  Chapter 7. Database Users and Permissions  Table of Contents
7.1. Database Users 7.2. Groups 7.3. Privileges 7.4. Functions
and Triggers  Managing database users and their privileges is in
concept similar to that of Unix operating systems, but then
again not identical enough to not warrant explanation.  7.1.
Database Users   name follows the rules for SQL identifiers:
either unadorned without special characters, or double-quoted.
To remove an existing user, use the analog DROP USER command.
For convenience, the shell scripts createuser and dropuser are
wrappers around these SQL commands.  In order to bootstrap the
database system, a freshly initialized system always contains
one predefined user. This user will have the same name as the
operating system user that initialized the area (and is
presumably being used as the user that runs the server). Thus,
often an initial user "postgres" exists. In order to create more
users you have to first connect as this initial user.   7.1.1.
User attributes     database