System Administration Guide: Advanced Administration

How the cron Daemon Handles Scheduling

The cron daemon manages the automatic scheduling of crontab commands. The role of the cron daemon is to check the /var/spool/cron/crontab directory for the presence of crontab files.

The cron daemon performs the following tasks at startup:

In much the same way, the cron daemon controls the scheduling of at files. These files are stored in the /var/spool/cron/atjobs directory. The cron daemon also listens for notifications from the crontab commands regarding submitted at jobs.