Re: Linux Users vs PostgreSQL Users

On Tue, Nov 10, 2015 at 10:59 AM, Felipe Santos <felipepts(at)gmail(dot)com> wrote:

> AFAIK there isn´t such a thing.
>
> You are free to create users/roles/groups in Postgres without a match in
> the Linux system.
>
> They are completely separate things, and you would only end up with the
> same OS users and DB users if you intended to do so by naming them equally,
> but still they are different kinds of objects, like cars and fruits.
>
> For convenience and security, the POSTGRES OS user is usually created in
> the installation process and is related to the POSTGRES DB user by the
> configuration set in PG_HBA.CONF
>

​On Tuesday, November 10, 2015 12:24:14 PM Alan Hodgson wrote:

> It is common, though, that distributions will setup PostgreSQL in such a way
> that it automatically trusts connections from identically named systems
> accounts via the Trust authentication method. You can change that in
> pg_hba.conf.

That should be the "ident" authentication method. "trust" trusts any account.

​Thanks Alan & Felipe. So, in the following line, what does the last
"postgres" do and is it necessary?

sudo -u postgres psql postgres

Source: 1st answer at
http://serverfault.com/questions/110154/whats-the-default-superuser-username-password-for-postgres-after-a-new-install

Wouldn't this be the same?

sudo -u postgres psql