dbus_signal_test.py

import dbus
from dbus.mainloop.glib import DBusGMainLoop
from gi.repository import GLib

DBusGMainLoop(set_as_default=True)

def device_added(object_path):
    print("Device Added")
    print(object_path)
    print(type(object_path))

def device_removed(object_path):
    print("Device Removed")
    print(object_path)
    print(type(object_path))

  
bus = dbus.SystemBus()
obj = bus.get_object("org.freedesktop.NetworkManager","/org/freedesktop/NetworkManager")

interf = dbus.Interface(obj,"org.freedesktop.NetworkManager")
interf.connect_to_signal("DeviceAdded", device_added)
interf.connect_to_signal("DeviceRemoved", device_removed)

loop = GLib.MainLoop()
loop.run()