Thread: Linux Users vs PostgreSQL Users

On Tuesday, November 10, 2015 10:41:35 AM Michael Convey wrote:
> ​Are PostgreSQL roles always associated with a Linux user account? In other
> words, can I have a PostgresSQL user account that is unrelated to any Linux
> account? Is there a detailed tutorial on accounts and roles that explains
> this topic? I found the following confusing:
>
> http://www.postgresql.org/docs/9.3/static/client-authentication.html
> http://www.postgresql.org/docs/9.3/static/user-manag.html
> http://www.postgresql.org/docs/9.3/static/database-roles.html

PostgreSQL roles are created and maintained separately from system accounts.

It is possible to setup PostgreSQL in such a way that it can share
authentication information with identically-named systems accounts, but is not
normally setup that way.

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.

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.
Sorry for that.

On Tuesday, November 10, 2015 05:45:51 PM you wrote:
> ​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

The second postgres tells psql which database to connect to. There is by
default one named postgres. And yes it is redundant in this case, as I believe
psql tries to connect to a database named after the user you connect as, if
you don't otherwise specify the database name.

So in this case you have a system user called postgres, a PostgreSQL role
called postgres, and a default database called postgres, all coming into play,
which is probably a little confusing at first.

      Dear Fellow U.S. Citizen,

      As described in the letter below, this December, President Obama is
planning to make the U.S. a state of a global government and is taking
executive action to redistribute what we earn and own to all developing
countries worldwide.

      To keep this from happening, take action as soon as possible!

      ·         Please, read the letter below to understand what Obama and
the U.N. are plotting to do against us and what your Senators and
Representatives can do to stop him.

      ·         Forward this email unchanged to everyone you know or
otherwise can contact.

      ·         On http://www.house.gov/, enter you zip code and press Go,
or on http://www.house.gov/representatives/, click the first letter of your
state, then click on the link (their name) to your Representative's website.
Navigate to your Representative's contact page. Copy and paste the letter
below into your Representative's contact page, and send it to your
Representative.

      ·         On http://www.senate.gov/senators/contact/, choose your
state, and click the link to your Senator's website's contact page or
website. Copy and paste the letter below into your Senator's contact page,
and send it to your Senator.

      Your future depends on you. Make taking those steps a high priority.
Thank you.

      Here is the text of the letter .



      SUBJECT: Last Chance to Defend Our Freedom - Impeach and Imprison
Obama

      Being a U.S. citizen, it is my civic duty and honor to write to you
regarding a matter of grave national consequences.

      This December, at the 21st meeting of the U.N. Framework Convention on
Climate Change (UN FCCC) Conference of the Parties (COP-21) in Paris,
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a state of a global government; the UN FCCC COP. This global government will
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Third, charge former President Obama with one count of capital theft for
each U.S. citizen whose hard-earned income has already been stolen to fund
green energy, cooperative R&D, and other projects in foreign countries and
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rejecting any legally-binding agreement with the UN FCCC, impeaching
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