Build, validate, and understand cron expressions with visual tools
Cron expressions are used to schedule tasks in Unix-like systems. They consist of five fields that specify when a command should be executed:
0 0 * * * - Daily at midnight
0 */2 * * * - Every 2 hours
30 9 * * 1-5 - 9:30 AM on weekdays
0 0 1 */3 * - Quarterly on 1st
*/15 * * * * - Every 15 minutes
0 9,17 * * * - 9 AM and 5 PM daily
0 0 * * 6,0 - Weekends at midnight
0 3 1,15 * * - 1st and 15th at 3 AM