Question 1

What is a cron expression?

Accepted Answer

A cron expression is a string of 5 fields (minute, hour, day-of-month, month, day-of-week) that defines a recurring schedule for automated tasks. For example, '0 9 * * 1-5' means every weekday at 9:00 AM.

Question 2

What does * mean in cron?

Accepted Answer

An asterisk (*) in a cron field means 'every valid value' for that field. For example, * in the minute field means the job runs every minute. 0 * * * * means every hour on the hour.

Question 3

What is the difference between cron day-of-month and day-of-week?

Accepted Answer

Day-of-month (field 3) is 1–31 and specifies which day of the month. Day-of-week (field 5) is 0–7 (0 and 7 = Sunday) and specifies which day of the week. If both are set, most cron implementations trigger if EITHER matches.

Field	Range	Special Values
Minute	0–59	, 0-30, /5 (every 5)
Hour	0–23	, 9-17 (business hours), /6
Day of Month	1–31	*, 1 (first), 15 (mid-month)
Month	1–12	*, 1-3 (Q1), 6,12
Day of Week	0–7 (0&7=Sun)	*, 1-5 (weekdays), 6,0 (wknd)

Cron Expression Builder

Cron Syntax Reference

Cron Expression Builder

Cron Syntax Reference

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