Finding current PHP sessions

Hello all, I guess this comes up once in a while, does anybody know how I can find the current PHP sessions' IDs? I don't mind if some have passed away, and the PHP gc hasn't run yet, because I'm doing a garbage collection of my own, for data identified by session ID -- it doesn't really matter if I keep a few obsolete files for a while, it only matters that I delete them at some point in the future. I know I could read the session files themselves, but I'd very much rather use a "proper" way to retrieve the active sessions, which would work with alternate methods of storing session data, if there is any such proper way to do this. I read the PHP documentation regarding sessions, and I checked out Google, with no luck. If you guys don't have a solution, it means that there is none -- in other words, you're my last hope, help! :-) Cheers, Bogdan