Select the Job Scheduler tool from the Tool Menu in the Administration Workspace.
A cron expression is a string comprised of 6 or 7 fields separated by white space. Fields can contain any of the allowed values, along with various combinations of the allowed special characters for that field. The fields are as follows:
Field Name Mandatory Allowed Values Allowed Special Characters
Seconds YES 0-59 , - * /
Minutes YES 0-59 , - * /
Hours YES 0-23 , - * /
Day of month YES 1-31 , - * ? / L W
Month YES 1-12 or JAN-DEC , - * /
Day of week YES 1-7 or SUN-SAT , - * ? / L #
Year NO empty, 1970-2099 , - * /
So cron expressions can be as simple as this: * * * * ? *
or more complex, like this: 0/5 14,18,3-39,52 * ? JAN,MAR,SEP MON-FRI 2002-2010
For more information on cron expressions, see How do I create cron expressions?