client receives an uevent.
Note that while you'll have access to all the device's properties and attributes for the majority of actions, only the sysfs path will be available when the device is removed.
Also note that the action is an arbitrary string, controlled by device drivers. Other values than those listed is possible, but unlikely.
This signal is emitted in the thread-default main loop of the thread that
client was created in.
The action for the uevent e.g. "add", "remove", "change", "move", "online" or "offline"
Details about the Device the event is for.