Fedora Linux

I was trying to get my Sony DualSense controller to work ingame and managed to google my way to a solution (I think).

The controller works fine in Steam fullscreen mode, but refuses to pass the signals on to the game?

I found this, and started following the instructions and everything went well until I came to point 5.

What does it mean to "put 'X' into 'Y' file"? How do I do this? Which commands do I need to input in my console? is 'uinput' a separate file that I missed to download or do I just need to append the text "uinput" to the file somehow?