Reply To: THIS IS MY LAST HAIL MARY! Welcome Page › Forums › RetroPie Project › Controller Configuration in RetroPie › THIS IS MY LAST HAIL MARY! › Reply To: THIS IS MY LAST HAIL MARY! 03/04/2016 at 15:25 #119046 nosedeathParticipant At the prompt. ..to determine which /dev/input/mouse# device is being assigned, you can do cat /dev/input/mouse0 or cat /dev/input/mouse1 and see if characters appear when moving the trackball. Press ^C to stop.