Crontab

To edit the jobs use:

crontab -e

To view all jobs by user:

crontab -l -u {username}

This is an example of the sytax.

*/5 * * * *  /home/user/test.pl

This is the time coding.

.---------------- 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 
|  |  |  |  |
*  *  *  *  *  command to be executed

Slash example: the following will run the script /home/user/test.pl every 5 minutes.

*/5 * * * *  /home/user/test.pl