Related to this question. But my concern is that over the past year, most of my more interesting (or used) applications are from PPAs, and just backing up my sources list won't add the associated launchpad keys the way that add-apt-repository does.

So I'm looking for a way to list all the PPA urls (like ppa:chromium-daily/stable) so that I can easily script a series of add-apt-repository commands to add them into a new installation gracefully.

Short of dumping my bash history of course. Which might be feasible, depending on how far back that file goes back?