Using crontab on the Raspberry PI

Cron is described as a time-based job scheduler for the Raspberry PI and most Linux based OSes.

crontab is the tool to setup what is called a "cron job"...

crontab -e

• The -e is to edit the current users crontab. Use -l instead to list the current jobs.
• You could use sudo crontab -e to edit jobs for root.

The first time you use crontab it might ask you to select an editor. Just select your editor of choice. nano would be my preference on a RPI.

Add an entry at the bottom of the file similar to any one of the examples below...

The simplest; execute test.sh every minute...

* * * * * /home/pi/test.sh

Execute at every 15th minute interval. i.e 10:00, 10:15, 10:30: 10:45, and so on...

*/15 * * * * /home/pi/test.sh

Execute on the hour, every hour...

0 * * * * /home/pi/test.sh

Execute every minute on 1st May only...

* * 1 5 * /home/pi/test.sh

You can also setup a job to execute when the cron service restarts, usually at boot...

@reboot /home/pi/test.sh

Pi My Life Up's Beginners Guide to Cron Jobs and Crontab is a good guide. crontab guru is also a handy tool.

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