Update script for dynamic dns.

update.sh

#! /bin/bash

MYIP=$(wget -qO - http://myexternalip.com/raw)
USER=Redacted
PASSWORD=Redacted
HOST=Redacted

if [ ! -f /var/run/last.ip ]
	then echo $MYIP > /var/run/last.ip
	curl -s -X GET "https://nic.ChangeIP.com/nic/update?u=$USER&p=$PASSWORD&myip=$MYIP&hostname=$HOST&set=1"
fi

if ! cmp -s /var/run/last.ip <(echo $MYIP)
	then  curl -s -X GET "https://nic.ChangeIP.com/nic/update?u=$USER&p=$PASSWORD&myip=$MYIP&hostname=$HOST&set=1"
	echo $MYIP > /var/run/last.ip
fi

sleep 30s

NEWIP=$(dig $HOST | tail -n 9 | grep $HOST | cut -f5)

if [ "$MYIP" != "$NEWIP" ]
	then rm /var/run/last.ip
fi

exit 0