IBM eServer Certification Study Guide - pSeries AIX System Administration

9.6. The cron daemon

The cron daemon runs shell commands at specified dates and times. The following event types are scheduled by the cron daemon:

• crontab command events

• at command events

• batch command events

• sync subroutine events

• ksh command events

• csh command events

The way these events are handled is specified in the /var/adm/cron/queuedefs file.

Regularly scheduled commands can be specified according to the instructions contained in the crontab files. You can submit your crontab file with the crontab command. Use the at command to submit commands that are to be run only once. Because the cron daemon never exits, it should be run only once.

The cron daemon examines crontab files and at command files only when the cron daemon is initialized. When ...