Cron Notes

Here's the format

 .---------------- minute (0 - 59) 
 |  .------------- hour (0 - 23)
 |  |  .---------- day of month (1 - 31)
 |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ... 
 |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7)  OR sun,mon,tue,wed,thu,fri,sat 
 |  |  |  |  |
 *  *  *  *  *  

Notes...

a star means every value, so start in minute means every minute... Sooo...

* * * 1,7 * /biannual.backupscript #this ran every minute on jan 1 and july 1
0 0 1 1,7 * /biannual.backupscript #specify a 12:00 am on the first of the month

Easy examples

$crontab -e

* * * * 0 /usr/local/sbin/myscripts/mycrontabs/backupWeekly
* * 1 * * /usr/local/sbin/myscripts/mycrontabs/backupMonthly
* * 1,15 * * /usr/local/sbin/myscripts/mycrontabs/backupFtp

Edit cron jobs for this user

crontab -e

Edit cron jobs for the system

vi /etc/cron

Cron will send error messages to the user who run the script!

Run at 7:30 mon-fri

30 7 * * 1-5  /home/john/crons/asdf