我最近在 Kubuntu 16.04.1 LTS 下切换了显卡，xrandr 命令已缓存了许多旧设置。
$ xrandr | grep "connected"
DVI-D-0 disconnected (normal left inverted right x axis y axis)
HDMI-0 connected 2560x1600+0+0 (normal left inverted right x axis y axis) 641mm x 401mm
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 connected primary 2560x1600+2560+0 (normal left inverted right x axis y axis) 641mm x 401mm
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis) …