # (不要输错！尝试去打到为什么这个规则 + # 不在第 1 行上运行;) +' + +``` + +#### get 命令 + +get 命令（`g`）与 hold 命令恰好相反：它从 `hold` 空间中取得内容并将它置入到 `pattern` 空间中。同样它也有两种方式： + + * `g` +它将复制 `hold` 空间中的内容并将其放入到 `pattern` 空间，覆盖 `pattern`空间中已存在的任何内容 + + * `G` +使用一个单独的新行，追加 `hold` 空间中的内容到 `pattern` 空间中 + + + + +![The Sed `get` command][26] + +将 hold 命令和 get 命令一起使用，可以允许你去存储并调回数据。作为一个小挑战，我让你重写前一节中的示例，将输入文件的第 1 行放置在第 5 行之后，但是这次必须使用 get 和 hold 命令（注意大小写）而不能使用 exchange 命令。只要运气好，它将使那个方式更简单！ + +在这期间，我可以给你展示另一个示例，它能给你一些灵感。目标是将拥有登录 shell 权限的用户与其它用户分开： +``` +cat -n inputfile | sed -En -e ' + \=(/usr/sbin/nologin|/bin/false)$= { H;d; } + # 追回匹配的行到 hold 空间 + # 然后继续下一个循环 + p # 输出其它行 + $ { g;p } # 在最后一行上 + # 取得并输出 hold 空间中的内容 +' + +``` + +### 复习 print、delete 和 next + +现在你已经更熟悉使用 hold 空间了，我们回到 print、delete 和 next 命令。我们已经讨论了小写的 `p`、`d` 和 `n` 命令了。而它们也有大写的版本。因为每个命令都有大小写版本，似乎是 Sed 的习惯，这些命令的大写版本将与多行缓冲区有关： + + * `P` +将 `pattern` 空间中第一个新行之前的内容输出 + + * `D` +删除 `pattern` 空间中的内容并且包含新行，然后不读取任何新的输入而是使用剩余的文本去重启一个循环 + + * `N` +使用一个换行符作为新旧数据的分隔符，然后读取并追加一个输入的新行到 `pattern` 空间。继续运行当前的循环。 + + + + +![The Sed uppercase `Delete` command][27] +![The Sed uppercase `Next` command][28] + +这些命令的使用场景主要用于实现队列（[FIFO 列表][29]）。从一个输入文件中删除最后 5 行就是一个很权威的例子： +``` +cat -n inputfile | sed -En -e ' + 1 { N;N;N;N } # 确保 pattern 空间中包含 5 行 + + N # 追加第 6 行到队列中 + P # 输出队列的第 1 行 + D # 删除队列的第 1 行 +' + +``` + +作为第二个示例，我们可以在两个列上显示输入数据： +``` +# 输出两列 +sed < inputfile -En -e ' + $!N # 追加一个新行到 pattern 空间 + # 除了输入文件的最后一行 + # 当在输入文件的最后一行使用 N 命令时 + # GNU Sed 和 POSIX Sed 的行为是有差异的 + # 需要使用一个技巧去处理这种情况 + # https://www.gnu.org/software/sed/manual/sed.html#N_005fcommand_005flast_005fline + + # 用空间填充第 1 行的第 1 个字段 + # 并丢弃其余行 + s/:.*\n/ \n/ + s/:.*// # 除了第 2 行上的第 1 个字段外，丢弃其余的行 + s/(.{20}).*\n/\1/ # 修剪并连接行 + p # 输出结果 +' + +``` + +### 分支 + +我们刚才已经看到，Sed 因为有 `hold` 空间所以有了缓存的功能。其实它还有测试和分支的指令。因为有这些特性使得 Sed 是一个[图灵完备][30]的语言。虽然它可能看起来很傻，但意味着你可以使用 Sed 写任何程序。你可以实现任何你的目的，但并不意味着实现起来会很容易，而且结果也不一定会很高效。 + +但是，不用担心。在本文中，我们将使用能够展示测试和分支功能的最简单的例子。虽然这些功能乍一看似乎很有限，但请记住，有些人用 Sed 写了 [calculators]、 [Tetris] 或许多其它类型的应用程序！ + +#### 标签和分支 + +从某些方面，你可以将 Sed 看到是一个功能有限的汇编语言。因此，你不会找到在高级语言中常见的 “for” 或 “while” 循环，或者 “if … else” 语句，但是你可以使用分支来实现同样的功能。 + +![The Sed `branch` command][31] + +如果你在本文开始部分看到了用流程图描述的 Sed 运行模型，那么你应该知道 Sed 会自动增加程序计数器的值，命令是按程序的指令顺序来运行的。但是，使用分支指令，你可以通过选择程序中的任意命令来改变顺序运行的程序。跳转目的地是使用一个标签来显式定义的。 + +![The Sed `label` command][32] + +这是一个这样的示例： +``` +echo hello | sed -ne ' + :start # 在程序的那个行上放置一个 "start" 标签 + p # 输出 pattern 空间内容 + b start # 继续在 :start 标签上运行 +' | less + +``` + +那个 Sed 程序的行为非常类似于 `yes` 命令：它获取一个流并产生一个包含那个字符串的无限流。 + +切换到一个标签就像我们旁通了 Sed 的自动化特性一样：它既不读取任何输入，也不输出任何内容，更不更新任何缓冲区。它只是跳转到一个不同于源程序指令顺序的另一个指令。 + +值得一提的是，如果在分支命令（`b`）上没有指定一个标签作为它的参数，那么分支将直接切换到程序结束的地方。因此，Sed 将启动一个新的循环。这个特性可以用于去旁通一些指令并且因此可以用于作为块的替代者： +``` +cat -n inputfile | sed -ne ' +/usb/!b +/daemon/!b +p +' + +``` + +#### 条件分支 + +到目前为止，我们已经看到了无条件分支，这个术语可能有点误导嫌疑，因为 Sed 命令总是基于它们的可选地址来作为条件的。 + +但是，在传统意义上，一个无条件分支也是一个分支，当它运行时，将跳转到特定的目的地，而条件分支既有可能也或许不可能跳转到特定的指令，这取决于系统的当前状态。 + +Sed 只有一个条件指令，就是 test（`t`） 命令。只有在当前循环的开始或因为前一个条件分支运行了替换，它才跳转到不同的指令。更多的情况是，只有替换标志被设置时，test 命令才会切换。 + +![The Sed `test` command][3]![The Sed `test` command][33] + +使用 test 指令，你可以在一个 Sed 程序中很轻松地执行一个循环。作为一个特定的示例，你可以用它将一个行填充到某个长度（这是使用正则表达式无法实现的）： +``` +# Center text +cut -d: -f1 inputfile | sed -Ee ' + :start + s/^(.{,19})$/ \1 / # 用空格在开始处填充少于 20 个字符的行 + # 并在结束处 + # 添加一个空格 + t start # 如果我们已经添加了一个空格，则返回到 :start 标签 + s/(.{20}).*/| \1 |/ # 保留一个行的前 20 个字符 + # 以修复由于奇数行引起的 + # 差一错误 +' + +``` + +如果你仔细读前面的示例，你可能注意到，在将要把数据“喂”给 Sed 之前，我会通过使用 cut 命令创建一个比特去预处理数据。 + +然后，我们可以只使用 Sed 对程序做一些小的修改来执行相同的任务： +``` +cat inputfile | sed -Ee ' + s/:.*// # 除第 1 个字段外删除剩余字段 + t start + :start + s/^(.{,19})$/ \1 / # 在开始处使用空格去填充 + # 并在结束处填充一个空格 + # 使行的长度不短于 20 个字符 + t start # 如果添加了一个空格，则返回到 :start + s/(.{20}).*/| \1 |/ # 仅保留一个行的前 20 个字符 + # 以修复由于奇数行引起的 + # 差一错误 +' + +``` + +在上面的示例中，你或许对下列的结构感到惊奇： +``` +t start +:start + +``` + +乍一看，在这里的分支并没有用，因为它只是跳转到将要运行的指令处。但是，如果你仔细阅读了 `test` 命令的定义，你将会看到，如果在当前循环的开始或者前一个 test 命令运行后发生了一个替换，分支才会起作用。换句话说就是，test 指令有清除替换标志的副作用。这也正是上面的代码片段的真实目的。这是一个在包含条件分支的 Sed 程序中经常看到的技巧，用于在使用多个替换命令时避免出现 false 的情况。 + +通过它并不能绝对强制地清除替换标志，我同意这一说法。因为我使用的特定的替换命令在将字符串填充到正确的长度时是幂等的。因此，一个多余的迭代并不会改变结果。不过，我们可以现在再次看一下第二个示例： +``` +# 基于它们的登录程序来分类用户帐户 +cat inputfile | sed -Ene ' + s/^/login=/ + /nologin/s/^/type=SERV / + /false/s/^/type=SERV / + t print + s/^/type=USER / + :print + s/:.