Parse cron expressions, preview schedules, get human-readable descriptions
A cron expression consists of 5 fields separated by spaces. Each field defines when the task should run.
* | Any value |
, | List separator (1,3,5) |
- | Range (1-5) |
/ | Step (*/5 = every 5th) |
Cron Tester lets you validate cron expressions and see upcoming task execution dates. Standard 5-field expressions are supported (minutes, hours, day of month, month, day of week), as well as special characters: * (any value), N-M (range), N/S (step), commas for lists.
Cron expressions use 5 fields: minute (0-59), hour (0-23), day of month (1-31), month (1-12), day of week (0-7). Special characters include * (any), / (step), - (range), and , (list). For example, */15 9-17 * * 1-5 means every 15 minutes during business hours on weekdays.
After configuring your cron schedule, set up heartbeat monitoring with dead man's switch to ensure cron jobs actually execute on time and don't silently fail.
A cron expression is a string of 5 fields (minute, hour, day of month, month, day of week) that defines a task execution schedule. Example: */5 * * * * — every 5 minutes. Used in Linux/Unix for automation.
Format: minute (0-59) hour (0-23) day (1-31) month (1-12) day_of_week (0-7). Special characters: * (any value), */N (every N), N-M (range), N,M (list). Example: 0 9 * * 1-5 — at 9:00 on weekdays.
Common schedules: * * * * * (every minute), 0 * * * * (every hour), 0 0 * * * (daily at midnight), 0 0 * * 0 (every Sunday), 0 0 1 * * (first day of every month).
Cron uses the server timezone (usually UTC). To change it: set TZ=Europe/Moscow variable in crontab. Or recalculate time manually. Our tester shows next runs in the specified timezone.
Check: 1) crontab -l shows the task, 2) script has execute permissions, 3) file paths are absolute (cron does not use PATH), 4) redirect output: >> /tmp/cron.log 2>&1, 5) set up heartbeat monitoring.