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[#]: collector: (lujun9972)
[#]: translator: (wxy)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
[#]: subject: (Master the Linux 'ls' command)
[#]: via: (https://opensource.com/article/19/7/master-ls-command)
[#]: author: (Seth Kenlon https://opensource.com/users/seth)
Master the Linux 'ls' command
======
Linux's 'ls' command has a staggering number of options that can provide
important information about your files.
![Hand putting a Linux file folder into a drawer][1]
The **ls** command lists files on a [POSIX][2] system. It's a simple command, often underestimated, not in what it can do (because it really does only one thing), but in how you can optimize your use of it.
Of the 10 most essential terminal commands to know, the humble **ls** command is in the top three, because **ls** doesn't _just_ list files, it tells you important information about them. It tells you things like who owns a file or directory, when each file was lost or modified, and even what kind of file it is. And then there's its incidental function of giving you a sense of where you are, what nearby objects are lying around, and what you can do with them.
If your experience with **ls** is limited to whatever your distribution aliases it to in **.bashrc**, then you're probably missing out.
### GNU or BSD?
Before looking at the hidden powers of **ls**, you must determine which **ls** command you're running. The two most popular versions are the GNU version, included in the GNU **coreutils** package, and the BSD version. If you're running Linux, then you probably have **ls** installed. If you're running BSD or MacOS, then you have the BSD version. There are differences, for which this article accounts.
You can find out which version is on your computer with the **\--version** option:
```
`$ ls --version`
```
If this returns information about GNU coreutils, then you have the GNU version. If it returns an error, you're probably running the BSD version (run **man ls | head** to be sure).
You should also investigate what presets your distribution may have in place. Customizations to terminal commands are frequently placed in **$HOME/.bashrc** or **$HOME/.bash_aliases** or **$HOME/.profile**, and they're accomplished by aliasing **ls** to a more complex **ls** command. For example:
```
`alias ls='ls --color'`
```
The presets provided by distributions are very helpful, but they do make it difficult to discern what **ls** does on its own and what its additional options provide. Should you ever want to run **ls** and not the alias, you can "escape" the command with a backslash:
```
`$ \ls`
```
### Classify
Run on its own, **ls** simply lists files in as many columns as can fit into your terminal:
```
$ ls ~/example
bunko        jdk-10.0.2
chapterize   otf2ttf.ff
despacer     overtar.sh
estimate.sh  pandoc-2.7.1
fop-2.3      safe_yaml
games        tt
```
It's useful information, but all of those files look basically the same without the convenience of icons to quickly convey which is a directory, or a text file, or an image, and so on.
Use the **-F** (or **\--classify** on GNU) to show indicators after each entry that identify the kind of file it is:
```
$ ls ~/example
bunko         jdk-10.0.2/
chapterize*   otf2ttf.ff*
despacer*     overtar.sh*
estimate.sh   pandoc@
fop-2.3/      pandoc-2.7.1/
games/        tt*
```
With this option, items listed in your terminal are classified by file type using this shorthand:
* A slash (**/**) denotes a directory (or "folder").
* An asterisk (*****) denotes an executable file. This includes a binary file (compiled code) as well as scripts (text files that have [executable permission][3]).
* An at sign (**@**) denotes a symbolic link (or "alias").
* An equals sign (**=**) denotes a socket.
* On BSD, a percent sign (**%**) denotes a whiteout (a method of file removal on certain file systems).
* On GNU, an angle bracket (**>**) denotes a door (inter-process communication on [Illumos][4] and Solaris).
* A vertical bar (**|**) denotes a [FIFO][5].
A simpler version of this option is **-p**, which only differentiates a file from a directory.
### Long list
Getting a "long list" from **ls** is so common that many distributions alias **ll** to **ls -l**. The long list form provides many important file attributes, such as permissions, the user who owns each file, the group to which the file belongs, the file size in bytes, and the date the file was last changed:
```
$ ls -l
-rwxrwx---. 1 seth users         455 Mar  2  2017 estimate.sh
-rwxrwxr-x. 1 seth users         662 Apr 29 22:27 factorial
-rwxrwx---. 1 seth users    20697793 Jun 29  2018 fop-2.3-bin.tar.gz
-rwxrwxr-x. 1 seth users        6210 May 22 10:22 geteltorito
-rwxrwx---. 1 seth users         177 Nov 12  2018 html4mutt.sh
[...]
