Crontab

The crontab command, not to be confused within the /etc/crontab file, is used through the users of the system to schedule personal events. A cron files are stored under the /var/spool/cron directory. The administrators of system can control whether or not this facility exists on the system by the /etc/cron.deny or/etc/cron.allow files. All current cron jobs are listed with the crontab -l option. The -e option has to be used to make or edit a job and -r to remove a job

Syntax:

crontab [option] [username]

Practice

The given example example shows how to edit a crontab file for a user to run "welcome" at midnight of every Sunday.

#          crontab -e krishen

0 0 0 * * banner welcome > /dev/console

This denotes that the command should be run on the zeroth minute of the zeroth hour (midnight) of the zeroth day (Sunday) of every week.

At one the crontab file has been set up (and that of the system's, if the user is the root user), there is no necessity to worry about it again, until the configuration has to be changed.

For list the current crontab entries the following command should be used:

# crontab -l     [username]