How to install PostgreSQL 9.1 on OSX Lion - osx-lion

Question

I downloaded PostgreSQL from the official website and ran the .dmg installer. After that I downloaded pgadmin3 and I am indeed able to connect to the database.
when I run 'psql' I get the following error:
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
After hours of googling I read about some $PATH issues, so I put this into my .bashrc:
export PATH=/Library/PostgreSQL/9.1/bin:$PATH
However, this doesn't solve the error above at all. After some more hours of googling I tried to run 'psql -l localhost -U postgres'. This gives another error:
psql: could not connect to server: Connection refused
Is the server running on host "localhost" (::1) and accepting
TCP/IP connections on port 5432?
could not connect to server: Connection refused
Is the server running on host "localhost" (127.0.0.1) and accepting
TCP/IP connections on port 5432?
could not connect to server: Connection refused
Is the server running on host "localhost" (fe80::1) and accepting
TCP/IP connections on port 5432?
After some more googling I tried to edit /Library/PostgreSQL/9.1/data/pg_hba.conf and replaced all occurrences of 'md5' with 'trust'.
Then I changed user to postgres and executed 'pg_ctl stop' and 'pg_ctl start', switched back to my own user and tried to connect again, no luck.
Here are some more infos:
[~]$ which psql
/Library/PostgreSQL/9.1/bin/psql
ps aux | grep postgres
postgres 19022 0.0 0.0 2446096 484 ?? Ss 11:31PM 0:00.01 postgres: stats collector process
postgres 19021 0.0 0.0 2486532 1776 ?? Ss 11:31PM 0:00.01 postgres: autovacuum launcher process
postgres 19020 0.0 0.0 2486400 576 ?? Ss 11:31PM 0:00.03 postgres: wal writer process
postgres 19019 0.0 0.0 2486400 820 ?? Ss 11:31PM 0:00.05 postgres: writer process
postgres 19017 0.0 0.0 2446096 356 ?? Ss 11:31PM 0:00.01 postgres: logger process
postgres 19015 0.0 0.1 2486400 8216 s001 S 11:31PM 0:00.17 /Library/PostgreSQL/9.1/bin/postgres
sudo find / -name .s.PGSQL.5432
No file was found?!?
Update 1:
In /etc/sysctl.conf I added the values suggested by the installer's README:
kern.sysv.shmmax=1610612736
kern.sysv.shmall=393216
kern.sysv.shmmin=1
kern.sysv.shmmni=32
kern.sysv.shmseg=8
kern.maxprocperuid=512
Before these settings, the installer quits with an error, afterwards the wizard appears and installs postgres (and again, using pgadmin3 works, so I assume that the database is running fine).

Answer 1

Run lsof on the master process to all of this. In your case it's 19015 (shown with my PID):
> sudo lsof -p 286 | awk '$5 == "unix" && $NF ~ /\// { print $NF }'
/tmp/.s.PGSQL.5432
You can leave off the awk, but basically it's getting the UNIX socket on which postgres is listening. From there, you can use the -h option to psql (but only include the directory).
> psql -h /tmp template1
template1=# \q
If that doesn't work, you can check the lsof output to show you what TCP port it's actually listening on, and if it's not 5432, use the -p option to postgres

Answer 2

If you are able to connect to the database through pgadmin3, then your database is running.
(1) I'd verify by running netstat -an | grep 5432 on the command line, as a paranoia check. You are in business i.e. you actually installed Postgresql if you get this below:
tcp4 0 0 *.5432 . LISTEN
tcp6 0 0 *.5432 . LISTEN
ffffff80133bfed8 stream 0 0 ffffff8013be8000 0 0 0 /tmp/.s.PGSQL.5432
(2) Speaking for myself, I found that just running psql gets me your psql error message. I had to run
psql -h 127.0.0.1 -p 5432 [-d database] -U postgres
to connect with the database. In other words, I had to explicitly specify IP and port. Since you were able to run psql and get a non-connect error message, the OS understands that psql is a command and you don't have a pathing issue.