$ xrandr
Screen 0: minimum 3840 x 1200, current 3840 x 1200, maximum 3840 x 1200
default connected 3840x1200+0+0 0mm x 0mm
   3840x1200      50.0* 
$ xrandr --output "Screen 0" --left-of default
warning: output Screen 0 not found; ignoring