Cron expression parser

How cron expressions work

A cron expression is a string of 5 space-separated fields that define a recurring schedule: minute hour day-of-month month day-of-week. Each field accepts a specific value, a wildcard (* = every), a range (1-5), a list (1,3,5), or a step value (*/15 = every 15 units).

Examples: 0 9 * * 1-5 = 9:00 AM on weekdays. */15 * * * * = every 15 minutes. 0 0 1 * * = midnight on the 1st of every month. 0 */2 * * * = every 2 hours. Day-of-week: 0 or 7 = Sunday, 1 = Monday, …, 6 = Saturday. Cron runs in the server's local timezone unless configured otherwise — always set timezone explicitly in production systems using CRON_TZ or system-level settings. Some platforms use 6-field cron (adding seconds as the first field) or 7-field (adding year at the end).