```
If you don't think in bytes, add the **-h** flag (or **\--human** in GNU) to translate file sizes to more human-friendly notation:
```
$ ls --human
-rwxrwx---. 1 seth users    455 Mar  2  2017 estimate.sh
-rwxrwxr-x. 1 seth seth     662 Apr 29 22:27 factorial
-rwxrwx---. 1 seth users    20M Jun 29  2018 fop-2.3-bin.tar.gz
-rwxrwxr-x. 1 seth seth    6.1K May 22 10:22 geteltorito
-rwxrwx---. 1 seth users    177 Nov 12  2018 html4mutt.sh
```
You can see just a little less information by showing only the owner column with **-o** or only the group column with **-g**:
```
$ ls -o
-rwxrwx---. 1 seth    455 Mar  2  2017 estimate.sh
-rwxrwxr-x. 1 seth    662 Apr 29 22:27 factorial
-rwxrwx---. 1 seth    20M Jun 29  2018 fop-2.3-bin.tar.gz
-rwxrwxr-x. 1 seth   6.1K May 22 10:22 geteltorito
-rwxrwx---. 1 seth    177 Nov 12  2018 html4mutt.sh
```
Combine both options to show neither.
### Time and date format
The long list format of **ls** usually looks like this:
```
-rwxrwx---. 1 seth users         455 Mar  2  2017 estimate.sh
-rwxrwxr-x. 1 seth users         662 Apr 29 22:27 factorial
-rwxrwx---. 1 seth users    20697793 Jun 29  2018 fop-2.3-bin.tar.gz
-rwxrwxr-x. 1 seth users        6210 May 22 10:22 geteltorito
-rwxrwx---. 1 seth users         177 Nov 12  2018 html4mutt.sh
```
The names of months aren't easy to sort, both computationally or (depending on whether your brain tends to prefer strings or integers) by recognition. You can change the format of the time stamp with the **\--time-style** option plus the name of a format. Available formats are:
* full-iso (1970-01-01 21:12:00)
* long-iso (1970-01-01 21:12)
* iso (01-01 21:12)
* locale (uses your locale settings)
* posix-STYLE (replace STYLE with a locale definition)
You can also create a custom style using the formal notation of the **date** command.
### Sort by time
Usually, the **ls** command sorts alphabetically. You can make it sort according to which file was most recently changed (the newest is listed first) with the **-t** option.
For example:
```
$ touch foo bar baz
$ ls
bar  baz  foo
$ touch foo
$ ls -t
foo bar baz
```
### List type
The standard output of **ls** balances readability with space efficiency, but sometimes you want your file list in a specific arrangement.
For a comma-separated list of files, use **-m**:
```
ls -m ~/example
bar, baz, foo
```
To force one file per line, use the **-1** option (that's the number one, not a lowercase L):
```
$ ls -1 ~/bin/
bar
baz
foo
```
To sort entries by file extension rather than the filename, use **-X** (that's a capital X):
```
$ ls
bar.xfc  baz.txt  foo.asc
$ ls -X
foo.asc  baz.txt  bar.xfc
```
### Hide the clutter
There are a few entries in some **ls** listings that you may not care about. For instance, the metacharacters **.** and **..** represent "here" and "back one level," respectively. If you're familiar with navigating in a terminal, you probably already know that each directory refers to itself as **.** and to its parent as **..**, so you don't need to be constantly reminded of it when you use the **-a** option to show hidden files.
To show almost all hidden files (the **.** and **..** excluded), use the **-A** option:
```
$ ls -a
.
..
.android
.atom
.bash_aliases
[...]
$ ls -A
.android
.atom
.bash_aliases
[...]
