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[translating by kokialoves]
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Part 12 - LFCS: How to Explore Linux with Installed Help Documentations and Tools
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==================================================================================
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Because of the changes in the LFCS exam requirements effective Feb. 2, 2016, we are adding the necessary topics to the [LFCS series][1] published here. To prepare for this exam, your are highly encouraged to use the [LFCE series][2] as well.
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>LFCS: Explore Linux with Installed Documentations and Tools – Part 12
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Once you get used to working with the command line and feel comfortable doing so, you realize that a regular Linux installation includes all the documentation you need to use and configure the system.
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Another good reason to become familiar with command line help tools is that in the [LFCS][3] and [LFCE][4] exams, those are the only sources of information you can use – no internet browsing and no googling. It’s just you and the command line.
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For that reason, in this article we will give you some tips to effectively use the installed docs and tools in order to prepare to pass the **Linux Foundation Certification** exams.
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### Linux Man Pages
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A man page, short for manual page, is nothing less and nothing more than what the word suggests: a manual for a given tool. It contains the list of options (with explanation) that the command supports, and some man pages even include usage examples as well.
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To open a man page, use the **man command** followed by the name of the tool you want to learn more about. For example:
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```
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# man diff
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```
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will open the manual page for `diff`, a tool used to compare text files line by line (to exit, simply hit the q key.).
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Let’s say we want to compare two text files named `file1` and `file2` in Linux. These files contain the list of packages that are installed in two Linux boxes with the same distribution and version.
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Doing a `diff` between `file1` and `file2` will tell us if there is a difference between those lists:
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```
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# diff file1 file2
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```
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>Compare Two Text Files in Linux
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where the `<` sign indicates lines missing in `file2`. If there were lines missing in `file1`, they would be indicated by the `>` sign instead.
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On the other hand, **7d6** means line **#7** in file should be deleted in order to match `file2` (same with **24d22** and **41d38**), and 65,67d61 tells us we need to remove lines **65** through **67** in file one. If we make these corrections, both files will then be identical.
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Alternatively, you can display both files side by side using the `-y` option, according to the man page. You may find this helpful to more easily identify missing lines in files:
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```
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# diff -y file1 file2
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```
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>Compare and List Difference of Two Files
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Also, you can use `diff` to compare two binary files. If they are identical, `diff` will exit silently without output. Otherwise, it will return the following message: “**Binary files X and Y differ**”.
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### The –help Option
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The `--help` option, available in many (if not all) commands, can be considered a short manual page for that specific command. Although it does not provide a comprehensive description of the tool, it is an easy way to obtain information on the usage of a program and a list of its available options at a quick glance.
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For example,
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```
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# sed --help
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```
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shows the usage of each option available in sed (the stream editor).
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One of the classic examples of using `sed` consists of replacing characters in files. Using the `-i` option (described as “**edit files in place**”), you can edit a file without opening it. If you want to make a backup of the original contents as well, use the `-i` option followed by a SUFFIX to create a separate file with the original contents.
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For example, to replace each occurrence of the word `Lorem` with `Tecmint` (case insensitive) in `lorem.txt` and create a new file with the original contents of the file, do:
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```
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# less lorem.txt | grep -i lorem
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# sed -i.orig 's/Lorem/Tecmint/gI' lorem.txt
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# less lorem.txt | grep -i lorem
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# less lorem.txt.orig | grep -i lorem
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```
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Please note that every occurrence of `Lorem` has been replaced with `Tecmint` in `lorem.txt`, and the original contents of `lorem.txt` has been saved to `lorem.txt.orig`.
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>Replace A String in Files
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### Installed Documentation in /usr/share/doc
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This is probably my favorite pick. If you go to `/usr/share/doc` and do a directory listing, you will see lots of directories with the names of the installed tools in your Linux system.
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According to the [Filesystem Hierarchy Standard][5], these directories contain useful information that might not be in the man pages, along with templates and configuration files to make configuration easier.
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For example, let’s consider `squid-3.3.8` (version may vary from distribution to distribution) for the popular HTTP proxy and [squid cache server][6].
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Let’s `cd` into that directory:
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```
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# cd /usr/share/doc/squid-3.3.8
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```
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and do a directory listing:
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```
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# ls
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```
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>Linux Directory Listing with ls Command
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You may want to pay special attention to `QUICKSTART` and `squid.conf.documented`. These files contain an extensive documentation about Squid and a heavily commented configuration file, respectively. For other packages, the exact names may differ (as **QuickRef** or **00QUICKSTART**, for example), but the principle is the same.
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Other packages, such as the Apache web server, provide configuration file templates inside `/usr/share/doc`, that will be helpful when you have to configure a standalone server or a virtual host, to name a few cases.
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### GNU info Documentation
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You can think of info documents as man pages on steroids. As such, they not only provide help for a specific tool, but also they do so with hyperlinks (yes, hyperlinks in the command line!) that allow you to navigate from a section to another using the arrow keys and Enter to confirm.
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Perhaps the most illustrative example is:
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```
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# info coreutils
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```
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Since coreutils contains the [basic file, shell and text manipulation utilities][7] which are expected to exist on every operating system, you can reasonably expect a detailed description for each one of those categories in info **coreutils**.
