This utility is used to periodically check to see if the external IP address has changed, and if so, send a notification giving the new IP address.

ip_check

#!/bin/bash

# This utility is used to periodically check to see if the external IP address
# has changed, and if so, send a notification giving the new IP address.
#
# Reasons why crontab does not work - http://askubuntu.com/questions/23009/reasons-why-crontab-does-not-work

FLAG=0                          # set to 1 for verbose output
MYPATH="/home/jeff/bin"         # path to apprise, need for running in cron

# Parse command line options
USAGE="Usage: `basename $0` [-h] [-x]"
while getopts hx OPT; do
    case "$OPT" in
        h)
            echo $USAGE
            exit 0
            ;;
        x)
            FLAG=1
            ;;
        \?)
            # getopts issues an error message
            echo $USAGE >&2
            exit 1
            ;;
    esac
done

# get current and old IP address
IP_ADDRESS_STORE=$HOME/.external_ip_address
CURRENT_IP=$(cat $IP_ADDRESS_STORE)
NEW_IP=$(curl --silent ifconfig.co)

# send message about any changes
if [ $CURRENT_IP == $NEW_IP ];
    then
        if [ $FLAG -eq 1 ];
            then
                $MYPATH/apprise -t "External IP Address" -m "No change in home router external IP address ($CURRENT_IP)."
        fi
        exit 2
    else
        echo $NEW_IP > $IP_ADDRESS_STORE
        $MYPATH/apprise -t "External IP Address" -m "Your home router external IP address has changed from $CURRENT_IP to $NEW_IP."
        exit 3
fi