*//p +' + +``` + +我希望在这里根据用户默认配置的登录程序，为用户帐户打上 “SERV” 或 “USER” 的标签。如果你运行它，预计你将看到 “SERV” 标签。然而，并没有在输出中跟踪到 “USER” 标签。为什么呢？因为 `t print` 指令不论行的内容是什么，它总是切换，替换标志总是由程序的第一个替换命令来设置。一旦替换标志设置完成后，在下一个行被读取或直到下一个 test 命令之前，这个标志将保持不变。下面我们给出修复这个程序的解决方案： +``` +# 基于用户登录程序来分类用户帐户 +cat inputfile | sed -Ene ' + s/^/login=/ + + t classify # clear the "substitution flag" + :classify + + /nologin/s/^/type=SERV / + /false/s/^/type=SERV / + t print + s/^/type=USER / + :print + s/:.*//p +' + +``` + +### 精确地处理文本 + +Sed 是一个非交互式文本编辑器。虽然是非交互式的，但仍然是文本编辑器。而如果没有在输出中插入一些东西的功能，那它就不算一个完整的文本编辑器。我不是很喜欢它的文本编辑的特性，因为我发现它的语法太难用了（即便是使用标准的 Sed），但有时你难免会用到它。 + +在严格的 POSIX 语法中，所有通过这三个命令：change（`c`）、insert（`i`）或 append（`a`）来处理一些到输出的文字文本，都遵循相同的特定语法：命令字母后面跟着一个反斜杠，并且文本从脚本的下一行上开始插入： +``` +head -5 inputfile | sed ' +1i\ +# List of user accounts +$a\ +# end +' + +``` + +插入多行文本，你必须每一行结束的位置使用一个反斜杠： +``` +head -5 inputfile | sed ' +1i\ +# List of user accounts\ +# (users 1 through 5) +$a\ +# end +' + +``` + +一些 Sed 实现，比如 GNU Sed，在初始的反斜杠后面有一个可选的换行符，即便是在 `--posix` 模式下仍然如此。我在标准中并没有找到任何关于替代该语法的授权（如果是因为我没有在标准中找到那个特性，请在评论区留言告诉我！）。因此，如果对可移植性要求很高，请注意使用它的风险： +``` +# 非 POSIX 语法： +head -5 inputfile | sed -e ' +1i \# List of user accounts +$a\# end +' + +``` + +也有一些 Sed 的实现，让初始的反斜杠完全是可选的。因此毫无疑问，它是一个厂商对 POSIX 标准进行扩展的特定版本，它是否支持那个语法，你需要去查看那个 Sed 版本的手册。 + +在简单概述之后，我们现在来回顾一下这些命令的更多细节，从我还没有介绍的 change 命令开始。 + +#### change 命令 + +change 命令（`c\`）就像 `d` 命令一样删除 `pattern` 空间的内容并开始一个新的循环。唯一的不同在于，当命令运行之后，用户提供的文本是写往输出的。 + +![The Sed `change` command][34] +``` +cat -n inputfile | sed -e ' +/systemd/c\ +# :REMOVED: +s/:.*// # This will NOT be applied to the "changed" text +' + +``` + +如果 change 命令与一个地址范围关联，当到达范围的最后一行时，这个文本将仅输出一次。这在某种程度上成为 Sed 命令将被重复应用在地址范围内所有行这一惯例的一个例外情况： +``` +cat -n inputfile | sed -e ' +19,22c\ +# :REMOVED: +s/:.*// # This will NOT be applied to the "changed" text +' + +``` + +因此，如果你希望将 change 命令重复应用到地址范围内的所有行上，除了将它封装到一个块中之外，你将没有其它的选择： +``` +cat -n inputfile | sed -e ' +19,22{c\ +# :REMOVED: +} +s/:.*// # This will NOT be applied to the "changed" text +' + +``` + +#### insert 命令 + +insert 命令（`i\`）将立即在输出中给出用户提供的文本。它并不以任何方式修改程序流或缓冲区的内容。 + +![The Sed `insert` command][35] +``` +# display the first five user names with a title on the first row +sed < inputfile -e ' +1i\ +USER NAME +s/:.*// +5q +' + +``` + +#### append 命令 + +当输入的下一行被读取时，append 命令（`a\`）将一些文本追加到显示队列。文本在当前循环的结束部分（包含程序结束的情况）或当使用 `n` 或 `N` 命令从输入中读取一个新行时被输出。 + +![The Sed `append` command][36] + +与上面相同的一个示例，但这次是插入到底部而是顶部： +``` +sed < inputfile -e ' +5a\ +USER NAME +s/:.*// +5q +' + +``` + +#### read 命令 + +这是插入一些文本内容到输出流的第四个命令：read 命令（`r`）。它的工作方式与 append 命令完全一样，但不同的，它不从 Sed 脚本中取得硬编码到脚本中的文本，而是在一个输出上写一个文件的内容。 + +read 命令只调度要读取的文件。当刷新 append 队列时，后者被高效地读取，而不是在 read 命令运行时。如果这时候对这个文件有并发的访问，或那个文件不是一个普通的文件（比如，它是一个字符设备或命名管道），或文件在读取期间被修改，这时可能会产生严重的后果。 + +作为一个例证，如果你使用我们将在下一次详细讲的 write 命令，它与 read 命令共同去写入并从一个临时文件中重新读取，你可能会获得一些创造性的结果（使用法语版的 [Shiritori][37] 游戏作为一个例证）： +``` +printf "%s\n" "Trois p'tits chats" "Chapeau d' paille" "Paillasson" | +sed -ne ' + r temp + a\ + ---- + w temp +' + +``` + +现在，在流输出中专门用于插入一些文本的 Sed 命令的清单结束了。我的最后一个示例纯属好玩，但是由于我前面提到过有一个 write 命令，这个示例将我们完美地带到下一节，在下一节我们将看到在 Sed 中如何将数据写入到一个外部文件。 + +### 输出的替代 + +Sed 的设计思想是，所有的文本转换都将写入到进程的标准输出上。但是，Sed 也有一些特性支持将数据发送到替代的目的地。你有两种方式去实现上述的输出目标替换：使用专门的 `write` 命令，或者在一个 `substitution` 命令上添加一个写入标志。 + +#### write 命令 + +write 命令（`w`）追加 `pattern` 空间的内容到给定的目标文件中。POSIX 要求在 Sed 处理任何数据之前，目标文件能够被 Sed 所创建。如果给定的目标文件已经存在，它将被覆写。 + +![The Sed `write` command][38] + +因此，即便是你从未真实地去写入到一个文件中，但文件仍然会被创建。例如，下列的 Sed 程序将创建/覆写这个 “output” 文件，那怕是这个写入命令从未被运行过： +``` +echo | sed -ne ' +q # 立刻退出 +w output # 这个命令从未被运行 +' + +``` + +你可以将几个写入命令指向到同一个目标文件。指向同一个目标文件的所有写入命令将追加那个文件的内容（工作方式几乎与 shell 的重定向符 `>>` 相同）: +``` +sed < inputfile -ne ' +/:\/bin\/false$/w server +/:\/usr\/sbin\/nologin$/w server +w output +' +cat server + +``` + +#### 替换命令的写入标志 + +在前面，我们已经学习了替换命令，它有一个 `p` 选项用于在替换之后输出 `pattern` 空间的内容。同样它也提供一个类似功能的 `w` 选项，用于在替换之后将 `pattern` 空间的内容输出到一个文件中： +``` +sed < inputfile -ne ' +s/:.*\/nologin$//w server +s/:.*\/false$//w server +' +cat server + +``` + +我无数次使用过它们，但我从未花时间正式介绍过它们，因此，我决定现在来正式地介绍它们：就像大多数编程语言一样，注释是添加软件不去解析的自由格式文本的一种方法。Sed 的语法很晦涩，我不得不强调在脚本中需要的地方添加足够的注释。否则，除了作者外其他人将几乎无法理解它。 + +![The Sed `comment` command][39] + +不过，和 Sed 的其它部分一样，注释也有它自己的微妙之处。首先并且是最重要的，注释并不是语法结构，但它在 Sed 中很成熟。注释虽然是一个“什么也不做”的命令，但它仍然是一个命令。至少，它是在 POSIX 中定义了的。因此，严格地说，它们只允许使用在其它命令允许使用的地方。 + +大多数 Sed 实现都通过允许行内命令来放松了那种要求，就像在那个文章中我到处都使用的那样。 + +结束那个主题之前，需要说一下 `#n` 注释（`#` 后面紧跟一个`n`，中间没有空格）的特殊情况。如果在脚本的第一行找到这个精确注释，Sed 将切换到静默模式（即：清除自动输出标志），就像在命令行上指定了 `-n` 选项一样。 + +### 很少用得到的命令 + +现在，我们已经学习的命令能让你写出你所用到的 99.99% 的脚本。但是，如果我没有提到剩余的 Sed 命令，那么本教程就不能称为完全指南。我把它们留到最后是因为我们很少用到它。但或许你有实际使用案例，那么你就会发现它们很有用。如果是那样，请不要犹豫，在下面的评论区中把它分享给我们吧。 + +#### 行数命令 + +这个 `=` 命令将向标准输出上显示当前 Sed 正在读取的行数，这个行数就是行计数器的内容。没有任何方式从任何一个 Sed 缓冲区中捕获那个数字，也不能对它进行输出格式化。由于这两个限制使得这个命令的可用性大大降低。 + +![The Sed `line number` command][40] + +请记住，在严格的 POSIX 兼容模式中，当在命令行上给定几个输入文件时，Sed 并不重置那个计数器，而是连续地增长它，就像所有的输入文件是连接在一起的一样。一些 Sed 实现，像 GNU Sed，它就有一个选项可以在每个输入文件读取结束后去重置计数器。 + +#### 明确的 print 命令 + +这个 `l`（小写的字母 `l`）作用类似于 print 命令（`p`），但它是以精确的格式去输出 `pattern` 空间的内容。以下引用自 [POSIX 标准][12]： + +> 在 XBD 转义序列中列出的字符和相关的动作（‘\\\’、‘\a’、‘\b’、‘\f’、‘\r’、‘\t’、‘\v’）将被写为相应的转义序列；在那个表中的 ‘\n’ 是不适用的。不在那个表中的不可打印字符将被写为一个三位八进制数字（在前面使用一个 <反斜杠>），表示字符中的每个字节（最重要的字节在前面）。长行应该被换行，通过写一个 <反斜杠>后跟一个 <换行符> 来表示换行点；发生换行时的长度是不确定的，但应该适合输出设备的具体情况。每个行应该以一个 ‘$’ 标记结束。 + +![The Sed `unambiguous print` command][3]![The Sed `unambiguous print` command][41] + +我怀疑这个命令是在非 [8位规则化信道][42] 上交换数据的。就我本人而言，除了调试用途以外，也从未使用过它。 + +#### transliterate 命令 + +移译transliterate（`y`）命令允许映射 `pattern` 空间的字符从一个源集到一个目标集。它非常类似于 `tr` 命令，但是限制更多。 + +![The Sed `transliterate` command][43] +``` +# The `y` c0mm4nd 1s for h4x0rz only +sed < inputfile -e ' + s/:.*// + y/abcegio/48<3610/ +' + +``` + +虽然 transliterate 命令语法与 substitution 命令的语法有一些相似之处，但它在替换字符串之后不接受任何选项。这个移译总是全局的。 + +请注意，移译命令要求源集和目标集之间要一一对应地转换。这意味着下面的 Sed 程序可能所做的事情并不是你乍一看所想的那样： + +``` +# BEWARE: this doesn't do what you may think! +sed < inputfile -e ' + s/:.*// + y/[a-z]/[A-Z]/ +' + +``` + +### 写在最后的话 +``` +# 它要做什么？ +# 提示：答案就在不远处... +sed -E ' + s/.*\W(.*)/\1/ + h + ${ x; p; } + d' < inputfile + +``` + +我们已经学习了所有的 Sed 命令，真不敢相信我们已经做到了！如果你也读到这里了，应该恭喜你，尤其是如果你花费了一些时间，在你的系统上尝试了所有的不同示例！ + +正如你所见，Sed 是非常复杂的，不仅因为它的语法比较零乱，也因为许多极端案例或命令行为之间的细微差别。毫无疑问，我们可以将这些归结于历史的原因。尽管它有这么多缺点，但是 Sed 仍然是一个非常强大的工具，甚至到现在，它仍然是大量使用的、为数不多的 Unix 工具箱中的命令之一。是时候总结一下这篇文章了，如果你不先支持我，我将不去总结它：请节选你对喜欢的或最具创意的 Sed 脚本，并共享给我们。如果我收集到的你们共享出的脚本足够多了，我将会把这些 Sed 脚本结集发布！ + +-------------------------------------------------------------------------------- + +via: https://linuxhandbook.com/sed-reference-guide/ + +作者：[Sylvain Leroux][a] +选题：[lujun9972](https://github.com/lujun9972) +译者：[qhwdw](https://github.com/qhwdw) +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://linuxhandbook.com/author/sylvain/ +[1]:https://linuxhandbook.com/sed-command-basics/ +[2]:https://gist.github.com/s-leroux/5cb36435bac46c10cfced26e4bf5588c +[3]:https://linuxhandbook.com/wp-content/plugins/jetpack/modules/lazy-images/images/1x1.trans.gif +[4]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05/sed-reference-guide.jpeg?resize=702%2C395&ssl=1 +[5]:http://mathworld.wolfram.com/AbstractMachine.html +[6]:https://en.wikipedia.org/wiki/State_(computer_science) +[7]:https://en.wikipedia.org/wiki/Data_buffer +[8]:https://en.wikipedia.org/wiki/Processor_register#Categories_of_registers +[9]:https://www.computerhope.com/jargon/f/flag.htm +[10]:https://i1.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-flowchart.png?w=702&ssl=1 +[11]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-print-command.png?w=702&ssl=1 +[12]:http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sed.html +[13]:https://www.regular-expressions.info/ +[14]:https://chortle.ccsu.edu/FiniteAutomata/Section07/sect07_16.html +[15]:https://www.regular-expressions.info/posix.html#bre +[16]:https://www.regular-expressions.info/posix.html#ere +[17]:https://www.regular-expressions.info/repeat.html#limit +[18]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-quit-command.png?w=702&ssl=1 +[19]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-substitution-command.png?w=702&ssl=1 +[20]:https://linuxhandbook.com/?p=128 +[21]:https://www.regular-expressions.info/repeat.html#greedy +[22]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-delete-command.png?w=702&ssl=1 +[23]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-next-command.png?w=702&ssl=1 +[24]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-exchange-command.png?w=702&ssl=1 +[25]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-hold-command.png?w=702&ssl=1 +[26]:https://i1.