Notify if a page changes

notify_page_changes.sh

#!/usr/bin/env sh
# This script notifies when a page changes.
# The first argument is the url, the other is a command that will notify you,
# like 'growlnotify -s -p 2 -t "Title" -m "Message"' if you use Growl.
#
# Example:
# $ notify_page_changes.sh 'http://reddit.com' 'growlnotify -s -p 2 -t "Reddit.com" -m "Changed"'
#
# IMPORTANT: remember to put your arguments in quotation marks!

INTERVAL=15
URL="$1"
NOTIFICATION="$2"
FILES=("/tmp/npc_$$_old.html" "/tmp/npc_$$_new.html")
LOGFILE="/tmp/npc_$$.log"

function download () {
  curl -L -o ${FILES[1]} $URL &> $LOGFILE
  if [ $? != 0 ]
      then cat $LOGFILE
      exit $?
  fi
}

function old_is_equal_to_new () {
  mv ${FILES[1]} ${FILES[0]}
  download
  diff -u ${FILES[0]} ${FILES[1]}
  return $?
}

function clean () {
    rm ${FILES[0]} ${FILES[1]} $LOGFILE
    exit 0
}

trap clean INT

download

while old_is_equal_to_new; do
  sleep $INTERVAL
done

eval $NOTIFICATION

clean