How to set Linux Cron Jobs?

How to set cron jobs in linux for every 3 hour , i do not know anything about linux handling

 

The syntax for a system wide cron job for every three hours is:
vi /etc/crontab

* */3 * * * user command;

Code (markup):

 

If you have any control panel then you can add cron jobs directly from there.

e.g. if you have cPanel then you will find "Cron Jobs" there. Select Standard and set job as per your requirement.

 

https://help.ubuntu.com/community/CronHowto

 

From a shell, try "crontab -e". This should pull up the current crontab for whatever user you were logged in as. For system-wide cron jobs, you can still use that command, just execute it as root. It's easy to specify which user a job should run as. For additional information, please refer to the Cron HOWTO in the Ubuntu Community Documentation.

 

sudo crontab -e ( as you don't want to receive "permission denied" )

 

You can use an external cron jobs service