Merge pull request #13992 from lujun9972/add-MjAxOTA2MTAgRXhwYW5kIEFuZCBVbmV4cGFuZCBDb21tYW5kcyBUdXRvcmlhbCBXaXRoIEV4YW1wbGVzLm1kCg==

选题: 20190610 Expand And Unexpand Commands Tutorial With Examples

sources/tech/20190610 Expand And Unexpand Commands Tutorial With Examples.md

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+[#]: collector: (lujun9972)
+[#]: translator: ( )
+[#]: 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/