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[#]: collector: (lujun9972)
[#]: translator: (geekpi)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
[#]: subject: (Expand And Unexpand Commands Tutorial With Examples)
[#]: via: (https://www.ostechnix.com/expand-and-unexpand-commands-tutorial-with-examples/)
[#]: author: (sk https://www.ostechnix.com/author/sk/)
Expand And Unexpand Commands Tutorial With Examples
======
![Expand And Unexpand Commands Explained][1]
This guide explains two Linux commands namely **Expand** and **Unexpand** with practical examples. For those wondering, the Expand and Unexpand commands are used to replace TAB characters in files with SPACE characters and vice versa. There is also a command called “Expand” in MS-DOS, which is used to expand a compressed file. But the Linux Expand command simply converts the tabs to spaces. These two commands are part of **GNU coreutils** and written by **David MacKenzie**.
For the demonstration purpose, I will be using a text file named “ostechnix.txt” throughout this guide. All commands given below are tested in Arch Linux.
### Expand command examples
Like I already mentioned, the Expand command replaces TAB characters in a file with SPACE characters.
Now, let us convert tabs to spaces in the ostechnix.txt file and write the result to standard output using command:
```
$ expand ostechnix.txt
```
If you don’t want to display the result in standard output, just upload it to another file like below.
```
$ expand ostechnix.txt>output.txt
```
We can also convert tabs to spaces, reading from standard input. To do so, just run “expand” command without mentioning the source file name:
```
$ expand
```
Just type the text and hit ENTER to convert tabs to spaces. Press **CTRL+C** to quit.
If you do not want to convert tabs after non blanks, use **-i** flag like below.
```
$ expand -i ostechnix.txt
```
We can also have tabs a certain number of characters apart, not 8 (the default value):
```
$ expand -t=5 ostechnix.txt
```
You can even mention multiple tab positions with comma separated like below.
```
$ expand -t 5,10,15 ostechnix.txt
```
Or,
```
$ expand -t "5 10 15" ostechnix.txt
```
For more details, refer man pages.
```
$ man expand
```
### Unexpand Command Examples
As you may have already guessed, the **Unexpand** command will do the opposite of the Expand command. I.e It will convert SPACE charatcers to TAB characters. Let me show you a few examples to learn how to use Unexpand command.
To convert blanks (spaces, of course) in a file to tabs and write the output to stdout, do:
```
$ unexpand ostechnix.txt
```
If you want to write the output in a file instead of just displaying it to stdout, use this command:
```
$ unexpand ostechnix.txt>output.txt
```
Convert blanks to tabs, reading from standard output:
```
$ unexpand
```
By default, Unexpand command will only convert the initial blanks. If you want to convert all blanks, instead of just initial blanks, use **-a** flag:
```
$ unexpand -a ostechnix.txt
```
To convert only leading sequences of blanks (Please note that it overrides **-a** ):
```
$ unexpand --first-only ostechnix.txt
```
Have tabs a certain number of characters apart, not **8** (enables **-a** ):
```
$ unexpand -t 5 ostechnix.txt
```
Similarly, we can mention multiple tab positions with comma separated like below.
```
$ unexpand -t 5,10,15 ostechnix.txt
```
Or,
```
$ unexpand -t "5 10 15" ostechnix.txt
```
For more details, refer man pages.
```
$ man unexpand
```
* * *
**Suggested read:**
* [**The Fold Command Tutorial With Examples For Beginners**][2]
* * *
When you working on large number of files, the Expand and Unexpand commands could be very helpful to replace unwanted TAB characters with SPACE characters and vice versa.
