Linux Shell Scripting Cookbook - Third Edition

Scheduling with a cron

The GNU/Linux system supports several utilities for scheduling tasks. The cron utility is the most widely supported. It allows you to schedule tasks to be run in the background at regular intervals. The cron utility uses a table (crontab) with a list of scripts or commands to be executed and the time when they are to be executed.

Cron is used to schedule system housekeeping tasks, such as performing backups, synchronizing the system clocking with ntpdate, and removing temporary files.

A regular user might use cron to schedule Internet downloads to happen late at night when their ISP allows drop caps and the available bandwidth is higher.