How to Create and Set Up a Cron Job in Ubuntu

Create a cron job

Step 1: Open the crontab editor

crontab -e

The first time, Ubuntu asks which editor to use. Choose nano (the easiest).

Step 2: Add a job

Use this format:

* * * * * command_to_execute

The five stars are minute, hour, day of month, month and day of week.

Example, run a backup script every day at 2:00:

0 2 * * * /home/user/scripts/backup.sh

Step 3: Save and exit

In nano press Ctrl+O, Enter, then Ctrl+X. Cron reads the new file by itself.

Example: write a message every minute

* * * * * echo "This is a message written every minute" >> /home/user/message.txt

Wait a few minutes, then read the file:

cat /home/user/message.txt

Remove the job when the test is done, or it will keep running.

Check your cron jobs

crontab -l

More tips

• Use full paths for commands and scripts.
• Make scripts executable: chmod +x script.sh.
• Send the output to a log to find errors: ... >> /var/log/myjob.log 2>&1.
• Check that the service runs: systemctl status cron.
• See what ran: grep CRON /var/log/syslog.
• Use sudo crontab -e for jobs that need root.

Quick recap

• crontab -e to add jobs, crontab -l to list them.