```
With many good Unix tools, there's a tradition of saving backup files by appending some special character to the name of the file being saved. For instance, in Vim, backups get saved with the **~** character appended to the name.
These kinds of backup files have saved me from stupid mistakes on several occasions, but after years of enjoying the sense of security they provide, I don't feel the need to have visual evidence that they exist. I trust Linux applications to generate backup files (if they claim to do so), and I'm happy to take it on faith that they exist.
To hide backup files from view, use **-B** or **\--ignore-backups** to conceal common backup formats (this option is not available in BSD **ls**):
```
$ ls
bar.xfc  baz.txt  foo.asc~  foo.asc
$ ls -B
bar.xfc  baz.txt  foo.asc
```
Of course, the backup file still exists; it's just filtered out so that you don't have to look at it.
GNU Emacs saves backup files (unless otherwise configured) with a hash character (**#**) at the start and end of the file name (**#file#**). Other applications may use a different style. It doesn't matter what pattern is used, because you can create your own exclusions with the **\--hide** option:
```
$ ls
bar.xfc  baz.txt  #foo.asc#  foo.asc
$ ls --hide="#*#"
bar.xfc  baz.txt  foo.asc
```
### List directories with recursion
The contents of directories are not listed with the **ls** command unless you run **ls** on that directory specifically:
```
$ ls -F
example/  quux*  xyz.txt
$ ls -R
quux  xyz.txt
./example:
bar.xfc  baz.txt  #foo.asc#  foo.asc
```
### Make it permanent with an alias
The **ls** command is probably the command used most often during any given shell session. It's your eyes and ears, providing you with context and confirming the results of commands. While it's useful to have lots of options, part of the beauty of **ls** is its brevity: two characters and the Return key, and you know exactly where you are and what's nearby. If you have to stop to think about (much less type) several different options, it becomes less convenient, so typically even the most useful options are left off.
The solution is to alias your **ls** command so that when you use it, you get the information you care about the most.
To create an alias for a command in the Bash shell, create a file in your home directory called **.bash_aliases** (you must include the dot at the beginning). In this file, list the command you want to create an alias for and then the alias you want to create. For example:
```
`alias ls='ls -A -F -B --human --color'`
```
This line causes your Bash shell to interpret the **ls** command as **ls -A -F -B --human --color**.
You aren't limited to redefining existing commands. You can create your own aliases:
```
alias ll='ls -l'
alias la='ls -A'
alias lh='ls -h'
```
For aliases to work, your shell must know that the **.bash_aliases** configuration file exists. Open the **.bashrc** file in an editor (or create it, if it doesn't exist), and include this block of code:
```
if [ -e $HOME/.bash_aliases ]; then
    source $HOME/.bash_aliases
fi
```
Each time **.bashrc** is loaded (which is any time a new Bash shell is launched), Bash will load **.bash_aliases** into your environment. You can close and relaunch your Bash session or just force it to do that now:
```
`$ source ~/.bashrc`
```
If you forget whether you have aliased a command, the **which** command tells you:
```
$ which ls
alias ls='ls -A -F -B --human --color'
        /usr/bin/ls
```
If you've aliased the **ls** command to itself with options, you can override your own alias at any time by prefacing **ls** with a backslash. For instance, in the example alias, backup files are hidden using the **-B** option, which means there's no way to back up files with the **ls** command. Override the alias to see the backup files:
```
$ ls
bar  baz  foo
$ \ls
bar  baz  baz~  foo
```
### Do one thing and do it well
The **ls** command has a staggering number of options, many of which are niche or highly dependent upon the terminal you use. Take a look at **info ls** on GNU systems or **man ls** on GNU or BSD systems for more options.
You might find it strange that a system famous for the premise that each tool "does one thing and does it well" would weigh down its most common command with 50 options. But **ls** does only one thing: it lists files. And with 50 options to allow you to control how you receive that list, **ls** does its one job very, _very_ well.
