Scheduling
Scheduling with cron
Cron is used as the de-facto job scheduler for Unix.
Cron stands for "chronograph".
Every user can specify scripts or programs to run at specific time intervals in a text file called "crontab".
Example crontab file
Access/edit crontab file:
crontab -e
cron job definition
* * * * * command to execute
|--<Day of week (0:Sunday to 7)
|--<Month (1 - 12)
|--<Day of month (1 - 31)
|--<Hour (0 - 23)
|--<Minute (0 - 59)
cron shortcuts
| Entry | Description | Equivalant |
|---|---|---|
| @reboot | Run once at starttup | - |
| @yearly | Run once a year | 0 0 1 1 * |
| @annually | Same as @yearly | 0 0 1 1 * |
| @monthly | Run once a month | 0 0 1 * * |
| @weekly | Run once a week | 0 0 * * 0 |
| @daily | Run once a day | 0 0 * * * |
| @midnight | Same as @daily | 0 0 * * * |
| @hourly | Run once every hour | 0 * * * * |
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