What does the cron expression */30 * * * * mean?

The cron expression */30 * * * * schedules a job to run every 30 Minutes. The five fields represent: minute, hour, day of month, month, and day of week.

How do I schedule a cron job to run every 30 Minutes?

Add this line to your crontab: */30 * * * * /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 30 Minutes?

Add a heartbeat check: */30 * * * * /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 30 Minutes

Understanding the Expression

The cron expression */30 * * * * breaks down as follows:

Field	Value	Meaning
Minute	*/30	Every 30 minutes
Hour	*	Every hour
Day of month	*	Every day of the month
Month	*	Every month
Day of week	*	Every day of the week

Example Usage

Basic crontab entry

*/30 * * * * /path/to/your/script.sh

With output logging

*/30 * * * * /path/to/script.sh >> /var/log/script.log 2>&1

With monitoring

*/30 * * * * /path/to/script.sh && curl -fsS https://cronsignal.io/ping/YOUR_CHECK_ID

Common Use Cases for Every 30 Minutes

Real-time monitoring: Check system health and service availability
Queue processing: Process background job queues frequently
Cache warming: Keep caches fresh with regular updates
Metrics collection: Gather application and infrastructure metrics

Platform Equivalents

The same schedule expressed across common platforms and schedulers:

Platform	Syntax
Linux crontab	`/30 * * *`
GitHub Actions	`- cron: '/30 * * *'`
systemd timer	`OnCalendar=*:0/30`
Kubernetes CronJob	`schedule: "/30 * * *"`
AWS EventBridge	`cron(0/30 * * * ? *)`

Timezone Considerations

Every-30-minute jobs fire at :00 and :30 of every hour. Timezone-independent, but requires accurate system clock.

Common Mistakes

Two fixed runs per hour: */30 means minutes 0 and 30 — not a sliding 30-minute window from start.
Stagger multiple jobs: Offset with 5/30 (fires :05 and :35) to avoid minute-0 contention with other jobs.
AWS EventBridge: cron(0/30 * * * ? *) — 6-field format with ? for day-of-week.