Code Technicalities.

A PAM module's source code should include <security/pam_module.h>. In order to use some of the functions, it must define certain macros before including this file - these will be shown where appropriate.

The module's source file should be compiled as a shared library, in the following way:

gcc -fPIC -c a_pam_module.c
gcc -Wl,x -shared -o a_pam_module.so a_pam_module.o -lpam