<section xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="pam.conf-dir">
    <para>
      More flexible than the single configuration file is it to
      configure libpam via the contents of
      <filename>pam.d</filename> directories. In this case the
      directories are filled with files each of which has a filename
      equal to a service-name (in lower-case): it is the personal
      configuration file for the named service.
    </para>

    <para>
      Vendor-supplied PAM configuration files might be installed in
      the system directory <filename>/usr/lib/pam.d/</filename> or
      a configurable vendor specific directory instead
      of the machine configuration directory <filename>/etc/pam.d/</filename>.
      If no machine configuration file is found, the vendor-supplied file
      is used. All files in <filename>/etc/pam.d/</filename> override
      files with the same name in other directories.
    </para>

    <para>
      The syntax of each file in pam.d is similar to that of the
      <filename>/etc/pam.conf</filename> file and is made up of lines
      of the following form:
    </para>

    <programlisting>
type  control  module-path  module-arguments
    </programlisting>

    <para>
      The only difference being that the service-name is not present. The
      service-name is of course the name of the given configuration file.
      For example, <filename>/etc/pam.d/login</filename> contains the
      configuration for the <emphasis remap="B">login</emphasis> service.
    </para>
</section>
