Dual monitor settings in Ubuntu are clumsy at best. I have tried set ups on numerous machines and I find the most reliable method is to change the monitors.xml file. For more information on monitors.xml, check out the Ubuntu Wiki on Resolutions.
First of all lets open up a terminal:
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Ctrl + Alt + T |
Now lets navigate to the folder where monitors.xml is stored:
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cd ~/.config |
You need to open the file in a text editor, we’ll use Ubuntu’s native editor, gedit:
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gedit monitors.xml |
Choosing your primary monitor
You will have something like the text below. There is only 2 words that you will have to change in the file, possibly 3. (the <……..> is for display purposes only, you will have a few more lines of content in there)
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<monitors version=“1”> <configuration> <clone>no</clone> <output name=“DVI-0”> <........> <primary>yes</primary> </output> <output name=“DIN”> </output> <output name=“DVI-1”> <........> <primary>no</primary> </output> </configuration> </monitors> |
- First make sure that the clone tag says “no” – <clone>no</clone>. if you don’t have this line, create it on the third line.
- Next, make sure the <primary>yes</primary> is on the correct output. If it isn’t change it, but make sure you change the other to “no” as above.
Now restart your computer or restart X and it will load up with the correct monitor settings.
NOTE – This will only take effect after you have logged in. LightDM has its own monitor settings (that I will be posting soon).
Setting monitor positions
Monitors.xml also specifies the position of your monitors.
The <x> and <y> values determine the position. They are based on the distance from the top left corner of the screen and are measured in pixels.
This set up includes a 22 inch monitor on the left, and 17 inch monitor on the right.
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<monitors version=“1”> <configuration> <clone>no</clone> <output name=“DVI-0”> <vendor>MAX</vendor> <product>0x089a</product> <serial>0x00000b3e</serial> <width>1680</width> <height>1050</height> <rate>60</rate> <x>0</x> <y>0</y> <rotation>normal</rotation> <reflect_x>no</reflect_x> <reflect_y>no</reflect_y> <primary>yes</primary> </output> <output name=“DIN”> </output> <output name=“DVI-1”> <vendor>HWP</vendor> <product>0x264b</product> <serial>0x01010101</serial> <width>1280</width> <height>1024</height> <rate>0</rate> <x>1680</x> <y>0</y> <rotation>normal</rotation> <reflect_x>no</reflect_x> <reflect_y>no</reflect_y> <primary>no</primary> </output> </configuration> </monitors> |
As you can see above, the first output device (or monitor!) has an <x> value of 0 (<x> is the horizontal position). The second output has an <x> value of 1680, which is equal to the <width> of the first output. This positions the secondary monitor 1680 pixels from the left – on the seam of the first monitor.
If you have some height differences in the position of your monitor you would need to edit the <y> value of the appropriate monitor.
As with any changes to this file, you will need to restart your computer or restart X to make these corrections apply. They will take effect after you have logged in as LightDM has its own monitor settings (coming soon).
Change dual monitor resolutions
You can see a complete version of the monitors.xml above, but the only part needed here is this:
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<width>1680</width> <height>1050</height> |
These 2 lines set the resolution for the output devices (your dual monitors!). Set them appropriately for each of your devices. Sometimes your proprietary graphics drivers/software will fail to modify this file causing some conflicts. You should change this to match any settings you are specifying elsewhere.
Remember to restart your computer or restart X to make these corrections apply.