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115 lines
4.0 KiB
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The Fold Command Tutorial With Examples For Beginners
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======
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Have you ever found yourself in a situation where you want to fold or break the output of a command to fit within a specific width? I have find myself in this situation few times while running VMs, especially the servers with no GUI. Just in case, if you ever wanted to limit the output of a command to a particular width, look nowhere! Here is where **fold** command comes in handy! The fold command wraps each line in an input file to fit a specified width and prints it to the standard output.
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In this brief tutorial, we are going to see the usage of fold command with practical examples.
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### The Fold Command Tutorial With Examples
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Fold command is the part of GNU coreutils package, so let us not bother about installation.
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The typical syntax of fold command:
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```
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fold [OPTION]... [FILE]...
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```
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Allow me to show you some examples, so you can get a better idea about fold command. I have a file named **linux.txt** with some random lines.
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[![][1]][2]
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To wrap each line in the above file to default width, run:
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```
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fold linux.txt
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```
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**80** columns per line is the default width. Here is the output of above command:
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[![][1]][3]
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As you can see in the above output, fold command has limited the output to a width of 80 characters.
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Of course, we can specify your preferred width, for example 50, like below:
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```
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fold -w50 linux.txt
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```
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Sample output would be:
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[![][1]][4]
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Instead of just displaying output, we can also write the output to a new file as shown below:
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```
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fold -w50 linux.txt > linux1.txt
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```
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The above command will wrap the lines of **linux.txt** to a width of 50 characters, and writes the output to new file named **linux1.txt**.
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Let us check the contents of the new file:
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```
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cat linux1.txt
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```
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[![][1]][5]
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Did you closely notice the output of the previous commands? Some words are broken between lines. To overcome this issue, we can use -s flag to break the lines at spaces.
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The following command wraps each line in a given file to width "50" and breaks the line at spaces:
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```
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fold -w50 -s linux.txt
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```
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Sample output:
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[![][1]][6]
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See? Now, the output is much clear. This command puts each space separated word in a new line and words with length > 50 are wrapped.
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In all above examples, we limited the output width by columns. However, we can enforce the width of the output to the number of bytes specified using **-b** option. The following command breaks the output at 20 bytes.
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```
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fold -b20 linux.txt
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```
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Sample output:
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[![][1]][7]
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**Also read:**
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+ [The Uniq Command Tutorial With Examples For Beginners][8]
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For more details, refer the man pages.
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```
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man fold
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```
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And, that's for now folks. You know now how to use fold command to limit the output of a command to fit in a specific width. I hope this was useful. We will be posting more useful guides everyday. Stay tuned!
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Cheers!
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--------------------------------------------------------------------------------
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via: https://www.ostechnix.com/fold-command-tutorial-examples-beginners/
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作者：[SK][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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[1]:data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
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[2]:http://www.ostechnix.com/wp-content/uploads/2018/01/fold-command-1.png
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[3]:http://www.ostechnix.com/wp-content/uploads/2018/01/fold-command-2.png
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[4]:http://www.ostechnix.com/wp-content/uploads/2018/01/fold-command-3-1.png
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[5]:http://www.ostechnix.com/wp-content/uploads/2018/01/fold-command-4.png
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[6]:http://www.ostechnix.com/wp-content/uploads/2018/01/fold-command-5-1.png
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[7]:http://www.ostechnix.com/wp-content/uploads/2018/01/fold-command-6-1.png
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[8]:https://www.ostechnix.com/uniq-command-tutorial-examples-beginners/
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