GLXGears was my command of choice to verify if my graphics drivers were installed. Either they would run smoothly (when installed) or choppy and broken. Can’t use that anymore because the APUs and generic drivers got so good that everything runs smoothly. Good times.
Yes, I recall using GLXInfo in a xterm window to check whether I correctly installed graphics drivers or not. "Direct Rendering: Yes" would confirm that. Good old times indeed.
That'll still work to see which driver is running. Might want to append "| head -30" so you don't get all the unnecessary debug for your answer, though. Or grep for what you're expecting (i.e. "| grep -i nvidia").
