Edit the script, fill out the first four variables. Chmod the file, so you could run it: chmod +x update.sh Test it: ./update.sh If it's working you could install it as a cronjob, mine runs every 12 hours, but you should know how much downtime you can acceppt.
Original script from https://uk.godaddy.com/community/Managing-Domains/Dynamic-DNS-Updates/td-p/7862 , but it uses an old api, that is nor working from 2020/03/30.