What is cron?
Cron is the time-based job scheduler used on Unix and Linux systems. A cron expression has five fields that define when a task runs: minute, hour, day of month, month, and day of week. This explainer reads those fields and describes the schedule in everyday language.
The five fields
- Minute — 0–59
- Hour — 0–23
- Day of month — 1–31
- Month — 1–12
- Day of week — 0–6 (Sunday = 0)
Special characters
*— every value.*/5— every 5th value (a step).1-5— a range.1,15,30— a specific list.
Example
0 9 * * 1-5 means “at 09:00, Monday through Friday” — a common weekday-morning schedule.
Limitations
- This explainer supports the standard 5-field format. Some systems add a seconds field or use shorthand like
@daily, which are not parsed here. - Always confirm the schedule on your actual system, especially around time zones and daylight saving.
Privacy: Parsing happens entirely in your browser.