Looks good, unfortunately doesn’t work on Debian10, but it’s because of the regex,… Location is lowercase for me here, so the correct string ist for me:
curl -sI https://latest.mattermost.com/mattermost-team-linux | sed -n 's!^location.*/\([0-9]\+\)\.\([0-9]\+\)\.\([0-9]\+\)/mattermost-.*!\1\2\3!p'
Thanks so far! I can monitor now updates much better 