CronTab Posted by MOHAMMED ABDUL HAMEED on 8:08 AM

Cron is the system process which will automatically perform tasks for you according to a set schedule. The schedule is called the Crontab.

• crontab -e to edit crontab file
• crontab -l  to display crontab file 
• crontab -r to remove crontab file
• crontab -v to display the last time you edited your crontab file.
• crontab -u used in conjunction with other options, this option allows you to modify or view the crontab file of user, when available, only administrator can use this option.

• @yearly -> This will execute the system annual maintenance using annual-maintenance shell script at 00:00 on Jan 1st for every year.
• @monthly -> This will execute the shell script tape-backup at 00:00 on 1st of every month.
• @daily -> Using the @daily cron keyword, this will do a daily log file cleanup using cleanup-logs shell scriptat 00:00 on every day.
• @reboot -> Using the @reboot cron keyword, this will execute the specified command once after the machine got booted every time.