noip update with up-to-date check in a shell script

update.sh

#!/usr/bin/env bash

# set env variables or directly here
NOIPDOMAIN=<your domain>
NOIPUSER=<your noip update username>
NOIPPASS=<your noip password>



CURRENT_IP=$(dig +short $NOIPDOMAIN | tail -n1)
MY_IP=$(dig @resolver4.opendns.com myip.opendns.com +short)

if [[ "$CURRENT_IP" == "$MY_IP" ]]

    then
        echo "redirect is up to date, pointing to $MY_IP"
    else
        echo "updating redirect from ip $CURRENT_IP to ip $MY_IP"
        curl https://$NOIPUSER:[email protected]/nic/update?hostname=$NOIPDOMAIN&myip=$MY_ID
fi

After some more debugging & googling, it was probably not the fritz box, but noip.com. I recommend Free DNS now. Very simple setup, but just works!