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-get-command.png?w=702&ssl=1 +[27]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-delete-upper-command.png?w=702&ssl=1 +[28]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-next-upper-command.png?w=702&ssl=1 +[29]:https://en.wikipedia.org/wiki/FIFO_(computing_and_electronics) +[30]:https://chortle.ccsu.edu/StructuredC/Chap01/struct01_5.html +[31]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-branch-command.png?w=702&ssl=1 +[32]:https://i1.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-label-command.png?w=702&ssl=1 +[33]:https://i1.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-test-command.png?w=702&ssl=1 +[34]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-change-command.png?w=702&ssl=1 +[35]:https://i0.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-insert-command.png?w=702&ssl=1 +[36]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-append-command.png?w=702&ssl=1 +[37]:https://en.wikipedia.org/wiki/Shiritori +[38]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-write-command.png?w=702&ssl=1 +[39]:https://i1.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-comment-command.png?w=702&ssl=1 +[40]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-current-line-command.png?w=702&ssl=1 +[41]:https://i2.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-unambiguous-print-command.png?w=702&ssl=1 +[42]:https://en.wikipedia.org/wiki/8-bit_clean +[43]:https://i1.wp.com/linuxhandbook.com/wp-content/uploads/2018/05//sed-transliterate-command.png?w=702&ssl=1 diff --git a/translated/tech/20180912 How to build rpm packages.md b/translated/tech/20180912 How to build rpm packages.md new file mode 100644 index 0000000000..8506184294 --- /dev/null +++ b/translated/tech/20180912 How to build rpm packages.md @@ -0,0 +1,390 @@ +如何构建rpm包 +====== + +节省跨多个主机安装文件和脚本的时间和精力。 + +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/OSDC_gift_giveaway_box_520x292.png?itok=w1YQhNH1) + +自20多年前我开始使用 Linux 以来，我已经使用过基于 rpm 的软件包管理器在 Red Hat 和 Fedora Linux系统上安装软件。我使用过 **rpm** 程序本身，还有 **yum** 和 **DNF** ，用于在我的 Linux 主机上安装和更新软件包，DNF 是 yum 的一个紧密后代。 yum 和 DNF 工具是 rpm 实用程序的包装器，它提供了其他功能，例如查找和安装包依赖项的功能。 + +多年来，我创建了许多 Bash 脚本，其中一些脚本具有单独的配置文件，我希望在大多数新计算机和虚拟机上安装这些脚本。这也能解决安装所有这些软件包需要花费大量时间的难题，因此我决定通过创建一个 rpm 软件包来自动执行该过程，我可以将其复制到目标主机并将所有这些文件安装在适当的位置。虽然 **rpm** 工具以前用于构建 rpm 包，但该功能已被删除，并且创建了一个新工具来构建新的 rpm。 + +当我开始这个项目时，我发现很少有关于创建 rpm 包的信息，但我找到了一本书，名为《Maximum RPM》，这本书才帮我弄明白了。这本书现在已经过时了，我发现的绝大多数信息都是如此。它也已经绝版，使用复印件需要花费数百美元。[Maximum RPM][1] 的在线版本是免费提供的，并保持最新。 [RPM 网站][2]还有其他网站的链接，这些网站上有很多关于 rpm 的文档。其他的信息往往是简短的，显然都是假设你已经对该过程有了很多了解。 + +此外，我发现的每个文档都假定代码需要在开发环境中从源代码编译。我不是开发人员。我是一个系统管理员，我们系统管理员有不同的需求，因为我们不需要或者我们不应该为了管理任务而去编译代码;我们应该使用 shell 脚本。所以我们没有源代码，因为它需要被编译成二进制可执行文件。我们拥有的是一个也是可执行的源代码。 + +在大多数情况下，此项目应作为非 root 用户执行。 Rpm 包永远不应该由 root 用户构建，而只能由非特权普通用户构建。我将指出哪些部分应该以 root 身份执行，哪些部分应由非 root，非特权用户执行。 + +### 准备 + +首先，打开一个终端会话，然后 `su` 到 root 用户。 请务必使用 `-` 选项以确保启用完整的 root 环境。 我不认为系统管理员应该使用 `sudo` 来执行任何管理任务。 在我的个人博客文章中可以找出为什么：[真正的系统管理员不要使用 sudo][3]。 + +``` +[student@testvm1 ~]$ su - +Password: +[root@testvm1 ~]# +``` + +创建可用于此项目的普通用户 student，并为该用户设置密码。 + +``` +[root@testvm1 ~]# useradd -c "Student User" student +[root@testvm1 ~]# passwd student +Changing password for user student. +New password: +Retype new password: +passwd: all authentication tokens updated successfully. +[root@testvm1 ~]# +``` + +构建 rpm 包需要 `rpm-build` 包，该包可能尚未安装。 现在以 root 身份安装它。 请注意，此命令还将安装多个依赖项。 数量可能会有所不同，具体取决于主机上已安装的软件包； 它在我的测试虚拟机上总共安装了17个软件包，这是非常小的。 + +``` +dnf install -y rpm-build +``` + +除非另有明确指示，否则本项目的剩余部分应以普通用户用户 student 来执行。 打开另一个终端会话并使用 `su` 切换到该用户以执行其余步骤。 使用以下命令从 GitHub 下载我准备好的开发目录结构 utils.tar 这个tar 包tarball（LCTT 译注：tarball 是以 tar 命令来打包和压缩的文件的统称）： + +``` +wget https://github.com/opensourceway/how-to-rpm/raw/master/utils.tar +``` + +此 tar 包包含将由最终 rpm 程序安装的所有文件和 Bash 脚本。 还有一个完整的 spec 文件，你可以使用它来构建 rpm。 我们将详细介绍 spec 文件的每个部分。 + +作为普通学生 student，使用你的家目录作为当前工作目录（pwd），解压缩 tar 包。 + +``` +[student@testvm1 ~]$ cd ; tar -xvf utils.tar +``` + +使用 `tree` 命令验证~/development 的目录结构和包含的文件，如下所示： + +``` +[student@testvm1 ~]$ tree development/ +development/ +├── license +│   ├── Copyright.and.GPL.Notice.txt +│   └── GPL_LICENSE.txt +├── scripts +│   ├── create_motd +│   ├── die +│   ├── mymotd +│   └── sysdata +└── spec +    └── utils.spec + +3 directories, 7 files +[student@testvm1 ~]$ +``` + +`mymotd` 脚本创建一个发送到标准输出的“当日消息”数据流。 `create_motd` 脚本运行 `mymotd` 脚本并将输出重定向到 /etc/motd 文件。 此文件用于向使用SSH远程登录的用户显示每日消息。 + +`die` 脚本是我自己的脚本，它将 `kill` 命令包装在一些代码中，这些代码可以找到与指定字符串匹配的运行程序并将其终止。 它使用 `kill -9` 来确保kill命令一定会执行。 + +`sysdata` 脚本可以显示有关计算机硬件，还有已安装的 Linux 版本，所有已安装的软件包以及硬盘驱动器元数据的数万行数据。 我用它来记录某个时间点的主机状态。 我以后可以用它作为参考。 我曾经这样做是为了维护我为客户安装的主机记录。 + +你可能需要将这些文件和目录的所有权更改为 student:student 。 如有必要，使用以下命令执行此操作： + +``` +chown -R student:student development +``` + +此文件树中的大多数文件和目录将通过你在此项目期间创建的 rpm 包安装在 Fedora 系统上。 + +### 创建构建目录结构 + +`rpmbuild` 命令需要非常特定的目录结构。 你必须自己创建此目录结构，因为没有提供自动方式。 在家目录中创建以下目录结构： + +``` +~ ─ rpmbuild +    ├── RPMS +    │   └── noarch +    ├── SOURCES +    ├── SPECS +    └── SRPMS +``` + +我们不会创建 rpmbuild/RPMS/X86_64 目录，因为对于64位编译的二进制文件这是特定于体系结构的。 我们有 shell 脚本，不是特定于体系结构的。 实际上，我们也不会使用 SRPMS 目录，它将包含编译器的源文件。 + +### 检查 spec 文件 + +每个 spec 文件都有许多部分，其中一些部分可能会被忽视或省略，取决于 rpm 构建的具体情况。 这个特定的 spec 文件不是工作所需的最小文件的示例，但它是一个很好的包含不需要编译的文件的中等复杂 spec 文件的例子。 如果需要编译，它将在`构建`部分中执行，该部分在此 spec 文件中省略掉了，因为它不是必需的。 + +#### 前言 + +这是 spec 文件中唯一没有标签的部分。 它包含运行命令 `rpm -qi [Package Name]` 时看到的大部分信息。 每个数据都是一行，由标签和标签值的文本数据组成。 + +``` +############################################################################### +# Spec file for utils +################################################################################ +# Configured to be built by user student or other non-root user +################################################################################ +# +Summary: Utility scripts for testing RPM creation +Name: utils +Version: 1.0.0 +Release: 1 +License: GPL +URL: http://www.both.org +Group: System +Packager: David Both +Requires: bash +Requires: screen +Requires: mc +Requires: dmidecode +BuildRoot: ~/rpmbuild/ + +# Build with the following syntax: +# rpmbuild --target noarch -bb utils.spec +``` + +`rpmbuild` 程序会忽略注释行。我总是喜欢在本节中添加注释，其中包含创建包所需的 `rpmbuild` 命令的确切语法。摘要标签是包的简短描述。 Name，Version 和 Release 标签用于创建 rpm 文件的名称，如utils-1.00-1.rpm 中所示。通过增加发行版号码和版本号，你可以创建 rpm 包去更新旧版本的。 + +许可证标签定义了发布包的许可证。我总是使用 GPL 的一个变体。指定许可证对于澄清包中包含的软件是开源的这一事实非常重要。这也是我将许可证和 GPL 语句包含在将要安装的文件中的原因。 + +URL 通常是项目或项目所有者的网页。在这种情况下，它是我的个人网页。 + +Group 标签很有趣，通常用于 GUI 应用程序。 Group 标签的值决定了应用程序菜单中的哪一组图标将包含此包中可执行文件的图标。与 Icon 标签（我们此处未使用）一起使用时，Group 标签允许添加图标和所需信息用于将程序启动到应用程序菜单结构中。 + +Packager 标签用于指定负责维护和创建包的人员或组织。 + +Requires 语句定义此 rpm 包的依赖项。每个都是包名。如果其中一个指定的软件包不存在，DNF 安装实用程序将尝试在 /etc/yum.repos.d 中定义的某个已定义的存储库中找到它，如果存在则安装它。如果 DNF 找不到一个或多个所需的包，它将抛出一个错误，指出哪些包丢失并终止。 + +BuildRoot 行指定顶级目录，`rpmbuild` 工具将在其中找到 spec 文件，并在构建包时在其中创建临时目录。完成的包将存储在我们之前指定的noarch子目录中。注释显示了构建此程序包的命令语法，包括定义了目标体系结构的 `–target noarch` 选项。因为这些是Bash脚本，所以它们与特定的CPU架构无关。如果省略此选项，则构建将选用正在执行构建的CPU的体系结构。 + +`rpmbuild` 程序可以针对许多不同的体系结构，并且使用 `--target` 选项允许我们在不同的体系结构主机上构建特定体系结构的包，其具有与执行构建的体系结构不同的体系结构。所以我可以在 x86_64 主机上构建一个用于 i686 架构的软件包，反之亦然。 + +如果你有自己的网站，请将打包者的名称更改为你自己的网站。 + +#### 描述 + +spec 文件的 `描述` 部分包含 rpm 包的描述。 它可以很短，也可以包含许多信息。 我们的 `描述` 部分相当简洁。 + +``` +%description +A collection of utility scripts for testing RPM creation. +``` + +#### 准备 + +`准备` 部分是在构建过程中执行的第一个脚本。 在安装程序包期间不会执行此脚本。 + +这个脚本只是一个 Bash shell 脚本。 它准备构建目录，根据需要创建用于构建的目录，并将相应的文件复制到各自的目录中。 这将包括完整编译作为构建的一部分所需的源。 + +$RPM_BUILD_ROOT 目录表示已安装系统的根目录。 在 $RPM_BUILD_ROOT 目录中创建的目录是实时文件系统中的绝对路径，例如 /user/local/share/utils，/usr/local/bin 等。 + +对于我们的包，我们没有预编译源，因为我们的所有程序都是 Bash 脚本。 因此，我们只需将这些脚本和其他文件复制到已安装系统的目录中。 + +``` +%prep +################################################################################ +# Create the build tree and copy the files from the development directories    # +# into the build tree.                                                         # +################################################################################ +echo "BUILDROOT = $RPM_BUILD_ROOT" +mkdir -p $RPM_BUILD_ROOT/usr/local/bin/ +mkdir -p $RPM_BUILD_ROOT/usr/local/share/utils + +cp /home/student/development/utils/scripts/* $RPM_BUILD_ROOT/usr/local/bin +cp /home/student/development/utils/license/* $RPM_BUILD_ROOT/usr/local/share/utils +cp /home/student/development/utils/spec/* $RPM_BUILD_ROOT/usr/local/share/utils + +exit +``` + +请注意，本节末尾的 exit 语句是必需的。 + +#### 文件 + +spec 文件的这一部分定义了要安装的文件及其在目录树中的位置。 它还指定了要安装的每个文件的文件属性以及所有者和组所有者。 文件权限和所有权是可选的，但我建议明确设置它们以消除这些属性在安装时不正确或不明确的任何可能性。 如果目录尚不存在，则会在安装期间根据需要创建目录。 + +``` +%files +%attr(0744, root, root) /usr/local/bin/* +%attr(0644, root, root) /usr/local/share/utils/* +``` + +#### 安装前 + +在我们的实验室项目的 spec 文件中，此部分为空。 这将放置那些需要 rpm 安装前执行的脚本。 + +#### 安装后 + +spec 文件的这一部分是另一个 Bash 脚本。 这个在安装文件后运行。 此部分几乎可以是你需要或想要的任何内容，包括创建文件，运行系统命令以及重新启动服务以在进行配置更改后重新初始化它们。 