--------------------------------------------------------------------------------
via: https://opensource.com/article/19/7/master-ls-command
作者：[Seth Kenlon][a]
选题：[lujun9972][b]
译者：[译者ID](https://github.com/译者ID)
校对：[校对者ID](https://github.com/校对者ID)
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
[a]: https://opensource.com/users/sethhttps://opensource.com/users/sambocettahttps://opensource.com/users/scottnesbitthttps://opensource.com/users/sethhttps://opensource.com/users/marcobravohttps://opensource.com/users/sethhttps://opensource.com/users/don-watkinshttps://opensource.com/users/sethhttps://opensource.com/users/jamesfhttps://opensource.com/users/seth
[b]: https://github.com/lujun9972
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/yearbook-haff-rx-linux-file-lead_0.png?itok=-i0NNfDC (Hand putting a Linux file folder into a drawer)
[2]: https://opensource.com/article/19/7/what-posix-richard-stallman-explains
[3]: https://opensource.com/article/19/6/understanding-linux-permissions
[4]: https://www.illumos.org/
[5]: https://en.wikipedia.org/wiki/FIFO_(computing_and_electronics)

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[#]: collector: (lujun9972)
[#]: translator: (wxy)
[#]: reviewer: (wxy)
[#]: publisher: ( )
[#]: url: ( )
[#]: subject: (Master the Linux 'ls' command)
[#]: via: (https://opensource.com/article/19/7/master-ls-command)
[#]: author: (Seth Kenlon https://opensource.com/users/seth)
精通 Linux 的 ls 命令
======
> Linux 的 ls 命令拥有数量惊人的选项，可以提供有关文件的重要信息。
![Hand putting a Linux file folder into a drawer][1]
`ls` 命令可以列出一个 [POSIX][2] 系统上的文件。这是一个简单的命令，但它经常被低估，不是它能做什么（因为它确实只做了一件事），而是你该如何优化对它的使用。
要知道在最重要的 10 个终端命令中，这个简单的 `ls` 命令可以排进前三，因为 `ls` 不会*只是*列出文件，它还会告诉你有关它们的重要信息。它会告诉你诸如拥有文件或目录的人、每个文件修改的时间、甚至是什么类型的文件。它的附带功能能让你了解你在哪里、附近有些什么，以及你可以用它们做什么。
如果你对 `ls` 的体验仅限于你的发行版在 `.bashrc` 中的别名，那么你可能错失了它。
### GNU 还是 BSD？
在了解 `ls` 的隐藏能力之前，你必须确定你正在运行哪个 `ls` 命令。有两个最流行的版本：包含在 GNU coreutils 包中的 GNU 版本，以及 BSD 版本。如果你正在运行 Linux，那么你很可能已经安装了 GNU 版本的 `ls`（LCTT 译注：几乎可以完全确定）。如果你正在运行 BSD 或 MacOS，那么你有的是 BSD 版本。本文会介绍它们的不同之处。
你可以使用 `--version` 选项找出你计算机上的版本：
```
$ ls --version
```
如果它返回有关 GNU coreutils 的信息，那么你拥有的是 GNU 版本。如果它返回一个错误，你可能正在运行的是 BSD 版本（运行 `man ls | head` 以确定）。
你还应该调查你的发行版可能具有哪些预设选项。终端命令的自定义通常放在 `$HOME/.bashrc` 或 `$HOME/.bash_aliases` 或 `$HOME/.profile` 中，它们是通过将 `ls` 别名化为更复杂的 `ls` 命令来完成的。例如：
