SQL errors

 ~   master ⭑  postgres                                         09:48:24 PM
postgres does not know where to find the server configuration file.
You must specify the --config-file or -D invocation option or set the PGDATA environment variable.
 ~   master ⭑  psql                                       ➶ 2  09:48:27 PM
psql: FATAL:  role "mona" does not exist
 ~   master ⭑  psql -U postgres                           ➶ 2  09:50:56 PM
psql (9.3.2)
Type "help" for help.

postgres=# \du
                             List of roles
 Role name |                   Attributes                   | Member of
-----------+------------------------------------------------+-----------
 postgres  | Superuser, Create role, Create DB, Replication | {}

postgres=#