FreeBSD6 Unleashed

Using the Periodic Task Scheduler

The periodic command is like a souped-up version of cron. It’s designed to provide a framework for executing whole directories full of shell scripts at regular intervals specified in a crontab file. In FreeBSD’s default configuration, periodic is used for many housekeeping functions, controlled by a directory structure full of shell scripts located in /etc.

If you examine /etc/crontab, you will see three references to the periodic command:

# do daily/weekly/monthly maintenance
1       3       *       *       *           root periodic daily
15      4       *       *       6           root periodic weekly
30      5       1       *       *           root periodic monthly

The periodic command is invoked three times, with three different arguments: daily, weekly, and monthly. These arguments correspond to three ...