root@ylspirit:~# xrandr
Screen 0: minimum 320 x 200, current 2880 x 900, maximum 8192 x 8192
LVDS2 connected 1440x900+1440+0 (normal left inverted right x axis y axis) 304mm x 190mm
   1440x900       60.2*+   59.9     50.0  
   1360x768       59.8     60.0  
   1152x864       60.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA2 connected 1440x900+0+0 (normal left inverted right x axis y axis) 408mm x 255mm
   1440x900       59.9*+   75.0  
   1280x1024      75.0     60.0  
   1280x800       59.8  
   1152x864       75.0  
   1024x768       75.1     70.1     60.0  
   832x624        74.6  
   800x600        72.2     75.0     60.3     56.2  
   640x480        72.8     75.0     66.7     60.0  
   720x400        70.1  
DP1 disconnected (normal left inverted right x axis y axis)

root@ylspirit:~# xrandr --output VGA2 --auto --left-of LVDS2

关闭外接显示器 ：

root@ylspirit:~# xrandr --output VGA2 --off

关闭本本显示器：

root@ylspirit:~# xrandr --output LVDS2 --off

再次开启双屏幕：

root@ylspirit:~# xrandr --output VGA2 --auto --left-of LVDS2

其他，参数

root@ylspirit:~# xrandr -h
usage: xrandr [options]
  where options are:
  -display <display> or -d <display>
  -help
  -o <normal,inverted,left,right,0,1,2,3>
            or --orientation <normal,inverted,left,right,0,1,2,3>
  -q        or --query
  -s <size>/<width>x<height> or --size <size>/<width>x<height>
  -r <rate> or --rate <rate> or --refresh <rate>
  -v        or --version
  -x        (reflect in x)
  -y        (reflect in y)
  --screen <screen>
  --verbose
  --current
  --dryrun
  --nograb
  --prop or --properties
  --fb <width>x<height>
  --fbmm <width>x<height>
  --dpi <dpi>/<output>
  --output <output>
      --auto
      --mode <mode>
      --preferred
      --pos <x>x<y>
      --rate <rate> or --refresh <rate>
      --reflect normal,x,y,xy
      --rotate normal,inverted,left,right
      --left-of <output>
      --right-of <output>
      --above <output>
      --below <output>
      --same-as <output>
      --set <property> <value>
      --scale <x>x<y>
      --transform <a>,<b>,<c>,<d>,<e>,<f>,<g>,<h>,<i>
      --off
      --crtc <crtc>
      --panning <w>x<h>[+<x>+<y>[/<track:w>x<h>+<x>+<y>[/<border:l>/<t>/<r>/<b>]]]
      --gamma <r>:<g>:<b>
      --primary
  --noprimary
  --newmode <name> <clock MHz>
            <hdisp> <hsync-start> <hsync-end> <htotal>
            <vdisp> <vsync-start> <vsync-end> <vtotal>
            [+HSync] [-HSync] [+VSync] [-VSync]
  --rmmode <name>
  --addmode <output> <name>
  --delmode <output> <name>