More flexible than the single configuration file is it to
configure libpam via the contents of the
/etc/pam.d/ directory. In this case the
directory is 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.
The syntax of each file in /etc/pam.d/ is similar to that of the
/etc/pam.conf file and is made up of lines
of the following form:
type control module-path module-arguments
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, /etc/pam.d/login contains the
configuration for the login service.