This is a little yet useful bash script that shows notifications when any USB device is plugged/unplugged.

Honestly, I don't quite understand why this essential feature is not implemented in major Linux distributions by default. There are notifications about removable storage, but not much more than that: e.g. no notifications about usb-to-com converters, etc. I really want to know when my devices get recognized by the system, or disconnected for whatever reason (be it a bad USB cable connection, or whatever).