What's the best way to check if a volume is mounted in a Bash script?

Solution 1:

Avoid using /etc/mtab because it may be inconsistent.

Avoid piping mount because it needn't be that complicated.

Simply:

if grep -qs '/mnt/foo ' /proc/mounts; then
    echo "It's mounted."
else
    echo "It's not mounted."
fi

(The space after the /mnt/foo is to avoid matching e.g. /mnt/foo-bar.)

Solution 2:

if mountpoint -q /mnt/foo 
then
   echo "mounted"
else
   echo "not mounted"
fi

or

mountpoint -q /mnt/foo && echo "mounted" || echo "not mounted"

Solution 3:

findmnt -rno SOURCE,TARGET "$1" avoids all the problems in the other answers. It cleanly does the job with just one command.

Other approaches have these downsides:

• grep -q and grep -s are an extra unnecessary step and aren't supported everywhere.
• /proc/\* isn't supported everywhere. (mountpoint is also based on proc).
• mountinfo is based on /proc/..
• cut -f3 -d' ' messes up spaces in path names
• Parsing mount's white space is problematic. It's man page now says:

.. listing mode is maintained for backward compatibility only.

For more robust and customizable output use findmnt(8), especially in your scripts.

Bash functions:

#These functions return exit codes: 0 = found, 1 = not found

isDevMounted () { findmnt --source "$1" >/dev/null;} #device only
isPathMounted() { findmnt --target "$1" >/dev/null;} #path   only
isMounted    () { findmnt          "$1" >/dev/null;} #device or path

#Usage examples:

if  isDevMounted "/dev/sda10";
   then echo "device is mounted"
   else echo "device is not mounted"
fi

if isPathMounted "/mnt/C";
   then echo   "path is mounted"
   else echo   "path is not mounted"
fi

#Universal (device OR path):
if isMounted     "/dev/sda10";
   then echo "device is mounted"
   else echo "device is not mounted"
fi

if isMounted     "/mnt/C";
   then echo   "path is mounted"
   else echo   "path is not mounted"
fi