Running v8.1 amd v8.2 at the same time for a transition

Hi all.
I need to run both 8.1 and 8.2 at the same time in order to check
everything in 8.2 *before* shutting 8.1 down.
I need to run both as I only have one machine available.
I'm using a debian derivateive (Kubuntu) that provides a nice pg_wrapper
mechanism to direct connections for tools to either version you want.
Infact I see both versions running, one on port 5432 and one on port 5433.
The point is thay I have no clue on ow to choose which instance attach to.
I've already posted this question to the KUbuntu team with no answer in 14+
hours.

Is there anyone with a good hint?

Thanks.

--
Vincenzo Romano
--
Maybe Computer will never become as intelligent as Humans.
For sure they won't ever become so stupid. [VR-1988]