What does the cron expression 0 */8 * * * mean?

The cron expression 0 */8 * * * schedules a job to run every 8 Hours. The five fields represent: minute, hour, day of month, month, and day of week.

How do I schedule a cron job to run every 8 Hours?

Add this line to your crontab: 0 */8 * * * /path/to/command. Open your crontab for editing with crontab -e and paste the expression followed by your command.

How do I monitor a cron job that runs every 8 Hours?

Add a heartbeat check: 0 */8 * * * /path/to/script.sh && curl -fsS https://cronsignal.io/ping/YOUR_CHECK_ID. You'll be alerted if the job doesn't run on schedule.

Cron Every 8 Hours — 0 */8 * * *

Understanding the Expression

The cron expression 0 */8 * * * breaks down as follows:

Field	Value	Meaning
Minute	0	At minute 0
Hour	*/8	Every 8 hours
Day of month	*	Every day of the month
Month	*	Every month
Day of week	*	Every day of the week

Example Usage

Basic crontab entry

0 */8 * * * /path/to/your/script.sh

With output logging

0 */8 * * * /path/to/script.sh >> /var/log/script.log 2>&1

With monitoring

0 */8 * * * /path/to/script.sh && curl -fsS https://cronsignal.io/ping/YOUR_CHECK_ID

Common Use Cases for Every 8 Hours

Data synchronization: Sync data between systems periodically
Batch processing: Process accumulated records in batches
Report generation: Generate periodic status reports
Cleanup tasks: Remove temporary files and stale data

Platform Equivalents

The same schedule expressed across common platforms and schedulers:

Platform	Syntax
Linux crontab	`0 /8 * *`
GitHub Actions	`- cron: '0 /8 * *'`
systemd timer	`OnCalendar=0/8:00:00`
Kubernetes CronJob	`schedule: "0 /8 * *"`
AWS EventBridge	`cron(0 0/8 * * ? *)`

Timezone Considerations

0 */8 * * * fires at 00:00, 08:00, and 16:00 UTC. These are fixed clock times, not a rolling interval. A missed run is not retried — the next run is at the next fixed slot.

Common Mistakes

Fixed times, not rolling intervals: */8 means hours 0, 8, 16. A job running at 6 AM runs next at 8 AM (2 hours later), not 2 PM.
Exactly 3 runs per day: Midnight, 8 AM, and 4 PM (server timezone). Confirm this matches your cadence.
AWS step syntax: EventBridge requires 0/8 not */8: cron(0 0/8 * * ? *).

Cron Every 8 Hours