<para>

To determine the set of existing roles, examine the <structname>pg_roles</structname>

system catalog, for example

system catalog, for example:

<synopsis>

SELECT rolname FROM pg_roles;

</synopsis>

or to see just those capable of logging in:

<synopsis>

SELECT rolname FROM pg_roles WHERE rolcanlogin;

</synopsis>

The <xref linkend="app-psql"/> program's <literal>\du</literal> meta-command

is also useful for listing the existing roles.

</para>

<para>

In order to bootstrap the database system, a freshly initialized

system always contains one predefined role. This role is always

a <quote>superuser</quote>, and by default (unless altered when running

<command>initdb</command>) it will have the same name as the

operating system user that initialized the database

cluster. Customarily, this role will be named

system always contains one predefined login-capable role. This role

is always a <quote>superuser</quote>, and by default it will have

the same name as the operating system user that initialized the

database cluster, unless another name is specified while

running <command>initdb</command>.

It is common, but not required, to arrange for this role to be named

<literal>postgres</literal>. In order to create more roles you

first have to connect as this initial role.

</para>