Cron job format

Posted by Admin on February 11, 2009
IT

So if you’re not a linux or UNIX geek, you’re probably wondering what on earth this is.  Well, simple enough, Cron is a thing in Linux or UNIX operating systems that will do stuff on a schedule.  Specifically, it can execute a script at a given time on a given day, recurringly.  (Is recurringly a word?)   So Cron is really good for stuff like backups, for example.

I’m writing this post because I’m tired of having to Google the syntax every time I want to edit my Cront settings, so I’ve put it here… so I can search my blog instead 🙂

Bye for now.

*     *   *   *    *  command to be executed
–     –    –    –    –
|     |     |     |     |
|     |     |     |     +—– day of week (0 – 6) (Sunday=0)
|     |     |     +——- month (1 – 12)
|     |     +——— day of month (1 – 31)
|     +———– hour (0 – 23)
+————- min (0 – 59)

Changing the parameter values as below will cause this command to run at different time schedule below :

min hour day/month month day/week Execution time
30 0 1 1,6,12 * — 00:30 Hrs  on 1st of Jan, June & Dec.

:

0 20 * 10 1-5 –8.00 PM every weekday (Mon-Fri) only in Oct.

:

0 0 1,10,15 * * — midnight on 1st ,10th & 15th of month

:

5,10 0 10 * 1 — At 12.05,12.10 every Monday & on 10th of every month
:


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