FreeBSD® Unleashed

The cron Daemon

The scheduler in FreeBSD, as in most UNIX-type systems, is called cron. FreeBSD's cron program was written by Paul Vixie, and it is the standard version used in most distributions of Linux and other similar systems. Like any standalone daemon, it runs all the time, and looks at its input files (called crontab files) each minute to see if they have changed or if they contain a task it needs to execute that minute. The cron process itself never needs to be restarted; it will automatically read in any changes when it wakes up every minute.

There is a global crontab file (/etc/crontab) and a directory (/var/cron/tabs), in which individual users can create their own crontab files. It can be tempting to add your own scheduled jobs to ...