Cron Generator

Generate cron expressions with an easy visual builder. Select minutes, hours, days, months, and weekdays to create cron schedules for automated tasks.

Cron Expression

0 9 * * *

At 09:00 every day

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About Cron Expressions

Cron is a time-based job scheduler in Unix-like operating systems. It enables users to schedule jobs (commands or scripts) to run automatically at specified times and dates. The cron expression format uses five fields separated by spaces, allowing you to precisely control when a job executes. Cron is essential for automating maintenance tasks, backups, data processing, and reporting.

Common Cron Use Cases

  • System Backups: Schedule daily/weekly backups during low-usage hours
  • Log Rotation: Automatically rotate and compress log files
  • Data Sync: Synchronize data between systems at regular intervals
  • Report Generation: Generate and email reports on a schedule
  • Cache Clearing: Clear application caches during off-peak hours
  • Health Checks: Run periodic system monitoring scripts

Frequently Asked Questions

What is a cron expression?
A cron expression is a string of 5 fields separated by spaces that defines a schedule: minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-7, where 0 and 7 = Sunday). Each field can contain specific values, ranges (1-5), lists (1,3,5), step values (*/15), or wildcards (*). For example, `0 9 * * 1-5` means 'every weekday at 9:00 AM'.
How do I run a cron job every 30 minutes?
Use the expression `*/30 * * * *`. The `*/30` in the minute field means 'every 30 minutes'. This runs at :00 and :30 of every hour, every day. For every 10 minutes use `*/10 * * * *`, and for every 2 hours use `0 */2 * * *`.
What is the difference between cron and crontab?
Cron is the system daemon that executes scheduled jobs on Linux/Unix systems. Crontab (cron table) is the file that contains the schedule of cron entries. Each user has their own crontab file. The format is the same: minute/hour/day/month/weekday command. You edit crontab entries using the `crontab -e` command.
How do I schedule a job for specific weekdays?
Use the day-of-week field (5th position). Values: 0 or 7 = Sunday, 1 = Monday, 2 = Tuesday, 3 = Wednesday, 4 = Thursday, 5 = Friday, 6 = Saturday. For weekdays only use `1-5` (Monday to Friday). For weekends use `0,6` (Saturday and Sunday). Combine with specific times like `0 9 * * 1-5` for weekdays at 9 AM.
What does */5 in a cron field mean?
The `*/5` syntax means 'every 5' of that unit. In the minute field, `*/5` means every 5 minutes (at :00, :05, :10, etc.). In the hour field, `*/2` means every 2 hours. In the day-of-month field, `*/3` means every 3 days. This is called a 'step value' and is one of the most useful cron expression features.
Can I set a cron job for specific months only?
Yes, the month field (4th position) accepts values 1-12 or three-letter abbreviations (JAN, FEB, etc.). For example, `0 0 1 1,4,7,10 *` runs at midnight on the 1st of January, April, July, and October (quarterly). Use ranges like `6-8` for summer months only (June through August).

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