Help automate pg_dump

We just upgraded from 7.1.3 to 7.2.1 and are at a loss on how to
script the pg_dump routine. We use this tool for backup, but can not
get around the requirement for username/password to be interactive.

We require login from the localhost, and can not revert to trusted
connections.

If the username/password must be interactive, how can I script backup
of the server?

Evan,