选题: The Fold Command Tutorial With Examples For Beginners

sources/tech/20180111 The Fold Command Tutorial With Examples For Beginners.md

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+The Fold Command Tutorial With Examples For Beginners
+======
+
+![](https://www.ostechnix.com/wp-content/uploads/2018/01/Fold-Command-2-720x340.png)
+
+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.
+
+In this brief tutorial, we are going to see the usage of fold command with practical examples.
+
+### The Fold Command Tutorial With Examples
+
+Fold command is the part of GNU coreutils package, so let us not bother about installation.
+
+The typical syntax of fold command:
+```
+fold [OPTION]... [FILE]...
+```
+
+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.
+
+[![][1]][2]
+
+To wrap each line in the above file to default width, run:
+```
+fold linux.txt
+```
+
+**80** columns per line is the default width. Here is the output of above command:
+
+[![][1]][3]
+
+As you can see in the above output, fold command has limited the output to a width of 80 characters.
+
+Of course, we can specify your preferred width, for example 50, like below:
+```
+fold -w50 linux.txt
+```
+
+Sample output would be:
+
+[![][1]][4]
+
+Instead of just displaying output, we can also write the output to a new file as shown below:
+```
+fold -w50 linux.txt > linux1.txt
+```
+
+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**.
+
+Let us check the contents of the new file:
+```
+cat linux1.txt
+```
+
+[![][1]][5]
+
+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.
+
+The following command wraps each line in a given file to width "50" and breaks the line at spaces:
+```
+fold -w50 -s linux.txt
+```
+
+Sample output:
+
+[![][1]][6]
+
+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.
+
+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.
+```
+fold -b20 linux.txt
+```
+
+Sample output:
+
+[![][1]][7]
+
+**Also read:**
+
++ [The Uniq Command Tutorial With Examples For Beginners][8]
+
+For more details, refer the man pages.
+```
+man fold
+```
+
+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!
+
+Cheers!
+
+
+
+--------------------------------------------------------------------------------
+
+via: https://www.ostechnix.com/fold-command-tutorial-examples-beginners/
+
+作者：[SK][a]
+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/
+[1]:data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
+[2]:http://www.ostechnix.com/wp-content/uploads/2018/01/fold-command-1.png ()
+[3]:http://www.ostechnix.com/wp-content/uploads/2018/01/fold-command-2.png ()
+[4]:http://www.ostechnix.com/wp-content/uploads/2018/01/fold-command-3-1.png ()
+[5]:http://www.ostechnix.com/wp-content/uploads/2018/01/fold-command-4.png ()
+[6]:http://www.ostechnix.com/wp-content/uploads/2018/01/fold-command-5-1.png ()
+[7]:http://www.ostechnix.com/wp-content/uploads/2018/01/fold-command-6-1.png ()
+[8]:https://www.ostechnix.com/uniq-command-tutorial-examples-beginners/