```
alias ls='ls --color'
```
发行版提供的预设非常有用，但它们确实很难分辨出哪些是 `ls` 本身的特性，哪些是它的附加选项提供的。你要是想要运行 `ls` 命令本身而不是它的别名，你可以用反斜杠“转义”命令：
```
$ \ls
```
### 分类
单独运行 `ls` 会以适合你终端的列数列出文件：
```
$ ls ~/example
bunko        jdk-10.0.2
chapterize   otf2ttf.ff
despacer     overtar.sh
estimate.sh  pandoc-2.7.1
fop-2.3      safe_yaml
games        tt
```
这是有用的信息，但所有这些文件看起来基本相同，没有方便的图标来快速表示出哪个是目录、文本文件或图像等等。
使用 `-F`（或 GNU 上的长选项 `--classify`）以在每个条目之后显示标识文件类型的指示符：
```
$ ls ~/example
bunko         jdk-10.0.2/
chapterize*   otf2ttf.ff*
despacer*     overtar.sh*
estimate.sh   pandoc@
fop-2.3/      pandoc-2.7.1/
games/        tt*
```
使用此选项，终端中列出的项目使用简写符号来按文件类型分类：
* 斜杠（`/`）表示目录（或“文件夹”）。
* 星号（`*`）表示可执行文件。这包括二进制文件（编译代码）以及脚本（具有[可执行权限][3]的文本文件）。
* 符号（`@`）表示符号链接（或“别名”）。
* 等号（`=`）表示套接字。
* 在 BSD 上，百分号（`%`）表示<ruby>涂改<rt>whiteout</rt></ruby>（某些文件系统上的文件删除方法）。
* 在 GNU 上，尖括号（`>`）表示<ruby>门<rt>door</rt></ruby>（[Illumos][4] 和 Solaris上的进程间通信）。
* 竖线（`|`）表示 [FIFO][5] 管道。
  
这个选项的一个更简单的版本是 `-p`，它只区分文件和目录。
（LCTT 译注：在支持彩色的终端上，使用 `--color` 选项可以以不同的颜色来区分文件类型，但要注意如果将输出导入到管道中，则颜色消失。）
### 长列表
从 `ls` 获取“长列表”的做法是如此常见，以至于许多发行版将 `ll` 别名为 `ls -l`。长列表提供了许多重要的文件属性，例如权限、拥有每个文件的用户、文件所属的组、文件大小（以字节为单位）以及文件上次更改的日期：
```
$ ls -l
-rwxrwx---. 1 seth users         455 Mar  2  2017 estimate.sh
-rwxrwxr-x. 1 seth users         662 Apr 29 22:27 factorial
-rwxrwx---. 1 seth users    20697793 Jun 29  2018 fop-2.3-bin.tar.gz
-rwxrwxr-x. 1 seth users        6210 May 22 10:22 geteltorito
-rwxrwx---. 1 seth users         177 Nov 12  2018 html4mutt.sh
[...]
```
如果你不想以字节为单位，请添加 `-h` 标志（或 GNU 中的 `--human`）以将文件大小转换为更加人性化的表示方法：
```
$ ls --human
-rwxrwx---. 1 seth users    455 Mar  2  2017 estimate.sh
-rwxrwxr-x. 1 seth seth     662 Apr 29 22:27 factorial
-rwxrwx---. 1 seth users    20M Jun 29  2018 fop-2.3-bin.tar.gz
-rwxrwxr-x. 1 seth seth    6.1K May 22 10:22 geteltorito
-rwxrwx---. 1 seth users    177 Nov 12  2018 html4mutt.sh
```
要看到更少的信息，你可以带有 `-o` 选项只显示所有者的列，或带有 `-g` 选项只显示所属组的列：
```
$ ls -o
-rwxrwx---. 1 seth    455 Mar  2  2017 estimate.sh
-rwxrwxr-x. 1 seth    662 Apr 29 22:27 factorial
-rwxrwx---. 1 seth    20M Jun 29  2018 fop-2.3-bin.tar.gz
-rwxrwxr-x. 1 seth   6.1K May 22 10:22 geteltorito
-rwxrwx---. 1 seth    177 Nov 12  2018 html4mutt.sh
```
也可以将两个选项组合使用以显示两者。
