dual screens, xrandr: get names of video devices

Question

I have been trying to configure dual-screen with my laptop docking station using xrandr.

After some Google and SU searches, I have managed to:

xrandr --output LVDS --pos 1680x0

Which sets my laptop screen (LVDS) to be just at the right size of my desktop screen.

Now, if I like to put it on the left side, I must use this notation:

xrandr --output LVDS --left-of MY_DESKTOP_SCREEN

Of course, there's no MY_DESKTOP_SCREEN device so I get:

xrandr: cannot find output "MY_DESKTOP_SCREEN"

How do I find or configure the names of my video devices?

Answer 1

This site helped, so i typed:

xrandr -q

q stands for query, which gives:

Screen 0: minimum 320 x 200, current 1680 x 1050, maximum 2960 x 1050
VGA connected 1680x1050+0+0 (normal left inverted right x axis y axis) 474mm x 296mm
   1680x1050      60.0*+   59.9
   1280x1024      75.0     59.9
   1280x960       59.9
   1152x864       75.0     74.8
   1024x768       75.1     70.1     60.0
   832x624        74.6
   800x600        72.2     75.0     60.3     56.2
   640x480        75.0     72.8     66.7     60.0
   720x400        70.1
LVDS connected 1280x800+0+0 (normal left inverted right x axis y axis) 331mm x 207mm
   1280x800       60.2*+   60.0     50.0
   1280x768       60.0
   1024x768       60.0
   800x600        60.3
   640x480        59.9
TV disconnected (normal left inverted right x axis y axis)

Now I can:

xrandr --output LVDS --left-of VGA

And: