This guide was written for Steam OS 2.0 Brewmaster
In order to follow these guides, you will first need to perform a bit of setup to be able to access the files we need to modify. You will also need a USB keyboard attached to your Steam Machine to be able to enter the necessary commands. will need to do this with superuser permissions. If you have not yet configured your Steam Machine to give you desktop access, follow this guide. Once you have, log in and open the terminal by mousing over Activities, and typing terminal into the search box. Once it is open, you will need to create a password for your superuser account. Do that by using the following commands.
It will then prompt you to create a password. This will be your root password for all future password prompts in the Terminal.