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>Info Coreutils
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As it is the case with man pages, you can exit an info document by pressing the `q` key.
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Additionally, GNU info can be used to display regular man pages as well when followed by the tool name. For example:
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```
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# info tune2fs
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```
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will return the man page of **tune2fs**, the ext2/3/4 filesystems management tool.
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And now that we’re at it, let’s review some of the uses of **tune2fs**:
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Display information about the filesystem on top of **/dev/mapper/vg00-vol_backups**:
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```
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# tune2fs -l /dev/mapper/vg00-vol_backups
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```
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Set a filesystem volume name (Backups in this case):
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```
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# tune2fs -L Backups /dev/mapper/vg00-vol_backups
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```
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Change the check intervals and `/` or mount counts (use the `-c` option to set a number of mount counts and `/` or the `-i` option to set a check interval, where **d=days, w=weeks, and m=months**).
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```
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# tune2fs -c 150 /dev/mapper/vg00-vol_backups # Check every 150 mounts
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# tune2fs -i 6w /dev/mapper/vg00-vol_backups # Check every 6 weeks
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```
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All of the above options can be listed with the `--help` option, or viewed in the man page.
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### Summary
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Regardless of the method that you choose to invoke help for a given tool, knowing that they exist and how to use them will certainly come in handy in the exam. Do you know of any other tools that can be used to look up documentation? Feel free to share with the Tecmint community using the form below.
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Questions and other comments are more than welcome as well.
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--------------------------------------------------------------------------------
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via: http://www.tecmint.com/linux-basic-shell-scripting-and-linux-filesystem-troubleshooting/
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作者：[Gabriel Cánepa][a]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:http://www.tecmint.com/author/gacanepa/
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[1]: http://www.tecmint.com/sed-command-to-create-edit-and-manipulate-files-in-linux/
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[2]: http://www.tecmint.com/installing-network-services-and-configuring-services-at-system-boot/
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[3]: http://www.tecmint.com/sed-command-to-create-edit-and-manipulate-files-in-linux/
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[4]: http://www.tecmint.com/installing-network-services-and-configuring-services-at-system-boot/
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[5]: http://www.tecmint.com/linux-directory-structure-and-important-files-paths-explained/
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[6]: http://www.tecmint.com/configure-squid-server-in-linux/
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[7]: http://www.tecmint.com/sed-command-to-create-edit-and-manipulate-files-in-linux/
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[8]:
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@ -0,0 +1,178 @@
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LFCS第十二讲: 如何使用Linux的帮助文档和工具
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==================================================================================
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由于 2016 年 2 月 2 号开始启用了新的 LFCS 考试要求, 我们在[LFCS series][1]系列添加了一些必要的内容 . 为了考试的需要, 我们强烈建议你看一下[LFCE series][2] .
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>LFCS: 了解Linux的帮助文档和工具
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当你习惯了在命令行下进行工作, 你会发现Linux有许多文档需要你去使用和配置Linux系统.
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另一个你必须熟悉命令行帮助工具的理由是，在[LFCS][3] 和 [LFCE][4] 考试中, 你只能靠你自己和命令行工具，没有互联网也没有百度。
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基于上面的理由, 在这一章里我们将给你一些建议来帮助你通过**Linux Foundation Certification** 考试.
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### Linux 帮助手册
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man命令, 大体上来说就是一个工具手册. 它包含选项列表(和解释) , 甚至还提供一些例子.
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我们用**man command** 加工具名称来打开一个帮助手册以便获取更多内容. 例如:
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```
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# man diff
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```
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我们将打开`diff`的手册页, 这个工具将一行一行的对比文本文档 (如你想退出只需要轻轻的点一下Q键).
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下面我来比较两个文本文件 `file1` 和 `file2` . 这两个文本文件包含着相同版本Linux的安装包信息.
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输入`diff` 命令它将告诉我们 `file1` 和`file2` 有什么不同:
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```
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# diff file1 file2
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```
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>在Linux中比较两个文本文件
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`<` 这个符号是说`file2`少一行. 如果是 `file1`少一行, 我们将用 `>` 符号来替代.
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接下来说, **7d6** 意思是说 文件1的**#7**行在 `file2`中被删除了 ( **24d22** 和**41d38**是同样的意思), 65,67d61告诉我们移动 **65** 到 **67** . 我们把以上步骤都做了两个文件将完全匹配.
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你还可以通过 `-y` 选项来对比两个文件:
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```
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# diff -y file1 file2
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```
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>通过列表来列出两个文件的不同
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当然你也可以用`diff`来比较两个二进制文件 . 如果它们完全一样, `diff` 将什么也不会输出. 否则, 他将会返回如下信息: “**Binary files X and Y differ**”.
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### –help 选项
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`--help`选项 , 大多数命令都可以用它(并不是所有) , 他可以理解为一个命令的简单介绍. 尽管它不提供工具的详细介绍, 但是确实是一个能够快速列出程序使用信息的不错的方法.
