Monitors external IP address using curlmyip.com and sends an email when it changes (should be run from cron)

ip-monitor.sh

#!/bin/bash

FILE="$HOME/ip-monitor.txt"
OLD_IP=`cat $FILE`
CURRENT_IP=`curl -s http://curlmyip.com`
EMAILS="[email protected]"
SUBJECT="IP address changed"
FROM="IP Address Bot <root@localhost>"

if [ "$CURRENT_IP" ]; then
  if [ "$CURRENT_IP" != "$OLD_IP" ]; then
    echo "New external IP address: $CURRENT_IP" | mail -s "$SUBJECT" -a "From: $FROM" $EMAILS
    echo "$CURRENT_IP" > $FILE
  fi
fi