Developer Tools

Crontab
Generator

Q: What does */15 mean in cron?

A step value. */15 in the minute field runs the job every 15 minutes. Likewise */2 in the hour field runs every 2 hours.

Q: How do I edit my crontab?

Run crontab -e to edit your user crontab and crontab -l to list it. Paste the generated line on its own row followed by the command to run.

Build cron schedules visually and copy a ready-to-paste crontab line. Get a plain-English read-out so you always know when it runs.

5-field cron

Human readable

Quick presets

# min hour dom mon dow
0 3 * * * /backup.sh # daily 3am
*/15 * * * * ping.sh # every 15m
0 0 * * 0 rotate.sh # weekly
@reboot startup.sh # on boot

Frequently Asked Questions

How do I read a cron expression?

The five fields are, in order: minute (0–59), hour (0–23), day of month (1–31), month (1–12) and day of week (0–6, where 0 is Sunday). An asterisk * means "every".

What does */15 mean in cron?

A step value. */15 in the minute field runs the job every 15 minutes. Likewise */2 in the hour field runs every 2 hours.

How do I edit my crontab?

Run crontab -e to edit your user crontab and crontab -l to list it. Paste the generated line on its own row followed by the command to run.

What is @reboot?

A special schedule that runs the job once each time the server boots, instead of on a clock schedule. Other shortcuts include @daily, @hourly and @weekly.