Run a command with fstab-encoded arguments
fstab-decode COMMAND [ARGUMENT]...
fstab-decode decodes escapes in the specified ARGUMENTs and uses them to run COMMAND. The argument escaping uses the same rules as path escaping in /etc/fstab, /etc/mtab and /proc/mtab.
fstab-decode exits with status 127 if COMMAND can't be run. Otherwise it exits with the status returned by COMMAND.
fstab-decode umount $(awk '$3 == vfat { print $2 }' /etc/fstab)