watch changes under /dev directory in linux.

udev_watcher

#!/usr/bin/bash

# will be ls /dev
# 2 files to compare before and 
# after plug in/out the device
before="/tmp/before.txt" 
after="/tmp/after.txt"


ls --color /dev > $before && clear

echo "############################"
echo "# Welcome to udev watcher! #"
echo "############################"
echo "1. Insert/remove device"
echo "2. Press any key to continue"
read -n 1 -r -s
clear && echo "Scanning..." && sleep 2

ls --color /dev > $after
result=$(diff $before $after)

clear && echo ""
if [ "$result" = "" ]; then
    echo "Not found any device changes"
else
    if [[ $result == *">"* ]]; then
        echo "New devices added:"
    else
        echo "Devices removed:"
    fi
    echo $result
fi

# CLEAN
rm -f $before $after