What Databases are there under this Postgres???

Im new to Postgres, but Im in the process of reading the O'Reilly 'Practical PostgreSQL'.

I have a program here (that I am trying to understand) that uses Postgres, but its
getting errors. It would be 'nice' if I could look at the database and see if
(1) the records are not getting written.
(2) writing is ok, but there is a problem in the code trying to read them.
but I dont even know the NAME of the database that is being written (tht will take some
more digging in the code,- what Ive tried didnt work).

Is there some way (there must be) to get postgres to tell me what databases exist, owned by what users?
Knowing that data (there's only going to be my test databases and the one written by the
program) would save me a lot of time in debugging... The only listing I can get sofar just
shows the test databases I have built while reading the book.

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Reg.Clemens
reg(at)dwf(dot)com