HowTo use Crontab (Basic commands)

open the crontab editor:
# crontab -e

you can use this variables:

1 = Minute after the hour
2 = the hour you want it done
3 = Day of the Month
4 = Month of the Year
5 = Day of the week
6 = 'command you want to execute'
* = ALL

Example:
30 0 * * * /usr/local/aplication
It will run the application every day at 12:30 AM.
* * * - means all day of the month, all month of the year, all day of the week

Other crontab commands:
crontab -e opens the editor
crontab -l lists the contents of the crontab
crontab -r removes the crontab