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Chani
Asked: 2013-06-30 23:20:48 +0800 CST

How to turn on the VGA display without using the function keys

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It is a well documented issue about some of the function keys not working on laptops. I am having the same issue with my Display Function key i.e. the key that is used to switch to turn on the VGA output.

My question is, if we cannot get the function key to work, what is a way to do the task manually ?

For some background to this question, please see this.

display

1 Answers

  1. You could use the command line tool xrandr to do that.

    Query you monitors with xrandr -q, which should give you an output like:

    > xrandr -q
Screen 0: minimum 320 x 200, current 1024 x 600, maximum 4096 x 4096
LVDS1 connected 1024x600+0+0 (normal left inverted right x axis y axis) 220mm x 129mm
   1024x600       60.0*+   65.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA1 connected (normal left inverted right x axis y axis)
   1280x1024      75.0 +   60.0  
   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

    The two lines

    LVDS1 connected 1024x600+0+1024 (normal left inverted right x axis y axis) 220mm x 129mm
VGA1 connected (normal left inverted right x axis y axis)

    are the connected monitors, where LVDS1 is the internal laptop screen, and VGA1 the one connected with the VGA-cable. You can also see that the laptop screen currently uses a resolution of 1024x600. The VGA screen is not used yet.

    Below that are the possible configuration for the monitor. The one marked with an asterisk '*', is the active one.

    LVDS1 connected 1024x600+0+0 (normal left inverted right x axis y axis) 220mm x 129mm
   1024x600       60.0*+   65.0

    You can turn both on with (mirrored setup/ both display the same)

    xrandr --output LVDS1 --auto --output VGA1 --auto

    If you want an extended desktop use something like

    xrandr --output LVDS1 --auto --output VGA1 --above LVDS1

    Now the VGA screen is 'above' the laptop screen. If you want to extend your desktop into another direction use one of

    • --left-of
    • --right-of
    • --above
    • --below

    Now the query output looks like:

    Screen 0: minimum 320 x 200, current 1280 x 1624, maximum 4096 x 4096
LVDS1 connected 1024x600+0+1024 (normal left inverted right x axis y axis) 220mm x 129mm
   1024x600       60.0*+   65.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA1 connected 1280x1024+0+0 (normal left inverted right x axis y axis) 340mm x 270mm
   1280x1024      75.0*+   60.0  
   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

    The part after the resolution 1024x600+0+1024 of the VGA1 is the position the screens have in relation to each other. It means VGA1 has the resolution 1024x600, is 0 pixel right of VGA1, and 1024 pixel under it.

    To turn one screen of use the --off switch:

    xrandr --output LVDS1 --off
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