Cheat Sheets · Cron Cheat Sheet · Cron Every 6 Hours — Crontab Example

Cron Every 6 Hours — Crontab Example

0 */6 * * *

Runs 4 times a day — at 00:00, 06:00, 12:00, 18:00.

Field by field

Field	Value	Meaning
`Minute`	`0`	At minute 0
`Hour`	`*/6`	Every 6th hour (0, 6, 12, 18)
`Day of month`	`*`	Every day
`Month`	`*`	Every month
`Day of week`	`*`	Every day of the week

Running 4 times daily (midnight, 6 AM, noon, 6 PM), this expression provides a steady pulse for heavy ETL jobs, anti-virus definition updates, and snapshot backups.

0 */6 * * * /usr/local/bin/db-snapshot.sh

Related schedules

0 */4 * * * Every 4 hours 0 */12 * * * Every 12 hours 0 0 * * * Daily at midnight

FAQ

Can I run at 03:00, 09:00, 15:00, 21:00?
Yes: use 0 3-23/6 * * * to shift the entire schedule by 3 hours.

Is this expression supported on all Linux distros?
Yes. The step syntax */6 is supported by Vixie cron, Cronie, systemd timers, and modern cloud schedulers.

What if a run takes 7 hours?
A second instance will launch. Protect against overlapping runs using flock -n /tmp/job.lock.

Stop memorizing — build it interactively

Try this schedule in the Cron Editor

Full reference: Cron Cheat Sheet