Automatically scan and print dev list when USB device added or removed.

usb-rescan-print.sh

#!/bin/bash

###############################################################################
# Author:        Alex Hogen <[email protected]>
#                https://github.com/ahogen
# Date Created:  2018-07-19
#
# Copyright (c) 2018, Alexander Hogen.
#
# Usage:
#
#     This is a simple, stupid script I whipped up because I really wanted a
#     simple USB device monitor which informed me when a USB device was added
#     or removed.
#
#     Built with Linux Mint 18.3 (Ubuntu 16.04) and lsusb (usbutils) 007.
#
# MIT License:
#
# Permission is hereby granted, free of charge, to any person obtaining a copy 
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights 
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
# copies of the Software, and to permit persons to whom the Software is 
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE
###############################################################################

# Get current list (as a string)
devListLast=$(lsusb)
printf "${devListLast}\n"

# Check every second for device changes. If there is a change, print the new
# device list. It's up to the user to figure out which one was added/removed.
while true; do

    devListNow=$(lsusb)

    if [ "$devListLast" != "$devListNow" ]; then
        printf "===============================================\n"
        # Would be nice to show a diff instead. I haven't had to do that
        # before and wasn't sure how, so I decided not to.
        #diff "${devListLast}" "${devListNow}"
        printf "${devListNow}\n"
        
        devListLast=${devListNow}
    fi
    
    sleep 1
done