On your Chromebook, Linux is off by default. You can turn it on any time from Settings.

1. On your Chromebook, at the bottom right, select the time.
2. Select Settings   >   Advanced  Developers.
3. Next to "Linux development environment," select Turn On.
4. Follow the on-screen instructions. Setup can take 10 minutes or more. Make sure to read carefully.
5. A terminal window opens. You have a Debian 11 (Bullseye) environment. You can run Linux commands, install more tools using the rooted sudo apt package manager, and customize your shell. 
6. Change your directory (Next page)