crontab - it is used for scheduling jobs, commands etc.The entry consist of 5 space Delimated fields followed by a command line.
crontab -e – it is used for scheduling crontab file
crontab -l - it is used for listing crontab jobs.
Eg: crontab -e
30 01 10 04 06 /usr/bin/find
Then start the daemon.
service crond start
chkconfig crond on
Here it executes the command find at 1:30 a.m on 10th april of every year when a Saturday falls off.