Try this, replace "/foo/bar" with the path to your mount point, and the echos with additional desired behaviour.

(I'm assuming you're writing a bash script on a Linux system)

if grep -qs '/foo/bar' /proc/mounts; then

    echo "/foo/bar mounted"

else

    echo "/foo/bar not mounted"

    return 1 || exit 1

fi

Put these commands below the shebang but before the start of the script. I hope this helps you!

Edit: I added a crapload of newlines to better show the indentation and newlines required for the script to work. Sorry it's ugly