cheat sheets.

To edit the crontab of the current user:
$ crontab -e

To display the crontab of the current user:
$ crontab -l 

To remove the crontab of the current user:
$ crontab -r

Basic file format:

*     *   *   *    *  command to be executed
-     -    -    -    -
|     |     |     |     |
|     |     |     |     +----- day of week (0 - 6) (Sunday=0)
|     |     |     +------- month (1 - 12)
|     |     +--------- day of month (1 - 31)
|     +----------- hour (0 - 23)
+------------- min (0 - 59)