To schedule a job to run in unattended mode one time only, you can use the at command. Scheduled jobs can be viewed with the atq command and deleted prior to execution with atrm . The crontab files are read by the cron service, which looks every minute to see if any jobs need run. Restrictions can be placed on who can use cron by creating a cron.allow file and only placing valid user names beneath there. Backups must be done in order to provide insurance for your data in the event of a catastrophe.
Backups can be full, or partial.
Differentials and incrementals cannot be mixed and matched, and you must use one or the other. As important as backups are, it is equally important that you verify that restores can be done on a regular basis. Only by testing the quality of the backups, and the restore procedure can you verify that you will be ready when an emergency does occur.