Cron Job Every 6 Months

Cron expression for every 6 months

0 0 1 */6 *

At 00:00, on day 1 of the month, every 6 months. It runs on 2 days a year.

Runs on 1 January and 1 July. 0 0 1 1,7 * is the same and clearer. It is a good schedule for rotating long-lived credentials or reminding the team to review certificates, domains and access lists.

Field by field

Examples

crontab

Run crontab -e and add:

0 0 1 */6 * /usr/local/bin/job.sh >> /var/log/job.log 2>&1

Kubernetes CronJob

apiVersion: batch/v1
kind: CronJob
metadata:
  name: my-job
spec:
  schedule: "0 0 1 */6 *"
  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: '0 0 1 */6 *'   # 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 6 months

[Timer]
OnCalendar=*-01,07-01 00:00:00
Persistent=true

[Install]
WantedBy=timers.target

Enable it with systemctl enable --now job.timer, and check the next runs with systemd-analyze calendar "*-01,07-01 00:00:00". Persistent=true runs a missed job after downtime, which cron can’t do.

AWS EventBridge

cron(0 0 1 1,7 ? *)

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: monthly and yearly

• Every month: 0 0 1 * *
• On the 15th of every month: 0 0 15 * *
• Twice a month: 0 0 1,15 * *
• On the last day of the month: 55 23 28-31 * *
• On the first Monday of the month: 0 9 1-7 * *
• Every quarter: 0 0 1 */3 *
• Every year: 0 0 1 1 *

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