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

The expression 0 * * ? * * means: at minute 0, hour *, day-of-month *, month ?, day-of-week *. Each field in the cron expression controls a different time component: minute, hour, day of month, month, and day of week.

How do I add 0 * * ? * * to my crontab?

Run crontab -e in your terminal to open your crontab editor. Add a new line: 0 * * ? * * /path/to/your/script.sh. Save and exit. Verify with crontab -l. Make sure your script is executable (chmod +x script.sh) and uses full paths for all commands.

What is the equivalent of 0 * * ? * * on Quartz / AWS / Kubernetes?

Quartz Scheduler: 0 * * ? ?. AWS EventBridge: cron(0 * ? ? * *). Kubernetes CronJob: schedule: "0 * * ? * *" (standard 5-field format). Each platform has slight syntax differences — use our dialect switcher above to get the exact expression.

What are common mistakes when using 0 * * ? * *?

Common pitfalls: (1) Cron uses a minimal PATH — always use full paths to commands and scripts. (2) Percent signs (%) must be escaped with backslash in crontab. (3) Cron runs in the system timezone — set CRON_TZ=UTC at the top of your crontab for consistent UTC scheduling. (4) Redirect output to prevent email spam: 0 * * ? * * /path/command >> /var/log/myjob.log 2>&1. (5) Test your cron expression with crontab.guru or our validator above before deploying.

Quartz Cron Expressions

Learn Quartz Scheduler cron syntax. 7-field format with seconds. Used in Java, Spring, and many enterprise schedulers.

Quartz cron uses 7 fields: Seconds Minutes Hours Day-of-month Month Day-of-week Year. Key differences: starts with seconds, supports L (last) and W (weekday) modifiers, uses ? for "no specific value". When migrating cron schedules between platforms, the most common issues are: (1) Quartz requires 7 fields starting with seconds, (2) AWS EventBridge needs a 6th year field and uses ? instead of * in conflicting day fields, (3) Kubernetes uses the standard 5-field format but adds features like concurrencyPolicy and successfulJobsHistoryLimit, (4) GitHub Actions may delay scheduled workflows during peak load periods. Always test your cron expression on the target platform before relying on it in production. When migrating cron schedules between platforms, the most common issues are: (1) Quartz requires 7 fields starting with seconds, (2) AWS EventBridge needs a 6th year field and uses ? instead of * in conflicting day fields, (3) Kubernetes uses the standard 5-field format but adds features like concurrencyPolicy and successfulJobsHistoryLimit, (4) GitHub Actions may delay scheduled workflows during peak load periods. Always test your cron expression on the target platform before relying on it in production.

FAQ

What does the cron expression 0 * * ? * * mean?
The expression 0 * * ? * * means: at minute 0, hour *, day-of-month *, month ?, day-of-week *. Each field in the cron expression controls a different time component: minute, hour, day of month, month, and day of week.
How do I add 0 * * ? * * to my crontab?
Run crontab -e in your terminal to open your crontab editor. Add a new line: 0 * * ? * * /path/to/your/script.sh. Save and exit. Verify with crontab -l. Make sure your script is executable (chmod +x script.sh) and uses full paths for all commands.
What is the equivalent of 0 * * ? * * on Quartz / AWS / Kubernetes?
Quartz Scheduler: 0 * * ? ?. AWS EventBridge: cron(0 * ? ? * *). Kubernetes CronJob: schedule: "0 * * ? * *" (standard 5-field format). Each platform has slight syntax differences — use our dialect switcher above to get the exact expression.
What are common mistakes when using 0 * * ? * *?
Common pitfalls: (1) Cron uses a minimal PATH — always use full paths to commands and scripts. (2) Percent signs (%) must be escaped with backslash in crontab. (3) Cron runs in the system timezone — set CRON_TZ=UTC at the top of your crontab for consistent UTC scheduling. (4) Redirect output to prevent email spam: 0 * * ? * * /path/command >> /var/log/myjob.log 2>&1. (5) Test your cron expression with crontab.guru or our validator above before deploying.

Platform Equivalents for 0 * * ? * *

The cron expression 0 * * ? * * has different syntax on various scheduling platforms. Here is the equivalent expression for each:

Platform	Expression
Unix / Linux crontab	`0 * * ? * *`
Quartz Scheduler (Java)	`0 * * ? ?`
AWS EventBridge	`cron(0 * ? ? * *)`
Kubernetes CronJob	`0 * * ? * *`
Vercel Cron	`0 * * ? * *`
GitHub Actions	`0 * * ? * *` (UTC)

Key differences across platforms: Quartz uses 7 fields starting with seconds and supports L (last) and W (weekday) modifiers. AWS EventBridge requires a 6th year field and uses ? instead of * in day fields when the other day field is specified. Kubernetes uses standard 5-field Unix cron. Vercel Cron uses the same format but schedules are defined in vercel.json. GitHub Actions uses standard cron but runs in UTC timezone only, so adjust the hour field for your local timezone offset.

Getting Started with Cron

Follow these tips when setting up cron jobs in production:

Always use full paths to commands and scripts in your crontab, since cron runs with a minimal PATH environment (often just /usr/bin:/bin).
Redirect output to log files: command >> /var/log/myjob.log 2>&1 to capture errors and prevent cron from emailing you every execution.
Test your cron expression before deploying — use our validator above or crontab.guru to verify the schedule fires when you expect.
Set MAILTO="" at the top of your crontab to disable email notifications, or set MAILTO=your@email.com to receive error alerts.
Use flock or a PID file to prevent overlapping executions for jobs that may take longer than their scheduled interval.