`0 */1 * * * if [[ -d /mnt/backup ]]; then rsync_tmbackup.sh /home /mnt/backup; fi` this is not valid for all sistems. Is not POSIX compilant. IMHO best soltuion is `if grep -qs /mnt/backup /proc/mounts; then rsync_tmbackup.sh /home /mnt/backup; fi`
Best regards and thanks for your script.