From LQWiki
The cron service allows arbitrary command-line tasks to be scheduled at various intervals: hourly, daily, weekly or monthly, with a granularity down to one minute. Tasks are specified by means of the crontab, which is stored on a per-user basis for execution by the cron daemon.
Depending on the setup, you might have to be in the cron group to create a crontab.
Scheduling jobs on computers which don't run permanently (home computers, computers in offices etc.) can use fcron either additionally to cron or even as exclusive scheduler.
This page is available under a