With crontab you can schedule tasks to be run in regular intervals. To do this, you need to know the crontab format. This tutorial describes briefly about the format of a crontab.
To edit your crontab, open it with your favorite text editor:
$ vim /etc/crontab
The crontab consists of lines each representing a scheduled script, for example:
5 10 6 3 * /home/user/script.sh
This script would run at every 6th of March at 10:05 AM, because
5stands for minute (0 to 59)
10stands for hour (0 to 23)
6stands for day (1 to 31)
3stands for month (1 to 12)
* stands for week day (0 to 7, where 0 and 7 both represent Sunday). If we would modify our line as follows:
5 10 6 3 4 /home/user/script.sh
This script would run at every Thu 6th of March at 10:05 AM. Note! Be aware that not every year the 6th of March is Thursday.
Examples above described how to set cron job to run in a specific time. If you want to schedule it differently, you can check following articles: