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158 lines
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158 lines
4.4 KiB
Markdown
[#]: collector: (lujun9972)
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[#]: translator: ( )
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[#]: reviewer: ( )
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[#]: publisher: ( )
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[#]: url: ( )
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[#]: subject: (Expand And Unexpand Commands Tutorial With Examples)
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[#]: via: (https://www.ostechnix.com/expand-and-unexpand-commands-tutorial-with-examples/)
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[#]: author: (sk https://www.ostechnix.com/author/sk/)
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Expand And Unexpand Commands Tutorial With Examples
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======
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![Expand And Unexpand Commands Explained][1]
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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**.
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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.
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### Expand command examples
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Like I already mentioned, the Expand command replaces TAB characters in a file with SPACE characters.
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Now, let us convert tabs to spaces in the ostechnix.txt file and write the result to standard output using command:
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```
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$ expand ostechnix.txt
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```
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If you don’t want to display the result in standard output, just upload it to another file like below.
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```
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$ expand ostechnix.txt>output.txt
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```
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We can also convert tabs to spaces, reading from standard input. To do so, just run “expand” command without mentioning the source file name:
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```
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$ expand
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```
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Just type the text and hit ENTER to convert tabs to spaces. Press **CTRL+C** to quit.
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If you do not want to convert tabs after non blanks, use **-i** flag like below.
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```
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$ expand -i ostechnix.txt
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```
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We can also have tabs a certain number of characters apart, not 8 (the default value):
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```
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$ expand -t=5 ostechnix.txt
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```
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You can even mention multiple tab positions with comma separated like below.
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```
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$ expand -t 5,10,15 ostechnix.txt
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```
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Or,
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```
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$ expand -t "5 10 15" ostechnix.txt
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```
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For more details, refer man pages.
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```
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$ man expand
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```
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### Unexpand Command Examples
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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.
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To convert blanks (spaces, of course) in a file to tabs and write the output to stdout, do:
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```
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$ unexpand ostechnix.txt
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```
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If you want to write the output in a file instead of just displaying it to stdout, use this command:
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```
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$ unexpand ostechnix.txt>output.txt
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```
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Convert blanks to tabs, reading from standard output:
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```
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$ unexpand
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```
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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:
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```
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$ unexpand -a ostechnix.txt
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```
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To convert only leading sequences of blanks (Please note that it overrides **-a** ):
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```
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$ unexpand --first-only ostechnix.txt
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```
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Have tabs a certain number of characters apart, not **8** (enables **-a** ):
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```
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$ unexpand -t 5 ostechnix.txt
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```
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Similarly, we can mention multiple tab positions with comma separated like below.
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```
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$ unexpand -t 5,10,15 ostechnix.txt
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```
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Or,
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```
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$ unexpand -t "5 10 15" ostechnix.txt
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```
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For more details, refer man pages.
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```
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$ man unexpand
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```
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* * *
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**Suggested read:**
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* [**The Fold Command Tutorial With Examples For Beginners**][2]
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* * *
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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.
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--------------------------------------------------------------------------------
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via: https://www.ostechnix.com/expand-and-unexpand-commands-tutorial-with-examples/
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作者：[sk][a]
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选题：[lujun9972][b]
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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) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://www.ostechnix.com/author/sk/
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[b]: https://github.com/lujun9972
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[1]: https://www.ostechnix.com/wp-content/uploads/2019/05/Expand-And-Unexpand-Commands-720x340.png
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[2]: https://www.ostechnix.com/fold-command-tutorial-examples-beginners/
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