How to change keyboard layout when usb keyboard connected

These are the steps to make linux switch between keyboard layouts when you connect an external USB keyboard

1. Create a script called switchKeyboard.sh that switches between the two layouts that you have

#!/bin/bash
# Get current index of keyboard layout
curKB=$(gsettings get org.gnome.desktop.input-sources current)
isExternalKBconnected=$(lsusb | grep Keyboard | wc -l)
newKB=-1
#If you have more keyboard layouts or in different order or their names are different you need to change this logic

if [[ "$curKB" = "uint32 1" && $isExternalKBconnected -eq 1 ]]; then 
  newKB=0
  newLY='latam'
fi 
if [[ "$curKB" = "uint32 0" && $isExternalKBconnected -eq 0 ]]; then 
  newKB=1
  newLY='us'
fi  
echo -----------------------
date
if [[ newKB -ne -1 && "uint32 ${newKB}" != $curKB ]]; then
    # Change Gnome keyboard layout
    gsettings set org.gnome.desktop.input-sources current $newKB

    echo loadkeys $newLY
    echo setxkbmap $newLY

    # Change the console and X keyboard layout
    sudo loadkeys $newLY
    sudo setxkbmap $newLY
else 
    echo current keyboard layout is kept
fi

# Show the current keyboard layouts and current keyboard index
gsettings get org.gnome.desktop.input-sources sources
gsettings get org.gnome.desktop.input-sources current

Note that running the above script will not reflect in the visual keyboard indicator on top, but if you type on any console or app you will notice the changes, also there is room for improvement to make it more generic and readable

2. Use python and pyudev to monitor usb devices getting connected/disconnected, and call the script of the first step every time the 'Keyboard' usb device changes between connected/disconnected call this script as keyboardDisConnected.py

#!/usr/bin/env python3

import pyudev
import subprocess

def main():
    context = pyudev.Context()
    monitor = pyudev.Monitor.from_netlink(context)
    monitor.filter_by(subsystem='usb')
    monitor.start()
    
    for device in iter(monitor.poll, None):

        dt = device.get('DEVTYPE')
        
        if (dt == 'usb_device'):
          # change this path to your home, using ~ does not work
          subprocess.call(['/home/mgg/switchKeyboard.sh'])  

if __name__ == '__main__':
    main()

3. run python keyboardDisConnected.py, connect and disconnect your usb keyboard you should see something similar to this:

4. Optionally run the python command as soon as the system starts

References:

• https://askubuntu.com/a/580428/94200
• https://unix.stackexchange.com/a/490555/244140