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Since I found a different method to achieve my goal, and since no answer was posted to my previous question, I've changed the question to match the answer I found.

Is there a way to turn off my laptop's monitor and turn on the external monitor(and vice-versa) entirely from the command line?

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I was just googling for the exact same thing and I stumbled on this question which you asked only 7 minutes ago. That's friggin amazing. I do hope you get an answer. – JD Long Jun 21 '10 at 14:13
    
I know that you can drop a basic xorg.conf into the root (/root/yorg.conf.new) directory, if you boot into recovery mode and execute X --configure (or similar). – Bobby Jun 21 '10 at 14:24
    
the problem (at least for me) is that I don't want to write out an xorg.conf by hand. I want to dump my current settings into xorg.conf format then change settings with the GUI and then dump those into a file. Then I can write a script to change between the two settings really easy. Right now I have to go into the GUI and click half a dozen times to change my settings. – JD Long Jun 21 '10 at 14:42
    
@JD Long: That is exactly what I'm trying to do as well. Make sure to write here if you ever find a way. The only two things missing for my script are the xorg.conf files, and a command to refresh the current displays (without having to do gdm restart). – Malabarba Jun 21 '10 at 15:18
    
I've been experimenting with disper today (willem.engen.nl/projects/disper). The help file shows a -p option which is supposed to export. Only that switch is not implemented. sad trombone – JD Long Jun 21 '10 at 16:44
up vote 13 down vote accepted

With the commands

xrandr --output VGA-0 --auto
xrandr --output LVDS --off 

The screen automatically transfers to the external display. It doesn't even need sudo powers. To find out the name of the displays just do:

xrandr -q

Which should give something like:

VGA-0 connected 1280x1024+0+0 (normal left inverted right x axis y axis) 338mm x 270mm
...
LVDS connected (normal left inverted right x axis y axis)
...

Extending the displays can probably be achieved in a similar manner.

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I get the message "Can't open display" when running xrandr (with any flags). What can be the reason? – brandizzi Apr 30 '13 at 12:17
    
Worked great, thanks! – canotto90 Jun 12 '15 at 3:34

This is most certainly NOT a direct answer to your question. But I found it helpful in my use case. This is not an export of the config file, but it does show how to automate disper in a shell script. I'm setting this up to run every time I dock/un-dock and it seems to be fixing my display issues when docking and undocking my laptop:

You have to have disper and Python installed.

#!/bin/sh
#
# Detect displays and move panels to the primary display
#

PYTHON=python2.6
DISPER=/usr/bin/disper

# disper command will detect and configure monitors
$PYTHON $DISPER --displays=auto -e -t left

# parse output from disper tool how many displays we have attached
# disper prints 2 lines per displer
lines=`$PYTHON $DISPER -l|wc -l`

display_count=$((lines / 2))

echo $display_count

echo "Detected display count:" $display_count

# Make sure that we move panels to the correct display based
# on the display count
if [ $display_count = 1 ] ; then
    echo "Moving panels to the internal LCD display"
    gconftool-2 \
    --set "/apps/panel/toplevels/bottom_panel_screen0/monitor" \
    --type integer "0"
    gconftool-2 \
    --set "/apps/panel/toplevels/top_panel_screen0/monitor" \
    --type integer "0"
    sleep 5
    pkill gnome-panel
else
    echo "Moving panels to the external display"
    gconftool-2 \
    --set "/apps/panel/toplevels/top_panel_screen0/monitor" \
    --type integer "1"
    gconftool-2 \
    --set "/apps/panel/toplevels/bottom_panel_screen0/monitor" \
    --type integer "1"
    sleep 5
    pkill gnome-panel
fi
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Disper seems like a useful tool. I'll look into it and see if I can make it fit my case. The only difference is that I want to disable the laptop's monitor, instead of extending it. It's a little smoother on my low-end laptop, and it deals with the panels automatically. – Malabarba Jun 21 '10 at 18:53
    
On second thought, my ati video card might not be supported, as they only claim to support nvidia. – Malabarba Jun 21 '10 at 18:54
    
Ok, the diper page led me to this page: thinkwiki.org/wiki/Sample_Fn-F7_script Turns out it's pretty easy to switch monitors with the xrandr command. – Malabarba Jun 21 '10 at 19:17
    
thanks for posting the xrandr link. I'll investigate that. I'm bumbling around with the same stuff. FWIW, my laptop has an Intel card and I'm using disper with no problems. – JD Long Jun 21 '10 at 19:32

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