Usually my laptop is connected to an external monitor and when I’m programming I normally use two screens. But when I’m doing something else like watching a video or playing a game I just need one monitor, the external one.

So we will write a little script to toggle the built-in monitor on and off.

The command we will use is xrandr which (quoting man xrandr) “is used to set the size, orientation and/or reflection of the outputs for a screen. It can also set the screen size.”

I found this guide in the ArchWiki that explains how to do a similar thing, toggling the external monitor. So I took that and slightly changhed it to my use case.

Here’s the final script:

#!/bin/sh

if ! xrandr --listmonitors | grep HDMI; then
	return 0
fi

if xrandr --listmonitors | grep eDP; then
	xrandr --output eDP --off
else
	xrandr --output eDP --auto --left-of HDMI-A-0
fi

In the first part we use xrandr --listmonitors to get the list of connected monitors. The output for me is like this:

❯ xrandr --listmonitors
Monitors: 2
 0: +*HDMI-A-0 1920/477x1080/268+1920+0  HDMI-A-0
 1: +eDP 1920/344x1080/193+0+0  eDP

So we can check if the external monitor is connected using grep.

If xrandr --listmonitors | grep HDMI is false we exit the script since there is nothing to do (the external monitor is not connected).

Then we use the same method to check if the built-in monitor (named eDP on my machine) is on. If it is we can turn it off with:

xrandr --output eDP --off

Instead if it’s off we need to turn it on. We can also specify its position relative to the other monitor:

xrandr --output eDP --auto --left-of HDMI-A-0

So in my case I put it --left-of my external monitor.

Finally we can save the script to a file, let’s call it monitor, make it executable (chmod u+x monitor) and put it to a location in our path (like $HOME/bin) so we can run it easily from the terminal.