since
<application>createuser</application> will automatically prompt
for a password if the server demands password authentication.
However, <application>createuser</application> will waste a
connection attempt finding out that the server wants a password.
In some cases it is worth typing <option>-W</option> to avoid the extra
connection attempt.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1>
<title>Environment</title>
<variablelist>
<varlistentry>
<term><envar>PGHOST</envar></term>
<term><envar>PGPORT</envar></term>
<term><envar>PGUSER</envar></term>
<listitem>
<para>
Default connection parameters
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><envar>PG_COLOR</envar></term>
<listitem>
<para>
Specifies whether to use color in diagnostic messages. Possible values
are <literal>always</literal>, <literal>auto</literal> and
<literal>never</literal>.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
This utility, like most other <productname>PostgreSQL</productname> utilities,
also uses the environment variables supported by <application>libpq</application>
(see <xref linkend="libpq-envars"/>).
</para>
</refsect1>
<refsect1>
<title>Diagnostics</title>
<para>
In case of difficulty, see <xref linkend="sql-createrole"/>
and <xref linkend="app-psql"/> for
discussions of potential problems and error messages.
The database server must be running at the
targeted host. Also, any default connection settings and environment
variables used by the <application>libpq</application> front-end
library will apply.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
To create a user <literal>joe</literal> on the default database
server:
<screen>
<prompt>$ </prompt><userinput>createuser joe</userinput>
</screen>