Enable Crontab

Giving Crontab permission to new os user

Login as root

Goto /etc/cron.d directory

Add the user entry (ex. ota ) in cron.allow file

Note: if cron.allow files doesn't exists then create it

Login as o/s user

Set the editor in .profile or .bash_profile

Example: EDITOR=vi;export EDITOR

Now you can schedule cron jobs.


To setup cronjob
crontab -l( list current jobs in cron)
crontab -e ( edit current jobs in cron)

_1_ _2_ _3_ _4_ _5_ executable_or_job
Where
1 – Minutes (0-59)
2 – Hours ( 0-24)
3 – day of month ( 1- 31 )
4 – Month ( 1-12)
5 – A day of week ( 0- 6 ) 0 -> sunday 1-> monday

e.g. 0 3 * * 6 Means run job at 3AM every saturday

This is useful for scheduling tablespace threshold, ftp, rman backup or removed old log files, or other scripts regularly.

Sample Scheduled backup:

$ crontab –l 

OTA Database:
50	23	*	*	0,2,3,6	/u01/ota/dailyexp_ota.sh
50	23	*	*	1,4	/u01/ota/offbkup_ota.sh
15	14	*	*	0,1,2,3,4,6	/u01/ota/morning_arch.sh