After upgrading to Lion, I get the following error when trying to start up the Postgres server:
pg_ctl: could not open PID file "/usr/local/var/postgres/postmaster.pid": Permission denied
I also tried to re-run the initdb command, but ran into a similar problem:
initdb: could not access directory "/usr/local/var/postgres": Permission denied
If it matters, PostgreSQL was installed via Homebrew. Running brew info postgresql yields the expected results (version, summarized docs).
Well, it turns out the solution was pretty simple. I changed the group on /usr/local/var to staff (from wheel) and changed the ownership (chown -R) to my system account (from root).
After that, postgres started up fine.
I was a little nervous changing those permissions, but the only thing in my /usr/local/var was a postgres directory, so all should be well. If you have other directories/files in /usr/local/var, maybe don't use the -R flag when chown'ing?
The Homebrew ruby installer script changes the group of /usr/local/var to staff, so that must have gotten undone when upgrading to Lion. Not sure about the ownership being root instead of my system account though...
来源：https://stackoverflow.com/questions/6834118/postgresql-permissions-issue-after-upgrading-to-os-x-lion