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 running automated tasks. For example, "0 9 * * 1-5" runs at 9 AM on weekdays.

How do I run a cron job every 5 minutes?

To run a cron job every 5 minutes, use the expression "*/5 * * * *". The */5 in the minute field means "every 5 minutes".

What does * mean in a cron expression?

The asterisk (*) in a cron expression means "every" or "any value". For example, * in the hour field means "every hour".

Cron job at 00:00, only on Friday

Use 0 0 * * FRI to run a cron job at 00:00, only on Friday. Check the expression and preview its next run times below.

This expression will run at 00:00, only on Friday

Quick presets:

0	*	*	FRI
				Day of the week (0 - 7) [Both 0 and 7 represent Sunday]
			Month (1 - 12)
		Day of the month (1 - 31)
	Hour (0 - 23)
Minute (0 - 59)

Asterisk (*) means "any" or "every".
an asterisk in the minute field means "every minute".
Comma (,) can be used to specify multiple values.
"1,15" in the minute field means "at 1 and 15 minutes past the hour".
Hyphen (-) defines a range.
"1-5" in the hour field means "every hour between 1am and 5am".
Slash (/) specifies increments.
"*/15" in the minute field would indicate "every 15 minutes".

Next scheduled times:

Fri, Sep 11, 2026, 00:00:00in 2 hours
Fri, Sep 18, 2026, 00:00:00in 7 days
Fri, Sep 25, 2026, 00:00:00in 14 days

Add this cron schedule to your crontab

Open your user crontab with crontab -e, then add the expression followed by the command you want to run:

0 0 * * FRI /path/to/your-command

Use absolute paths because cron runs with a smaller environment than your interactive shell. Confirm the entry was saved with crontab -l.

Make this cron job reliable

Cron starts commands but does not alert you when a command fails or a scheduled run never happens. Add a heartbeat after successful completion to detect silent failures.

0 0 * * FRI /path/to/your-command && curl -fsS --retry 3 https://oonchk.com/your-id

Read the complete cron job guide for setup and troubleshooting, browse common cron examples, or monitor this cron job.