Lubuntu 18.04 external HDMI display hotplug

90-monitor-hotplug.rules

ACTION=="change", ENV{DISPLAY}=":0", ENV{XAUTHORITY}="/home/USER/.Xauthority", RUN+="/bin/bash /home/USER/bin/monitorhotplug.sh"

README.md

Lubuntu 18.04 external display hotplug

When external HDMI display is connected, the internal display is automatically turned of. Suspending on lid close is turned off as well, so you can close laptop and continue to work.

When external display is disconnected, the internal display is turned back on, and suspending on lid close is restored as well.

Check if hotplug works

First of all make sure that plugging external display provides udev event.

Run udevadm monitor. You should see some events logged when you plug in and plug out external display.

If so, your machine is ready for hotplug config.

Create config

1. Create file /etc/udev/rules.d/90-monitor-hotplug.rules with content provided here.

Notice that <USER> should be substituted with actual user's name.

2. Create file ~/bin/monitorhotplug.sh with content provided here.
3. Make monitorplug.sh exectutable: chmod +x monitorplug.sh

monitorplug.sh

#!/bin/bash

# if a HDMI monitor is plugged in:
if [ $(cat /sys/class/drm/card0/card0-HDMI-A-1/status) = "connected" ]; then
    # set power settings
    # 1 for suspend, 0 for do nothing
    xfconf-query -c xfce4-power-manager -p /xfce4-power-manager/lid-action-on-ac -s 0

    # init xrandr, otherwise it won't work
    xrandr > /dev/null
    
    # turn on external screen and turn off laptop screen
    xrandr --output LVDS-1 --off
    xrandr --output HDMI-1 --auto

# in case of anything else reset to standard options
else
    # reset power settings
    xfconf-query -c xfce4-power-manager -p /xfce4-power-manager/lid-action-on-ac -s 1

    # init xrandr, otherwise it won't work
    xrandr > /dev/null

    # restore laptop screen and turn off external screen
    xrandr --output LVDS-1 --auto
    xrandr --output HDMI-1 --off
fi