“add-apt-repository” is an Ubuntu-specific script to add or remove repositories which, among others, automatically imports the public GPG key. For more information, see its man page.
You can use “add-apt-repository” in Debian to add Launchpad PPAs however, there are a few things that you should know. Read on to find out how to use “add-apt-repository” in Debian.
Full article here:
How To Add Launchpad PPAs In Debian Via `add-apt-repository` Command (Web Upd8)