Linux Shell Scripting Cookbook - Second Edition

Scheduling with cron

It is a common requirement to schedule execution of scripts at a given time or at given time intervals. The GNU/Linux system comes with different utilities for scheduling tasks. cron is such a utility that allows tasks to automatically run in the background of the system at regular intervals using the cron daemon. The cron utility makes use of a file called cron table that stores a list of schedules of scripts or commands to be executed and the time at which they are to be executed. A common example usage is that you can schedule downloads of files from the Internet during the free hours (certain ISPs provide free usage hours, usually, at night time). This way you won't be required to wake up in the night to start the download. ...