Bash Script - umount a device, but don't fail if it's not mounted?

linux bash shell mount umount
Rory picture Rory · Sep 4, 2009 · Viewed 18.4k times · Source

I'm writing a bash script and I have errexit set, so that the script will die if any command doesn't return a 0 exit code, i.e. if any command doesn't complete successfully. This is to make sure that my bash script is robust.

I have to mount some filesystems, copy some files over, the umount it. I'm putting a umount /mnt/temp at the start so that it'll umount it before doing anything. However if it's not mounted then umount will fail and stop my script.

Is it possible to do a umount --dont-fail-if-not-mounted /mnt/temp? So that it will return 0 if the device isn't mounted? Like rm -f?

Answer

Andy Ross picture Andy Ross · Sep 4, 2009

The standard trick to ignore the return code is to wrap the command in a boolean expression that always evaluates to success:

umount .... || /bin/true

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