This will make it possible to log in as
<systemitem class="username">jack
</systemitem> and use the
<citerefentry><refentrytitle>su
</refentrytitle><manvolnum>1
</manvolnum></citerefentry> command to become
<systemitem class="username">root
</systemitem>. Then you will not get scolded any more for logging in as
<systemitem class="username">root
</systemitem>.