To schedule a cron job, type the following command at the UNIX / Linux shell prompt to edit the crontab file:
crontab -e
The format for cronjobs is:
+---------------- minute (0 - 59) | +------------- hour (0 - 23) | | +---------- day of month (1 - 31) | | | +------- month (1 - 12) | | | | +---- day of week (0 - 6) (Sunday=0 or 7) | | | | | * * * * * command to be executed