newbie question

[Daniel J. Luke]

On May 3, 2011, at 9:27 PM, Tena Sakai wrote:
> 
> When I try what you mention ("psql -U postgres postgres")
> here's what happens:
>    $ /opt/local/lib/postgresql90/bin/psql -U postgres postgres
>    Password for user postgres: 
>    psql: FATAL:  password authentication failed for user "postgres"

that's because you supplied an incorrect password for the postgres user.

> I gave "trust" as you suggested.

nope, I suggested that the default authentication method (as set in your pg_hba.conf file) was 'trust' authentication which does not require a password.

> Clearly the account postgres exists.  (Because I can su to it
> from being root.)  

you are confusing a system level postgres account with a database postgres account/user

> But on this incarnation of the OS (snow
> leopard, 10.6.7), one is supposed to manage password
> changes via Accounts (in System Preferences).  And
> according to Accounts, there is no such user as postgres.
> Curiously, it does show the group postgres.

the Accounts pane in system preferences doesn't show all system accounts.

> I have looked at the passwd file via vipw and postgres doesn't
> exist in it.  So, where is the account postgres?

on Mac OS X, system accounts (and passwords) are not stored in the passwd file.

> Here's something else kinda strange:
>    $ echo ~postgres
>    /Applications/postgres
>    $ ls -ld /Applications/postgres
>    ls: /Applications/postgres: No such file or directory

that doesn't really matter (although it probably means your postgres user wasn't created by macports, as the postgres90-server port creates the postgres user with a $HOME of ${prefix}/var/db/postgresql90)

> At this point, I went back to Accounts (via System Preferences)
> and looked at group postgres.  And I saw my account is shown
> in membership panel and there is a box for check mark next to
> it, which was unchecked.  I checked it and got out of the Accounts
> and rerun psql command as before:
>    $ psql -U postgres postgres
>    psql (9.0.4)
>    Type "help" for help.
> 
>    postgres=# \q
> 
> Bingo!  it doesn't ask password anymore!

you probably have a ~/.pgpass with the password you set for the postgres user saved in it (and the permissions on the file were probably set for the postgres group).

> Now I can go ahead to create database of my choice and populate
> tables, it seems.

You really should read through the postgres documentation as it does seem like you don't understand how postgres client authentication works.

http://www.postgresql.org/docs/9.0/interactive/client-authentication.html

--
Daniel J. Luke                                                                   
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