Watch for a file change

watch.sh

#!/bin/bash
# Will check for remote file change. Be aware, it downloads the file.
# (Made at first to execute a php script to notify when a file was updated)
# USAGE: `./watch.sh "http://exemple.com/file"`

curl -s -o "temp-dl" "$1"
firsthash="$(md5sum 'temp-dl')"
counttime="0"

while :
do
        sleep 120
        
        curl -s -o "temp-dl" "$1"
        newhash="$(md5sum 'temp-dl')"
        
        if [ "$firsthash" != "$newhash" ]
        then
                #curl -s "http://[...]"
                echo "FILE UPDATED"
                
                rm temp-dl
                break
        fi
        
        counttime=$(( $counttime + 2 ))
        #echo $counttime
done