September 2000
Beginner
1312 pages
33h 47m
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/usr/sbin/cron
The cron (chronograph) command starts the cron system daemon that executes commands at specified dates and times. cron is started at system boot time through the /etc/rc2.d/s75cron run control script. The file /etc/cron.d/FIFO is used (among other things) as a lock file to prevent the execution of more than one instance of cron.
cron is not a user command and should never be executed directly. cron operations are scheduled and executed from crontab files in the directory /var/spool/cron/crontabs. Users can submit their own crontab file by using the crontab(1) command. Commands that are to be executed only once can be submitted with the at(1) command.
cron examines crontab or at command ...