我们的 rpm 包的 `安装后` 脚本执行其中一些任务。 + +``` +%post +################################################################################ +# Set up MOTD scripts                                                          # +################################################################################ +cd /etc +# Save the old MOTD if it exists +if [ -e motd ] +then +   cp motd motd.orig +fi +# If not there already, Add link to create_motd to cron.daily +cd /etc/cron.daily +if [ ! -e create_motd ] +then +   ln -s /usr/local/bin/create_motd +fi +# create the MOTD for the first time +/usr/local/bin/mymotd > /etc/motd +``` + +此脚本中包含的注释应明确其用途。 + +#### 卸载后 + +此部分包含将在卸载 rpm 软件包后运行的脚本。 使用 rpm 或 DNF 删除包会删除文件部分中列出的所有文件，但它不会删除安装后部分创建的文件或链接，因此我们需要在本节中处理。 + +此脚本通常由清理任务组成，只是清除以前由rpm安装的文件，但rpm本身无法完成清除。 对于我们的包，它包括删除 `安装后` 脚本创建的链接并恢复 motd 文件的已保存原件。 + +``` +%postun +# remove installed files and links +rm /etc/cron.daily/create_motd + +# Restore the original MOTD if it was backed up +if [ -e /etc/motd.orig ] +then +   mv -f /etc/motd.orig /etc/motd +fi +``` + +#### 清理 + +这个 Bash 脚本在 rpm 构建过程之后开始清理。 下面 `清理` 部分中的两行删除了 `rpm-build` 命令创建的构建目录。 在许多情况下，可能还需要额外的清理。 + +``` +%clean +rm -rf $RPM_BUILD_ROOT/usr/local/bin +rm -rf $RPM_BUILD_ROOT/usr/local/share/utils +``` + +#### 更新日志 + +此可选的文本部分包含 rpm 及其包含的文件的更改列表。 最新的更改记录在本部分顶部。 + +``` +%changelog +* Wed Aug 29 2018 Your Name +  - The original package includes several useful scripts. it is +    primarily intended to be used to illustrate the process of +    building an RPM. +``` + +使用你自己的姓名和电子邮件地址替换标题行中的数据。 + +### 构建 rpm + +spec 文件必须位于 rpmbuild 目录树的 SPECS 目录中。 我发现最简单的方法是创建一个指向该目录中实际 spec 文件的链接，以便可以在开发目录中对其进行编辑，而无需将其复制到 SPECS 目录。 将 SPECS 目录设为当前工作目录，然后创建链接。 + +``` +cd ~/rpmbuild/SPECS/ +ln -s ~/development/spec/utils.spec +``` + +运行以下命令以构建 rpm 。 如果没有错误发生，只需要花一点时间来创建 rpm 。 + +``` +rpmbuild --target noarch -bb utils.spec +``` + +检查 ~/rpmbuild/RPMS/noarch 目录以验证新的 rpm 是否存在。 + +``` +[student@testvm1 ~]$ cd rpmbuild/RPMS/noarch/ +[student@testvm1 noarch]$ ll +total 24 +-rw-rw-r--. 1 student student 24364 Aug 30 10:00 utils-1.0.0-1.noarch.rpm +[student@testvm1 noarch]$ +``` + +### 测试 rpm + +以 root 用户身份安装 rpm 以验证它是否正确安装并且文件是否安装在正确的目录中。 rpm 的确切名称将取决于你在 Preamble 部分中标签的值，但如果你使用了示例中的值，则 rpm 名称将如下面的示例命令所示： + +``` +[root@testvm1 ~]# cd /home/student/rpmbuild/RPMS/noarch/ +[root@testvm1 noarch]# ll +total 24 +-rw-rw-r--. 1 student student 24364 Aug 30 10:00 utils-1.0.0-1.noarch.rpm +[root@testvm1 noarch]# rpm -ivh utils-1.0.0-1.noarch.rpm +Preparing...                          ################################# [100%] +Updating / installing... +   1:utils-1.0.0-1                    ################################# [100%] +``` + +检查 /usr/local/bin 以确保新文件存在。 你还应验证是否已创建 /etc/cron.daily 中的 create_motd 链接。 + +使用 `rpm -q --changelog utils` 命令查看更改日志。 使用 `rpm -ql utils` 命令（在 `ql`中为小写 L ）查看程序包安装的文件。 + +``` +[root@testvm1 noarch]# rpm -q --changelog utils +* Wed Aug 29 2018 Your Name +- The original package includes several useful scripts. it is +    primarily intended to be used to illustrate the process of +    building an RPM. + +[root@testvm1 noarch]# rpm -ql utils +/usr/local/bin/create_motd +/usr/local/bin/die +/usr/local/bin/mymotd +/usr/local/bin/sysdata +/usr/local/share/utils/Copyright.and.GPL.Notice.txt +/usr/local/share/utils/GPL_LICENSE.txt +/usr/local/share/utils/utils.spec +[root@testvm1 noarch]# +``` + +删除包。 + +``` +rpm -e utils +``` + +### 试验 + +现在，你将更改 spec 文件以要求一个不存在的包。 这将模拟无法满足的依赖关系。 在现有依赖行下立即添加以下行： + +``` +Requires: badrequire +``` + +构建包并尝试安装它。 显示什么消息？ + +我们使用 `rpm` 命令来安装和删除 `utils` 包。 尝试使用 yum 或 DNF 安装软件包。 你必须与程序包位于同一目录中，或指定程序包的完整路径才能使其正常工作。 + +### 总结 + +在这里看一下创建 rpm 包的基础知识，我们没有涉及很多标签和很多部分。 下面列出的资源可以提供更多信息。 构建 rpm 包并不困难；你只需要正确的信息。 我希望这对你有所帮助——我花了几个月的时间来自己解决问题。 + +我们没有涵盖源代码构建，但如果你是开发人员，那么从这一点开始应该是一个简单的步骤。 + +创建 rpm 包是另一种成为懒惰系统管理员的好方法，可以节省时间和精力。 它提供了一种简单的方法来分发和安装那些我们作为系统管理员需要在许多主机上安装的脚本和其他文件。 + +### 资料 + +- Edward C. Baily，Maximum RPM，Sams著，于2000年，ISBN 0-672-31105-4 +- Edward C. Baily，[Maximum RPM][1]，更新在线版本 +- [RPM文档][4]：此网页列出了 rpm 的大多数可用在线文档。 它包括许多其他网站的链接和有关 rpm 的信息。 + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/9/how-build-rpm-packages + +作者：[David Both][a] +选题：[lujun9972](https://github.com/lujun9972) +译者：[Flowsnow](https://github.com/Flowsnow) +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 +[1]: http://ftp.rpm.org/max-rpm/ +[2]: http://rpm.org/index.html +[3]: http://www.both.org/?p=960 +[4]: http://rpm.org/documentation.html \ No newline at end of file diff --git a/translated/tech/20181003 Tips for listing files with ls at the Linux command line.md b/translated/tech/20181003 Tips for listing files with ls at the Linux command line.md index b0fe9643da..110dd5f446 100644 --- a/translated/tech/20181003 Tips for listing files with ls at the Linux command line.md +++ b/translated/tech/20181003 Tips for listing files with ls at the Linux command line.md @@ -1,24 +1,25 @@ 在 Linux 命令行中使用 ls 列出文件的提示 ====== -学习一些 Linux "ls" 命令最有用的变化。 + +学习一些 Linux `ls` 命令最有用的变化。 + ![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/button_push_open_keyboard_file_organize.png?itok=KlAsk1gx) -我在 Linux 中最先学到的命令之一就是 `ls`。了解系统中文件所在目录中的内容非常重要。能够查看和修改不仅仅是一些文件还要所有文件也很重要。 +我在 Linux 中最先学到的命令之一就是 `ls`。了解系统中文件所在目录中的内容非常重要。能够查看和修改不仅仅是一些文件还有所有文件也很重要。 -我的第一个 Linux 备忘录是[单页 Linux 手册][1]，它于 1999 年发布，它成为我的首选参考资料。当我开始探索 Linux 时，我把它贴在桌子上并经常参考它。它的第一页第一列的底部有使用 `ls -l` 列出文件的命令。 +我的第一个 Linux 备忘录是[单页 Linux 手册][1]，它于 1999 年发布，成了我的首选参考资料。当我开始探索 Linux 时，我把它贴在桌子上并经常参考它。它在第一页第一列的底部介绍了 `ls -l` 列出文件的命令。 -之后，我将学习这个最基本命令的其他迭代。通过 `ls` 命令，我开始了解 Linux 文件权限的复杂性以及哪些是我的文件，哪些需要 root 或者 root 权限来修改。随着时间的推移，我习惯使用命令行，虽然我仍然使用 `ls -l` 来查找目录中的文件，但我经常使用 `ls -al`，这样我就可以看到可能需要更改的隐藏文件，比如那些配置文件。 +之后，我将学习这个最基本命令的其它迭代。通过 `ls` 命令，我开始了解 Linux 文件权限的复杂性，以及哪些是我的文件，哪些需要 root 或者 sudo 权限来修改。随着时间的推移，我习惯了使用命令行，虽然我仍然使用 `ls -l` 来查找目录中的文件，但我经常使用 `ls -al`，这样我就可以看到可能需要更改的隐藏文件，比如那些配置文件。 -根据 Eric Fischer 在[Linux 文档项目][2]中关于 `ls` 命令的文章，该命令的根源可以追溯到 1961年 MIT 的相容分时系统 （CTSS -） 上的 `listf` 命令。当 CTSS 被 [Multics][3] 代替时，命令变为 `list`，并有像 `list -all` 的开关。根据[维基百科][4]，“ls” 出现在 AT&T Unix 的原始版本中。我们今天在 Linux 系统上使用的 `ls` 命令来自 [GNU Core Utilities][5]。 +根据 Eric Fischer 在 [Linux 文档项目][2]中关于 `ls` 命令的文章，该命令的起源可以追溯到 1961 年 MIT 的相容分时系统Compatible Time-Sharing System（CTSS）上的 `listf` 命令。当 CTSS 被 [Multics][3] 代替时，命令变为 `list`，并有像 `list -all` 的开关。根据[维基百科][4]，`ls` 出现在 AT&T Unix 的原始版本中。我们今天在 Linux 系统上使用的 `ls` 命令来自 [GNU Core Utilities][5]。 -大多数时候，我只使用几个迭代的命令。使用 `ls` 或 `ls -al` 查看目录内部是我通常使用该命令的方法，但是你还应该熟悉许多其他选项。 +大多数时候，我只使用几个迭代的命令。我通常用 `ls` 或 `ls -al` 查看目录内容，但是你还应该熟悉许多其它选项。 -`$ ls -l` 提供了一个简单的目录列表： +`ls -l` 提供了一个简单的目录列表： ![](https://opensource.com/sites/default/files/uploads/linux_ls_1_0.png) -使用我的 Fedora 28 系统中的手册页，我发现 `ls` 还有许多其他选项，所有这些选项都提供了有关 Linux 文件系统的有趣且有用的信息。通过在命令提示符下输入 `man ls`，我们可以开始探索其他一些选项： +在我的 Fedora 28 系统的手册页中，我发现 `ls` 还有许多其它选项，所有这些选项都提供了有关 Linux 文件系统的有趣且有用的信息。通过在命令提示符下输入 `man ls`，我们可以开始探索其它一些选项： ![](https://opensource.com/sites/default/files/uploads/linux_ls_2_0.png) @@ -38,18 +39,16 @@ ![](https://opensource.com/sites/default/files/uploads/linux_ls_6.png) -以下是我认为有用且有趣的一些其他选项： +以下是我认为有用且有趣的一些其它选项： - * 仅列出目录中的 .txt 文件：`ls * .txt` -  * 按文件大小列出：`ls -s` -  * 按时间和日期排序：`ls -d` -  * 按扩展名排序：`ls -X` -  * 按文件大小排序：`ls -S` -  * 带有文件大小的长格式：`ls -ls` +* 仅列出目录中的 .txt 文件：`ls *.txt` +* 按文件大小列出：`ls -s` +* 按时间和日期排序：`ls -t` +* 按扩展名排序：`ls -X` +* 按文件大小排序：`ls -S` +* 带有文件大小的长格式：`ls -ls` - - -要生成指定格式的目录列表并将其定向到文件供以后查看，请输入 `ls -al> mydirectorylist`。最后，我找到的一个更奇特的命令是 `ls -R`，它提供了计算机上所有目录及其内容的递归列表。 +要生成指定格式的目录列表并将其定向到文件供以后查看，请输入 `ls -al > mydirectorylist`。最后，我找到的一个更奇特的命令是 `ls -R`，它提供了计算机上所有目录及其内容的递归列表。 有关 `ls` 命令的所有迭代的完整列表，请参阅 [GNU Core Utilities][6]。 @@ -60,7 +59,7 @@ via: https://opensource.com/article/18/10/ls-command 作者：[Don Watkins][a] 选题：[lujun9972](https://github.com/lujun9972) 译者：[geekpi](https://github.com/geekpi) -校对：[校对者ID](https://github.com/校对者ID) +校对：[pityonline](https://github.com/pityonline) 本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 diff --git a/translated/tech/20181013 How to Install GRUB on Arch Linux (UEFI).md b/translated/tech/20181013 How to Install GRUB on Arch Linux (UEFI).md new file mode 100644 index 0000000000..d466a85f2e --- /dev/null +++ b/translated/tech/20181013 How to Install GRUB on Arch Linux (UEFI).md @@ -0,0 +1,72 @@ +如何在 Arch Linux（UEFI）上安装 GRUB +====== + +![](http://fasterland.net/wp-content/uploads/2018/10/Arch-Linux-Boot-Menu-750x375.jpg) + +前段时间，我写了一篇在安装 Windows 后在 Arch Linux 上**[如何重新安装 Grub][1]的教程。** + +几周前，我不得不在我的笔记本上从头开始重新安装 **Arch Linux**，同时我发现安装 **Grub** 并不像我想的那么简单。 + +出于这个原因，由于在新安装 **Arch Linux** 时**在 UEFI bios 中安装 Grub** 并不容易，所以我要写这篇教程。 + +### 定位 EFI 分区 + +在 **Arch Linux** 上安装 **Grub** 的第一件重要事情是定位 **EFI** 分区。让我们运行以下命令以找到此分区： + +``` +# fdisk -l +``` + +我们需要检查标记为 **EFI System** 的分区，我这里是 **/dev/sda2**。 + +之后，我们需要在例如 /boot/efi 上挂载这个分区： + +``` +# mkdir /boot/efi +# mount /dev/sdb2 /boot/efi +``` + +另一件重要的事情是将此分区添加到 **/etc/fstab** 中。 + +#### 安装 Grub + +现在我们可以在我们的系统中安装 Grub： + +``` +# grub-mkconfig -o /boot/grub/grub.cfg +# grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=GRUB +``` + +#### 自动将 Windows 添加到 Grub 菜单中 + +为了自动将**Windows 条目添加到 Grub 菜单**，我们需要安装 **os-prober**： + +``` +# pacman -Sy os-prober +``` + +要添加它，让我们运行以下命令： + +``` +# os-prober +# grub-mkconfig -o /boot/grub/grub.cfg +# grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=GRUB +``` + +你可以在[这里][2]找到更多关于在 Arch Linux 上 Grub 的信息。 + +-------------------------------------------------------------------------------- + +via: http://fasterland.net/how-to-install-grub-on-arch-linux-uefi.html + +作者：[Francesco Mondello][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]: http://fasterland.net/ +[b]: https://github.com/lujun9972 +[1]: http://fasterland.net/reinstall-grub-arch-linux.html +[2]: https://wiki.archlinux.org/index.php/GRUB diff --git a/translated/tech/20181015 How To Browse And Read Entire Arch Wiki As Linux Man Pages.md b/translated/tech/20181015 How To Browse And Read Entire Arch Wiki As Linux Man Pages.md new file mode 100644 index 0000000000..5237307c94 --- /dev/null +++ b/translated/tech/20181015 How To Browse And Read Entire Arch Wiki As Linux Man Pages.md @@ -0,0 +1,151 @@ +在 Linux 手册页中查看整个 Arch Linux Wiki +====== +![](https://www.ostechnix.com/wp-content/uploads/2018/10/arch-wiki-720x340.jpg) + +不久之前，我写了篇关于一个名叫 [**arch-wiki-cli**][1] 的命令行脚本的文章，使用它可以在终端命令行中查看整个 Arch Linux Wiki。使用这个脚本，你可以很轻松的用你喜欢的文本浏览器查看整个 Arch Wiki。显然，使用这个脚本需要你有一个好的网络环境。我今天偶然发现了一个名为 **Arch-wiki-man** 的程序，与其有着相同的功能。就跟名字说的一样，它可以让你在命令行查看 Arch Wiki，但是无需联网。它可以以手册页的形式为你显示来自 Arch Wiki 的任何文章。它会下载整个 Arch Wiki，并每两天自动推送一次。因此，你的系统上总能有一份 Arch Wiki 最新的复印件。 + +### 安装 Arch-wiki-man + +Arch-wiki-man 在 [**AUR**][2] 中可用，所以你可以通过类似[**Yay**][3] 的 AUR 帮助程序安装它。 + +``` + $ yay -S arch-wiki-man +``` + +另外，它也可以使用 NPM 安装。首先确保你已经[**安装了 NoodJS**][4]，然后使用以下命令安装它。 + +``` + $ npm install -g arch-wiki-man +``` + +### 以手册页的形式查看整个 Arch Wiki + +Arch-wiki-man 的典型语法如下： + +``` + $ awman +``` + +下面看一些具体的例子： + +**搜索一个或多个匹配项** + +只需要下面的命令，就可以搜索 [**Arch Linux 安装指南**][5]。 + +``` + $ awman Installation guide +``` + +上面的命令将会从 Arch Wiki 中搜索所有包含 “安装指南” 的条目。如果对于给出的搜索条目有很多的匹配项，将会展示为一个选择菜单。使用 **上下键** 或是 Vim 风格的方向键（**j/k**），移动到你想查看的指南上，点击回车打开。然后就会像下面这样，以手册页的形式展示指南的内容。 + +![][6] + +awman 指的是 arch wiki man 的首字母组合。 + +它支持手册页的所有操作，所以你可以像使用手册页一样使用它。按 **h** 查看帮助选项。 + +![][7] + +退出选择菜单不需要输入**man**，只需要按 **Ctrl+c**。 + +输入 **q** 返回或者/并且退出手册页。 + +**在标题或者概述中搜索匹配项** + +Awman 默认只会在标题中搜索匹配项。但是你也可以指定它同时在标题和概述中搜索匹配项。 + +``` + $ awman -d vim +``` + +或者, + +``` + $ awman --desc-search vim +``` + +**在目录中搜索匹配项** + +不同于在标题和概述中搜索匹配项，它也能够扫描整个目录达到匹配的目的。不过请注意，这样将会使搜索进程明显变慢。 + +``` + $ awman -k emacs +``` + +或者, + +``` + $ awman --apropos emacs +``` + +**在 web 浏览器中打开搜索结果** + +如果你不想以手册页的形式查看 Arch Wiki 指南，你也可以像下面这样在 web 浏览器中打开它。 + +``` + $ awman -w pacman +``` + +或者, + +``` + $ awman --web pacman +``` + +这条命令将会在 web 浏览器中打开匹配结果。请注意，使用这个选项需要网络连接。 + +**在其他语言中搜索** + +Awman 默认打开的是英文的 Arch Wiki 页面。如果你想用其他的语言查看搜索结果，例如 **西班牙语**，只需要像这样做： + +``` + $ awman -l spanish codecs +``` + +![][8] + +使用以下命令查看可用的语言： + +``` + + $ awman --list-languages + +``` + +**升级本地的 Arch Wiki复印件** + +就像我已经说过的，更新会每两天自动推送一次。或者你也可以使用以下命令手动更新。 + +``` +$ awman-update +arch-wiki-man@1.3.0 /usr/lib/node_modules/arch-wiki-man +└── arch-wiki-md-repo@0.10.84 + +arch-wiki-md-repo has been successfully updated or reinstalled. +``` + +：） + + + +-------------------------------------------------------------------------------- + +via: https://www.ostechnix.com/how-to-browse-and-read-entire-arch-wiki-as-linux-man-pages/ + +作者：[SK][a] +选题：[lujun9972][b] +译者：[dianbanjiu](https://github.com/dianbanjiu) +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/search-arch-wiki-website-commandline/ +[2]: https://aur.archlinux.org/packages/arch-wiki-man/ +[3]: https://www.ostechnix.com/yay-found-yet-another-reliable-aur-helper/ +[4]: https://www.ostechnix.com/install-node-js-linux/ +[5]: https://www.ostechnix.com/install-arch-linux-latest-version/ +[6]: http://www.ostechnix.com/wp-content/uploads/2018/10/awman-1.gif +[7]: http://www.ostechnix.com/wp-content/uploads/2018/10/awman-2.png +[8]: https://www.ostechnix.com/wp-content/uploads/2018/10/awman-3-1.png