I just upgraded my postgresql server from 8.4 to 9.2 on ubuntu linux 12.04. I installed the new version then used pg_upgrade to upgrade and replicate the cluster from the old server to the new.
Everything appears to have worked well except that I am left with a problem with my pg_hba.conf file. For some strange reason it only accepts a single line. So by default I had just:
local all postgres ident
All attempts to add any additional lines to this file, such as