cron

Learn how to schedule and automate tasks in Linux using cron jobs.

Commands

Common commands for checking, editing and managing cron jobs.

Check cron service

Ensure that the cron service is installed and running.

systemctl status cron

Edit user crontab

Open the crontab editor for the current user.

crontab -e

List scheduled jobs

View existing cron jobs for the current user.

crontab -l

Remove all jobs

Clear the user’s crontab.

crontab -r

Automate with system-wide crontab

System jobs can be placed in /etc/crontab

sudo nano /etc/crontab

Syntax

Cron jobs use a five-field time format followed by the command to execute.

# ┌───────────── minute (0–59)
# │ ┌───────────── hour (0–23)
# │ │ ┌───────────── day of month (1–31)
# │ │ │ ┌───────────── month (1–12)
# │ │ │ │ ┌───────────── day of week (0–6, Sun=0)
# │ │ │ │ │
# │ │ │ │ │
# * * * * * command_to_execute

Examples

Common examples of scheduling tasks with cron.

Run script every day at midnight

0 0 * * * /home/username/backup.sh

Run a task every 15 minutes

*/15 * * * * /usr/bin/python3 /home/username/task.py

Weekly cleanup task

0 3 * * 0 root /usr/bin/apt autoremove -y