Making xrandr modifications permanent with lightdm

README.md

Overview

xrandr is the easiest way to make a multiple display configuration work in Linux. Lightdm is my current display manager. This file explains how to make lightdm run an arbritrary script (in this case an xrandr script) on startup.

Here's the command we need:

#!/usr/bin/env bash
xrandr --output DVI-0 --mode 1920x1080 --left-of VGA-0

Obviously you can modify that to fit your specific setup. Any valid command works here.

sudo cat > /usr/share/multiple-monitors.sh << EOF
#!/usr/bin/env bash
xrandr --output DVI-0 --mode 1920x1080 --left-of VGA-0
EOF
sudo chmod +x /usr/share/multiple-monitors.sh

Open up /etc/lightdm/lightdm.conf and change the following line from:

#display-setup-script = 

To:

display-setup-script=/usr/share/multiple-monitors.sh

Restart everything as appropriate. Check in /var/log/lightdm/lightdm.log for errors.

Note: Make the change under the [Seat] section in /etc/lightdm/lightdm.conf

This solution really works, but it is important to clarify that the display-setup-script parameter to modify must be under the section [Seat:*], otherwise it will not work.

Thank you! This works great for me.