Getting started with Cron jobs

Kenny Chou · June 26, 2025

Tutorial   Cron

So you want to set up a Cron Job on your linux machine? If you ask Google, all you’ll get is “Open crontab -e” and add 0 0 * * 0 /path/to/your/command

But what if the job you want to run is slightly more complicated? This post is intended to be a quick guide, for the lazy (like myself) who don’t want to read the Cron Guide in its entirety.

Let’s get started!

1. Create a script for the job you want to run, we’ll call it with cron: touch /path/to/your/script.sh
2. Make your script executable: sudo chmod +X /path/to/your/script.sh
3. Run sudo crontab -e to edit your Cron job file.

4. Set up a test job – add the following to the end of the Cron file: * * * * * su - <user.name> -c 'cd /home/<user.name>/ && /path/to/your/script.sh' >> /tmp/script-output.log 2>&1

   Explanation: * * * * * runs your job every minute, and >> /tmp/script-output.log 2>&1 logs the output cronjob runs as root by default, and will not have access to your configs and settings. su - <user.name> runs the cronjob as the user you specify.

5. Cron runs in an isolated environment with very little access to the tools you’ve installed. In your script.sh, you need to give cron the tools it needs for code execution:

    # Give it access to PATHs
    HOME="<your profile's home directory>"
    export PATH="$HOME/.local/bin:/usr/local/bin:/usr/bin:/bin:$PATH"
   
    # Set environment variables so cron has access to tools and configs. For example:
    export GH_CONFIG_DIR="$HOME/.config/gh"
    source $HOME/.bashrc
   
    # add some information for logging purposes
    current_datetime=$(date +%Y-%m-%dT%H:%M:%S)
    echo "current time is {$current_datetime}"
   
    # You can call a complicated set of commands with a Makefile target - e.g., build and deploy a container.
    make test_cronjob
   

6. Examine the log to check whether your job is successful: sudo cat /tmp/script-output.log
7. Once your test job is successful, edit your Cron file or scripts to call the actual job you want to run.
8. Update the job execution frequency from * * * * * to something more reasonable, like 0 0 * * 0 (every Sunday at midnight).

Hope that saved you a few minutes of Googling.