What is a cron expression?

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

What does * mean in cron?

The asterisk (*) is a wildcard that means 'every' value for that field. For example, * in the hour field means 'every hour'.

How do I run a cron job every 5 minutes?

Use */5 * * * * — the */5 in the minute field means 'every 5th minute'. You can replace 5 with any interval.

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Minute

Hour

Day (M)

Month

Day (W)

⏰ Next 10 Run Times

⚡ Common Presets

📖 Cron Syntax Reference

Symbol	Meaning	Example
*	Any value (wildcard)	* in hour = every hour
,	List of values	1,15 in day = 1st and 15th
-	Range of values	1-5 in DOW = Monday to Friday
/	Step values	*/10 in minute = every 10 min
0-59	Minute	30 = at minute 30
0-23	Hour	14 = 2:00 PM
1-31	Day of month	1 = first day
1-12	Month	6 = June
0-7	Day of week (0 & 7 = Sun)	1 = Monday

Understanding Cron Expressions

Cron is a time-based job scheduler in Unix-like systems. A cron expression consists of 5 fields that define when a task should run:

┌───────────── minute (0-59)
│ ┌───────────── hour (0-23)
│ │ ┌───────────── day of month (1-31)
│ │ │ ┌───────────── month (1-12)
│ │ │ │ ┌───────────── day of week (0-7, Sun=0 or 7)
│ │ │ │ │
* * * * *

Common Cron Patterns

* * * * * — Every minute
0 * * * * — Every hour (at minute 0)
0 0 * * * — Every day at midnight
0 9 * * 1-5 — Every weekday at 9 AM
*/5 * * * * — Every 5 minutes
0 0 1 * * — First day of every month
0 0 * * 0 — Every Sunday at midnight

Special Characters

Asterisk (*) matches every value. Comma (,) separates list items (e.g., 1,3,5). Hyphen (-) defines ranges (e.g., 1-5). Slash (/) defines intervals (e.g., */10 = every 10th).

Crontab Commands

On Linux/macOS, use crontab -e to edit your cron jobs and crontab -l to list them. Each line in the crontab file is a cron expression followed by the command to run.

Cron in Modern Tools

Cron expressions are used beyond Unix crontab — they're supported in GitHub Actions (schedule trigger), AWS CloudWatch Events, Kubernetes CronJobs, CI/CD pipelines, and most task schedulers. The syntax is the same 5-field format.

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