Cron Expression Builder
Build and validate cron expressions visually. See plain English descriptions instantly.
📅 At 02:00
Edit Fields
0-59, */5, 0,30
0-23, */6, 9,21
1-31, */2, 1,15
1-12, */3, 1-6
0-7 (0=Sun), 1-5
Usage
# Add to crontab
0 2 * * * /path/to/script.sh >> /var/log/cron.log 2>&1
Common Presets
What is a Cron Expression Builder?
Cron is the standard job scheduler for Unix-like operating systems, allowing you to automate tasks at specific times or intervals. A cron expression uses a five-field format representing minute, hour, day of month, month, and day of week. Each field accepts numbers, ranges, lists, and special characters like * (any value) and */ (step values). For example, */5 * * * * means every 5 minutes, while 0 2 * * 1 means every Monday at 2 AM.
This cron expression builder helps DevOps engineers, system administrators, and developers create and validate crontab schedules without memorizing the syntax. Common use cases include scheduling database backups, log rotation, certificate renewal, health checks, cleanup scripts, and deployment pipelines. Getting cron expressions right the first time saves debugging time and prevents missed or duplicate job executions that can cause production issues.
Frequently Asked Questions
How to run a cron job every 5 minutes?
Use the expression */5 * * * * to run a job every 5 minutes. The */5 in the minute field means "every 5th minute." This is one of the most common patterns used for health checks, metrics collection, and queue processing. You can verify it is working by checking /var/log/syslog or running crontab -l to list active jobs.
What does */5 mean in crontab?
The */ notation is a step value in cron syntax. */5 in the minute field means "every 5 minutes" (at minutes 0, 5, 10, 15, etc.). You can use step values in any field: */2 in the hour field means every 2 hours, and */3 in the day-of-month field means every 3 days. It is shorthand for writing out the full list of values.
How to check if cron is running?
On systemd-based systems, use systemctl status cron or systemctl status crond. You can also check the cron log with grep CRON /var/log/syslog on Debian/Ubuntu or /var/log/cron on RHEL/CentOS. To verify your specific job ran, add output redirection to a log file in your crontab entry: */5 * * * * /script.sh >> /var/log/myjob.log 2>&1.