CRON(8) CRON(8) NAME cron - clock daemon SYNOPSIS auth/cron [ -c ] DESCRIPTION Cron executes commands at specified dates and times accord- ing to instructions in the files /cron/user/cron. It runs only on an authentication server. Option -c causes cron to create /cron/user and /cron/user/cron for the current user; it can be run from any Plan 9 machine. Blank lines and lines beginning with # in these files are ignored. Entries are lines with fields minute hour day month weekday host command Command is a string, which may contain spaces, that is passed to an rc(1) running on host for execution. The first five fields are integer patterns for minute 0-59 hour 0-23 day of month 1-31 month of year 1-12 day of week 0-6; 0=Sunday The syntax for these patterns is time : '*' | range range : number | number '-' number | range ',' range Each number must be in the appropriate range. Hyphens spec- ify inclusive ranges of valid times; commas specify lists of valid time ranges. To run the job, cron calls host and authenticates remote execution, equivalent to running rx host command (see con(1)). The user's profile is run with $service set to rx. If host is set to local, cron will run the command as user on the local machine without using rx. Cron is not a reliable service. It skips commands if it cannot reach host within two minutes, or if the cron daemon is not running at the appropriate time. EXAMPLES Page 1 Plan 9 (printed 10/14/24) CRON(8) CRON(8) Here is the job that mails system news. % cat /cron/upas/cron # send system news 15 8-17,21 * * * helix /mail/lib/mailnews % FILES /cron/lock lock file to prevent multiple crons running SOURCE /sys/src/cmd/auth/cron.c SEE ALSO con(1), rc(1) Page 2 Plan 9 (printed 10/14/24)