What value do I pass to `xrandr --output`?

Question

I wish to add a new modeline using xrandr, however when I want to switch to the new modeline, I am asked to provide --output. The manual page doesn't explain where I can get my options from.

So how do I find out what value to pass to --output?

Answer 1

xrandr wants to know which output port you want to apply the new modeline to. Most modern graphics hardware supports more than one output port, for example an HDMI port plus a VGA port on a graphics hard or an internal LCD screen plus an external port on a laptop.

Run xrandr without any arguments to see a list of available outputs. The names of the outputs are usually of the form VGA1 or LVDS1. This will also tell you whether or not each output is connected and what its resolution and available modelines currently are.