Starting the database server

Hi all,

I try to start PostgreSQL, but it doesn't work. I installed it
successfully and now I try to launch the server. This is what I did:

1. Set the path
    $ set path = ( /usr/local/pgsql/bin $path )

2. Create the cluster
    $ initdb -D /usr/local/pgsql/data

3. Start the database server
    $ postmaster -D /usr/local/pgsql/data

It's in the last part when I try to start the database server that I
get this error message:

FATAL: no such group 'pgsql'
postmaster: cannot create UNIX stream port

I don't understand why? For doing all these steps I was logged as
postgres admin. I installed PostgreSQL 7.2.2 on Mac OSX 10.2.

Can someone help me to understand what was my mistake?

Thanks a lot
Javier