### 时间和日期格式
`ls` 的长列表格式通常如下所示：
```
-rwxrwx---. 1 seth users         455 Mar  2  2017 estimate.sh
-rwxrwxr-x. 1 seth users         662 Apr 29 22:27 factorial
-rwxrwx---. 1 seth users    20697793 Jun 29  2018 fop-2.3-bin.tar.gz
-rwxrwxr-x. 1 seth users        6210 May 22 10:22 geteltorito
-rwxrwx---. 1 seth users         177 Nov 12  2018 html4mutt.sh
```
月份的名字不便于排序，无论是通过计算还是识别（取决于你的大脑是否倾向于喜欢字符串或整数）。你可以使用 `--time-style` 选项和格式名称更改时间戳的格式。可用格式为：
* `full-iso`：ISO 完整格式（1970-01-01 21:12:00）
* `long-iso`：ISO 长格式（1970-01-01 21:12）
* `iso`：iso 格式（01-01 21:12）
* `locale`：本地化格式（使用你的区域设置）
* `posix-STYLE`：POSIX 风格（用区域设置定义替换 `STYLE`）
你还可以使用 `date` 命令的正式表示法创建自定义样式。
### 按时间排序
通常，`ls` 命令按字母顺序排序。你可以使用 `-t` 选项根据文件的最近更改的时间（最新的文件最先列出）进行排序。
例如：
```
$ touch foo bar baz
$ ls
bar  baz  foo
$ touch foo
$ ls -t
foo bar baz
```
### 列出方式
`ls` 的标准输出平衡了可读性和空间效率，但有时你需要按照特定方式排列的文件列表。
要以逗号分隔文件列表，请使用 `-m`：
```
ls -m ~/example
bar, baz, foo
```
要强制每行一个文件，请使用 `-1` 选项（这是数字 1，而不是小写的 L）：
```
$ ls -1 ~/bin/
bar
baz
foo
```
要按文件扩展名而不是文件名对条目进行排序，请使用 `-X`（这是大写 X）：
```
$ ls
bar.xfc  baz.txt  foo.asc
$ ls -X
foo.asc  baz.txt  bar.xfc
```
### 隐藏杂项
在某些 `ls` 列表中有一些你可能不关心的条目。例如，元字符 `.` 和 `..` 分别代表“本目录”和“父目录”。如果你熟悉在终端中如何切换目录，你可能已经知道每个目录都将自己称为 `.`，并将其父目录称为 `..`，因此当你使用 `-a` 选项显示隐藏文件时并不需要它经常提醒你。
要显示几乎所有隐藏文件（`.` 和 `..` 除外），请使用 `-A` 选项：
```
$ ls -a
.
..
.android
.atom
.bash_aliases
[...]
$ ls -A
.android
.atom
.bash_aliases
[...]
```
有许多优秀的 Unix 工具有保存备份文件的传统，它们会在保存文件的名称后附加一些特殊字符作为备份文件。例如，在 Vim 中，备份会以在文件名后附加 `~` 字符的文件名保存。
这些类型的备份文件已经多次使我免于愚蠢的错误，但是经过多年享受它们提供的安全感后，我觉得不需要用视觉证据来证明它们存在。我相信 Linux 应用程序可以生成备份文件（如果它们声称这样做的话），我很乐意相信它们存在 —— 而不用必须看到它们。
要隐藏备份文件，请使用 `-B` 或 `--ignore-backups` 隐藏常用备份格式（此选项在 BSD 的 `ls` 中不可用）：
```
$ ls
bar.xfc  baz.txt  foo.asc~  foo.asc
$ ls -B
bar.xfc  baz.txt  foo.asc
```
当然，备份文件仍然存在；它只是过滤掉了，你不必看到它。
除非另有配置，GNU Emacs 在文件名的开头和结尾添加哈希字符（`＃`）来保存备份文件（`#file＃`）。其他应用程序可能使用不同的样式。使用什么模式并不重要，因为你可以使用 `--hide` 选项创建自己的排除项：
```
$ ls
bar.xfc  baz.txt  #foo.asc#  foo.asc
$ ls --hide="#*#"
bar.xfc  baz.txt  foo.asc
```
### 递归地列出目录
除非你在指定目录上运行 `ls`，否则子目录的内容不会与 `ls` 命令一起列出：
```
$ ls -F
example/  quux*  xyz.txt
$ ls -R
quux  xyz.txt
./example:
bar.xfc  baz.txt  #foo.asc#  foo.asc
```
### 使用别名使其永久化
`ls` 命令可能是 shell 会话期间最常使用的命令。这是你的眼睛和耳朵，为你提供上下文信息和确认命令的结果。虽然有很多选项很有用，但 `ls` 之美的一部分就是简洁：两个字符和回车键，你就知道你到底在哪里以及附近有什么。如果你不得不停下思考（更不用说输入）几个不同的选项，它会变得不那么方便，所以通常情况下，即使最有用的选项也不会用了。
