Application calls to the PAM framework search for the configured PAM services in the following order:
The service name is looked up in the /etc/pam.conf file.
Specific services are used in the /etc/pam.d/service-name file.
The service name other is checked in the /etc/pam.conf file.
The /etc/pam.d/other file is used.
This order enables an existing /etc/pam.conf file to work with the per-service PAM configuration files in the /etc/pam.d directory.