Cron Schedule Reference

Cron: Every 6 Hours

Run a cron job 4 times per day: midnight, 6 AM, noon, 6 PM.

0 */6 * * *

Every 6 Hours

Expression Breakdown

Minute

*/6

Hour

*/6

Day

Every day

Month

Every month

Weekday

Any day

Usage in Crontab

Add this line to your crontab (crontab -e):

# Every 6 Hours
0 */6 * * * /path/to/your/script.sh

With CronPing Monitoring

Add a curl ping to get alerted if your job fails or runs late:

# Every 6 Hours — with CronPing dead man's switch
0 */6 * * * /path/to/your/script.sh && curl -s https://cronping.anethoth.com/ping/YOUR_TOKEN

Common Use Cases

Database Backups

Automate pg_dump or mysqldump on this schedule

Cache Warming

Pre-compute expensive queries or API responses

Report Generation

Generate and email analytics reports

Health Checks

Ping endpoints and check service availability

Monitor Your Cron Jobs

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Frequently Asked Questions

What does 0 */6 * * * mean in cron?

Run a cron job 4 times per day: midnight, 6 AM, noon, 6 PM. This expression follows the standard 5-field cron syntax: minute, hour, day-of-month, month, day-of-week.

How do I add this to my crontab?

Run crontab -e in your terminal and add: 0 */6 * * * /path/to/your/command. Save and exit. Use crontab -l to verify.

How do I know if my cron job actually ran?

Check /var/log/syslog or /var/log/cron for execution logs. For reliable monitoring, use CronPing — it alerts you when a job misses its expected schedule.

What timezone does cron use?

Cron uses the system timezone by default. Check with timedatectl or set TZ=UTC in your crontab for consistency across servers.