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Needs a user only in system cron files ( /etc/cron.d/local )
# * * * * * [user] command to execute # │ │ │ │ │ # │ │ │ │ │ # │ │ │ │ └───── day of week (0 - 6) (0 to 6 are Sunday to Saturday, or use names; 7 is Sunday, the same as 0) # │ │ │ └────────── month (1 - 12) # │ │ └─────────────── day of month (1 - 31) # │ └──────────────────── hour (0 - 23) # └───────────────────────── min (0 - 59)
To test a system cron file save - then:
$ systemctl restart cron $ systemctl status cron
Errors will show up. (if editing a user cronfile via crontab -e it is tested at save.
| Entry | Description | Equivalent to |
|---|---|---|
| @yearly (or @annually) | Run once a year at midnight of January 1 | 0 0 1 1 * |
| @monthly | Run once a month at midnight of the first day of the month | 0 0 1 * * |
| @weekly | Run once a week at midnight on Sunday | 0 0 * * 0 |
| @daily | Run once a day at midnight | 0 0 * * * |
| @hourly | Run once an hour at the beginning of the hour | 0 * * * * |
| @reboot | Run at startup | @reboot |
/etc/cron.d is scanned every minute for changes - so if you make a change to run at the next minute it will fail - push it to two minutes.