解决方案是为你的 `ls` 命令添加别名，以便在使用它时，你可以获得最关心的信息。
要在 Bash shell 中为命令创建别名，请在主目录中创建名为 `.bash_aliases` 的文件（必须在开头包含 `.`）。 在此文件中，列出要创建的别名，然后是要为其创建别名的命令。例如：
```
alias ls='ls -A -F -B --human --color'
```
这一行导致你的 Bash shell 将 `ls` 命令解释为 `ls -A -F -B --human --color`。
你不必仅限于重新定义现有命令，还可以创建自己的别名：
```
alias ll='ls -l'
alias la='ls -A'
alias lh='ls -h'
```
要使别名起作用，shell 必须知道 `.bash_aliases` 配置文件存在。在编辑器中打开 `.bashrc` 文件（如果它不存在则创建它），并包含以下代码块：
```
if [ -e $HOME/.bash_aliases ]; then
    source $HOME/.bash_aliases
fi
```
每次加载 `.bashrc`（这是一个新的 Bash shell 启动的时候），Bash 会将 `.bash_aliases` 加载到你的环境中。你可以关闭并重新启动 Bash 会话，或者直接强制它执行此操作：
```
$ source ~/.bashrc
```
如果你忘了你是否有别名命令，`which` 命令可以告诉你：
```
$ which ls
alias ls='ls -A -F -B --human --color'
        /usr/bin/ls
```
如果你将 `ls` 命令别名为带有选项的 `ls` 命令，则可以通过将反斜杠前缀到 `ls` 前来覆盖你的别名。例如，在示例别名中，使用 `-B` 选项隐藏备份文件，这意味着无法使用 `ls` 命令显示备份文件。 可以覆盖该别名以查看备份文件：
```
$ ls
bar  baz  foo
$ \ls
bar  baz  baz~  foo
```
### 做一件事，把它做好
`ls` 命令有很多选项，其中许多是特定用途的或高度依赖于你所使用的终端。在 GNU 系统上查看 `info ls`，或在 GNU 或 BSD 系统上查看 `man ls` 以了解更多选项。
你可能会觉得奇怪的是，一个以每个工具“做一件事，把它做好”的前提而闻名的系统会让其最常见的命令背负 50 个选项。但是 `ls` 只做一件事：它列出文件，而这 50 个选项允许你控制接收列表的方式，`ls` 的这项工作做得非常、*非常*好。
--------------------------------------------------------------------------------
via: https://opensource.com/article/19/7/master-ls-command
作者：[Seth Kenlon][a]
选题：[lujun9972][b]
译者：[wxy](https://github.com/wxy)
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
[a]: https://opensource.com/users/sethhttps://opensource.com/users/sambocettahttps://opensource.com/users/scottnesbitthttps://opensource.com/users/sethhttps://opensource.com/users/marcobravohttps://opensource.com/users/sethhttps://opensource.com/users/don-watkinshttps://opensource.com/users/sethhttps://opensource.com/users/jamesfhttps://opensource.com/users/seth
[b]: https://github.com/lujun9972
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/yearbook-haff-rx-linux-file-lead_0.png?itok=-i0NNfDC (Hand putting a Linux file folder into a drawer)
[2]: https://opensource.com/article/19/7/what-posix-richard-stallman-explains
[3]: https://opensource.com/article/19/6/understanding-linux-permissions
[4]: https://www.illumos.org/
[5]: https://en.wikipedia.org/wiki/FIFO_(computing_and_electronics)