Cron Job Every Hour at Half Past

Cron expression for every hour at half past

30 * * * *

At 30 minutes past the hour. It runs 24 times a day, 8,760 times a year.

Runs at 00:30, 01:30, 02:30 and so on. Picking a minute other than :00 is a good habit for hourly jobs. So much work is scheduled at the top of the hour that shared databases, APIs and CI runners are busiest then.

Field by field

Examples

crontab

Run crontab -e and add:

30 * * * * /usr/local/bin/job.sh >> /var/log/job.log 2>&1

Kubernetes CronJob

apiVersion: batch/v1
kind: CronJob
metadata:
  name: my-job
spec:
  schedule: "30 * * * *"
  timeZone: "Etc/UTC"          # Kubernetes 1.27+
  concurrencyPolicy: Forbid    # skip a run if the last one is still going
  jobTemplate:
    spec:
      template:
        spec:
          containers:
            - name: job
              image: ghcr.io/acme/job:1.0
          restartPolicy: OnFailure

GitHub Actions

on:
  schedule:
    - cron: '30 * * * *'   # UTC

GitHub evaluates schedules in UTC, and runs can start several minutes late at busy times.

systemd timer

# /etc/systemd/system/job.timer
[Unit]
Description=Run job.service every hour at half past

[Timer]
OnCalendar=*-*-* *:30:00
Persistent=true

[Install]
WantedBy=timers.target

Enable it with systemctl enable --now job.timer, and check the next runs with systemd-analyze calendar "*-*-* *:30:00". Persistent=true runs a missed job after downtime, which cron can’t do.

AWS EventBridge

cron(30 * * * ? *)

EventBridge cron has six fields (the last is the year), uses ? in either the day-of-month or the day-of-week field, and numbers weekdays from 1 (Sunday) to 7. Rules run in UTC; EventBridge Scheduler also accepts a time zone.

Similar schedules: hourly

• Every hour: 0 * * * *
• Every 2 hours: 0 */2 * * *
• Every 3 hours: 0 */3 * * *
• Every 4 hours: 0 */4 * * *
• Every 6 hours: 0 */6 * * *
• Every 8 hours: 0 */8 * * *
• Every 12 hours: 0 */12 * * *
• Every hour during business hours: 0 9-17 * * 1-5

Have a different schedule? Paste any expression into the Cron Expression Generator, or browse all cron examples.

Sources

• POSIX: crontab
• crontab(5) manual page
• Kubernetes docs: CronJob
• GitHub Actions docs: schedule event
• systemd.time(7): calendar events
• AWS docs: EventBridge Scheduler cron expressions

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Frequently asked questions