Looking at it again, it's probably a good idea to extend that one-liner a little bit by throwing in a sync command, just to make sure that all zeroes get writte

Looking at it again, it's probably a good idea to extend that one-liner a little bit by throwing in a sync command, just to make sure that all zeroes get written to disk before deleting the fill-up file: dd if=/dev/zero of=/tmp/free_space_eater; sync; rm /tmp/free_space_eater