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Tags: command-line   bash   scripts  
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Title: Why combine commands on a single line in a Bash script?
ID: /2019/10/21/Why-combine-commands-on-a-single-line-in-a-Bash-script_
Created: October 21, 2019    Edited:  October 23, 2019
Upload: November 24, 2022    Layout:  post
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Why we sometimes like to use it

When we are writing answers here in Ask Ubuntu it is helpful to put them into one line which people can cut and paste into their terminal easier. For example:

$ CurrDir=$PWD ; cd /bin ; ls -la dd ; cd "$CurrDir"

-rwxr-xr-x 1 root root 72632 Mar  2  2017 dd

As mentioned earlier you could use && for the same effect but if there were errors above you could end up on the wrong directory. In this case ; is preferable to && that isn’t tested for success:

rick@alien:~/askubuntu$ CurrDir=$PWD && cd /bin && llllssss -la dd && cd "$CurrDir"

llllssss: command not found


Why we have to use it

There are some commands where you have to string multiple lines together. One case is the abbreviated if-commands-fi which must be one line. For example:

$ [[ 2 -eq 2 ]] && { echo 2 equals 2 ; echo setting three to 3 ; three=3 ; }

2 equals 2
setting three to 3
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