user account management

I want to give a postgres account for each user of my linux server.
In my idea, users would be able to connect without auth in console mode with psql.
In addition they could connect to their base througth php scripts and manage their DB
with phpPgAdmin. In this case, they will give their linux user name and password to auth.
The admin will also be able to log in all dbases and manage them all.

I can do all of this in trust mode, but that allows my user to log on everybody account
and that is not really secure.

With the following conf, I have the authentification in console mode ok, but I can't use
neither phpPgAdmin (can't login) or just connect with a simple php script.

Could somebody help me to configure the pg server ? (I have RTFM chapter 6 and browse the forum, but I'm still in a mess with pguser accounts) Also I want to do this conf into conf files

Thanx a lot for your help

pg_hba.conf (without trust)
----------------------------

host sameuser 127.0.0.1 255.255.255.255 ident sameuser
host sameuser 10.0.0.0 255.255.255.255 ident sameuser
local sameuser ident sameuser

pg_ident.conf : empty
--------------

postgresql.conf :
-----------------

tcpip_socket = true

max_connections = 32

port = 5432
hostname_lookup = false
show_source_port = false

unix_socket_directory = ''
unix_socket_group = ''
unix_socket_permissions = 0777