Postgresql : psql: FATAL: IDENT authentication failed for user "postgres"

So what I have is a postgreSQL database and I was trying to connect to
it via a Python module (PyGreSQL) from the same machine. I created a
table under the user 'postgres' called postgres.

When I started up the machine and logged on, I was the root. When I
tried to do this:

psql -U postgres -d postgres

I got:

psql: FATAL: IDENT authentication failed for user "postgres"

so I figured out I had to switch user and be postgres instead of root
with:

su postgres

then, after issuing the same command:

psql -U postgres -d postgres

I had success.

By the way, the same goes if you're trying to access a table via a
Python module. If the database (or table) is for a certain user, you
must be logged in as that user before you can access it with pg or
pgdb.

Hope that helps someone...