(OS X) Watch a URL and display a Notification Center notification when the URL has changed

urlwatch

#!/bin/bash

if [ -z "$1" ] ; then
   echo "Supply a URL to watch."
   exit 1
fi 

tempfile1=`mktemp -t urlwatch`
tempfile2=`mktemp -t urlwatch`

curl "$1" > $tempfile2
cat $tempfile2
cp $tempfile2 $tempfile1
echo
echo ---
while diff -q $tempfile1 $tempfile2 ; do
    curl -s "$1" > $tempfile1
    sleep 5
done
echo
cat $tempfile1

osascript -e "display notification \"URL $1 changed.\""