Script should be placed under `/etc/NetworkManager/dispatcher.d/` with a name like `99-disable-wireless-when-wired`. Make sure 1) root owns it 2) it's mod is 755

99-disable-wireless-when-wired

#!/bin/sh

IFACE=$1
ACTION=$2

ntfy () {
	sudo -u cengiz \
		DISPLAY=:0 \
		DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus \
		notify-send "$1" "$2"
}

case ${IFACE} in
	eth*|usb*|en*)
		case ${ACTION} in
			up)
				ntfy "Ethernet connected" "Disabling Wifi"
				nmcli radio wifi off
				;;
			down)
				ntfy "Ethernet disconnected" "Enabling Wifi"
				nmcli radio wifi on
				;;
		esac
		;;
esac