user passwords

why is it that I can sign in to the postgres database using PSQL without
having to specify a password for a user even thought one has been specified
in pg_shadow?

I signed in to Linux with my own personal id (which is NOT a postgres
account) and used the following command to get in:

psql -U postgres dbname

It let me in to our database as postgres (a superuser account) without even
prompting for a password.

Am I missing something?
thanks
Jodi
_______________________________________________________________ Jodi L
Kanter BioInformatics Database Administrator University of Virginia (804)
924-2846 jkanter@virginia.edu