--------------------------------------------------------------------------------
via: https://www.ostechnix.com/expand-and-unexpand-commands-tutorial-with-examples/
作者：[sk][a]
选题：[lujun9972][b]
译者：[译者ID](https://github.com/译者ID)
校对：[校对者ID](https://github.com/校对者ID)
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
[a]: https://www.ostechnix.com/author/sk/
[b]: https://github.com/lujun9972
[1]: https://www.ostechnix.com/wp-content/uploads/2019/05/Expand-And-Unexpand-Commands-720x340.png
[2]: https://www.ostechnix.com/fold-command-tutorial-examples-beginners/

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[#]: collector: (lujun9972)
[#]: translator: (geekpi)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
[#]: subject: (Expand And Unexpand Commands Tutorial With Examples)
[#]: via: (https://www.ostechnix.com/expand-and-unexpand-commands-tutorial-with-examples/)
[#]: author: (sk https://www.ostechnix.com/author/sk/)
expand 与 unexpand 命令教程与示例
======
![Expand And Unexpand Commands Explained][1]
本指南通过实际的例子解释两个 Linux 命令，即 **expand** 和 **unexpand**。对于好奇的人，expand 和 unexpand 命令用于将文件中的 TAB 字符替换为空格，反之亦然。在 MS-DOS 中也有一个名为 “expand” 的命令，它用于解压压缩文件。但 Linux expand 命令只是将 tab 转换为空格。这两个命令是 **GNU coreutils** 的一部分，由 **David MacKenzie** 编写。
为了演示，我将在本文使用名为 “ostechnix.txt” 的文本文件。下面给出的所有命令都在 Arch Linux 中进行测试。
### expand 命令示例
与我之前提到的一样，expand 命令使用空格替换文件中的 TAB 字符。
现在，让我们将ostechnix.txt 中的 tab 转换为空格，并将结果写入标准输出：
```
$ expand ostechnix.txt
```
如果你不想在标准输出中显示结果，只需将其写入另一个文件，如下所示。
```
$ expand ostechnix.txt>output.txt
```
我们还可以将标准输入中的 tab 转换为空格。为此，只需运行 “expand” 命令而不带文件名：
```
$ expand
```
只需输入文本并按回车键就能将 tab 转换为空格。按 **CTRL+C** 退出。
如果你不想在非空白符后转换 tab，请使用 **-i** 标记，如下所示。
```
$ expand -i ostechnix.txt
```
我们还可以设置每个 tab 为指定数字的宽度，而不是 8（默认值）。
```
$ expand -t=5 ostechnix.txt
```
我们甚至可以使用逗号分隔指定多个 tab 位置，如下所示
```
$ expand -t 5,10,15 ostechnix.txt
```
或者，
```
$ expand -t "5 10 15" ostechnix.txt
```
有关更多详细信息，请参阅手册页。
```
$ man expand
```
### unexpand 命令示例
正如你可能已经猜到的那样，**unexpand** 命令将执行与 expand 命令相反的操作。即它会将空格转换为 TAB。让我向你展示一些例子，以了解如何使用 unexpand 命令。
要将文件中的空白（当然是空格）转换为 tab 并将输出写入标准输出，请执行以下操作：
```
$ unexpand ostechnix.txt
```
如果要将输出写入文件而不是仅将其显示到标准输出，请使用以下命令：
```
$ unexpand ostechnix.txt>output.txt
```
从标准输出读取内容，将空格转换为制表符：
```
$ unexpand
```
默认情况下，unexpand 命令仅转换初始的空格。如果你想转换所有空格而不是只是初始空格，请使用 **-a** 标志：
```
$ unexpand -a ostechnix.txt
```
仅转换开头的空白（请注意它会覆盖 **-a**）：
```
$ unexpand --first-only ostechnix.txt
```
使多少个空格替换成一个 tab，而不是 **8**（启用 **-a** ）：
```
$ unexpand -t 5 ostechnix.txt
```
相似地，我们可以使用逗号分隔指定多个tab的位置。
```
$ unexpand -t 5,10,15 ostechnix.txt
```
或者，
```
$ unexpand -t "5 10 15" ostechnix.txt
```
有关更多详细信息，请参阅手册页。
```
$ man unexpand
```
在处理大量文件时，expand 和 unexpand 命令对于用空格替换不需要的 TAB 时非常有用，反之亦然。
--------------------------------------------------------------------------------
via: https://www.ostechnix.com/expand-and-unexpand-commands-tutorial-with-examples/
作者：[sk][a]
选题：[lujun9972][b]
译者：[geekpi](https://github.com/geekpi)
校对：[校对者ID](https://github.com/校对者ID)
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
[a]: https://www.ostechnix.com/author/sk/
[b]: https://github.com/lujun9972
[1]: https://www.ostechnix.com/wp-content/uploads/2019/05/Expand-And-Unexpand-Commands-720x340.png