[squarefoot]

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.

[CamouflagedKiwi]

And you could tell based on whether it ran at ~100FPS or several thousand. I assume that doesn't work so well any more...

[sitzkrieg]

it used to be slideshow vs 30fps on some cards back in the day

[Inhibit]

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").

[sgt]

Was it using xdpyinfo or driconf or something? Muscle memory tells me it's somewhere around there.