How to get a notify-send notification if a bluetooth device connects

We'll be using udev for this, first off we'll start by writing the scripts we want to run when the bluetooth device connects/disconnects. We'll save these scripts in /bin/. As I only have a bluetooth headphone my shell scripts look like this:
runuser -l USER -c 'notify-send "Headphone connected 🎧"'

runuser -l USER -c 'notify-send "Headphone disconnected 🎧"'

Where you change USER to your username (e.g for me arthur). This is needed as there's a complication of getting into the x session from root, you don't need to worry about that. I already tried a lot of stuff and this works.

We now wish to run this as a bluetooth device gets connected, for this we'll have to create a udev rule. We do this by creating a file in /etc/udev/rules.d/ We can call this whatever we want, but it needs to have the ".rules" extension. For example I created the file BluetoothHeadphone.rules This file looks as follows:

SUBSYSTEM=="bluetooth", ACTION=="add", RUN+="/bin/"
SUBSYSTEM=="bluetooth", ACTION=="remove", RUN+="/bin/"

And then we're done! Now we only have to reload udev:

sudo udevadm control --reload
back button home button