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例如,
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```
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# sed --help
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```
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显示 sed 的每个选项的用法(sed文本流编辑器).
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一个经典的`sed`例子，替换文件字符. 用 `-i` 选项 (描述为 “**编辑文件在指定位置**”), 你可以编辑一个文件而且并不需要打开他. 如果你想要备份一个原始文件, 用 `-i` 选项 加后缀来创建一个原始文件的副本.
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例如, 替换 `lorem.txt`中的`Lorem` 为 `Tecmint` (忽略大小写) 并且创建一个新的原始文件副本, 命令如下:
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```
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# less lorem.txt | grep -i lorem
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# sed -i.orig 's/Lorem/Tecmint/gI' lorem.txt
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# less lorem.txt | grep -i lorem
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# less lorem.txt.orig | grep -i lorem
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```
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请注意`lorem.txt`文件中`Lorem` 都已经替换为 `Tecmint` , 并且原始的 `lorem.txt` 保存为`lorem.txt.orig`.
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>替换文件文本
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### /usr/share/doc内的文档
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这可能是我最喜欢的方法. 如果你进入 `/usr/share/doc` 目录, 你可以看到好多Linux已经安装的工具的名称的文件夹.
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根据[Filesystem Hierarchy Standard][5](文件目录标准),这些文件夹包含了许多帮助手册没有的信息, 还有一些模板和配置文件.
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例如, 让我们来看一下 `squid-3.3.8` (版本可能会不同) 一个非常受欢迎的HTTP代理[squid cache server][6].
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让我们用`cd`命令进入目录 :
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```
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# cd /usr/share/doc/squid-3.3.8
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```
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列出当前文件夹列表:
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```
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# ls
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```
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>ls linux列表命令
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你应该特别注意 `QUICKSTART` 和 `squid.conf.documented`. 这两个文件包含了Squid许多信息, . 对于别的安装包来说, 他们的名字可能不同 (有可能是 **QuickRef** 或者**00QUICKSTART**), 但原理是一样的.
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对于另外一些安装包, 比如 the Apache web server, 在`/usr/share/doc`目录提供了配置模板, 当你配置独立服务器或者虚拟主机的时候会非常有用.
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### GNU 信息文档
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你可以把它想象为帮助手册的超级链接形式. 正如上面说的, 他不仅仅提供工具的帮助信息, 而且还是超级链接的形式(是的!在命令行中的超级链接) 你可以通过箭头按钮和回车按钮来浏览你需要的内容.
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一个典型的例子是:
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```
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# info coreutils
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```
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通过coreutils 列出当前系统的 基本文件，shell脚本和文本处理工具[basic file, shell and text manipulation utilities][7] , 你可以得到他们的详细介绍.
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>Info Coreutils
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和帮助手册一样你可以按Q键退出.
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此外, GNU info 还可以像帮助手册一样使用. 例如:
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```
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# info tune2fs
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```
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它将显示 **tune2fs**的帮助手册, ext2/3/4 文件系统管理工具.
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让我们来看看怎么用**tune2fs**:
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显示 **/dev/mapper/vg00-vol_backups**文件系统信息:
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```
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# tune2fs -l /dev/mapper/vg00-vol_backups
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```
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修改文件系统标签 (修改为Backups):
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```
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# tune2fs -L Backups /dev/mapper/vg00-vol_backups
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```
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设置 `/` 自检的挂载次数 (用`-c` 选项设置 `/`的自检的挂载次数 或者用 `-i` 选项设置 自检时间 **d=days, w=weeks, and m=months**).
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```
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# tune2fs -c 150 /dev/mapper/vg00-vol_backups # Check every 150 mounts
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# tune2fs -i 6w /dev/mapper/vg00-vol_backups # Check every 6 weeks
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```
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以上这些内容也可以通过 `--help` 选项找到, 或者查看帮助手册.
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### 摘要
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不管你选择哪种方法，知道并且会使用它们在考试中对你是非常有用的. 你知道其它的一些方法吗? 欢迎给我们留言.
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--------------------------------------------------------------------------------
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||||
via: http://www.tecmint.com/linux-basic-shell-scripting-and-linux-filesystem-troubleshooting/
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作者：[Gabriel Cánepa][a]
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译者：[kokialoves](https://github.com/kokialoves)
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校对：[校对者ID](https://github.com/校对者ID)
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||||
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:http://www.tecmint.com/author/gacanepa/
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[1]: http://www.tecmint.com/sed-command-to-create-edit-and-manipulate-files-in-linux/
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[2]: http://www.tecmint.com/installing-network-services-and-configuring-services-at-system-boot/
|
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[3]: http://www.tecmint.com/sed-command-to-create-edit-and-manipulate-files-in-linux/
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[4]: http://www.tecmint.com/installing-network-services-and-configuring-services-at-system-boot/
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[5]: http://www.tecmint.com/linux-directory-structure-and-important-files-paths-explained/
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[6]: http://www.tecmint.com/configure-squid-server-in-linux/
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[7]: http://www.tecmint.com/sed-command-to-create-edit-and-manipulate-files-in-linux/
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[8]:
|
||||
Loading…
Reference in New Issue
Block a user