Send messages to the system logger
#include <syslog.h>
#include <security/pam_ext.h>
void pam_syslog(pam_handle_t *pamh, int priority, const char *fmt, ...); void pam_vsyslog(pam_handle_t *pamh, int priority, const char *fmt, va_list args);
The pam_syslog function logs messages using syslog(3) and is intended for internal use by Linux-PAM and PAM service modules. The priority argument is formed by ORing the facility and the level values as documented in the syslog(3) manual page.
The pam_vsyslog function performs the same task as pam_syslog() with the difference that it takes a set of arguments which have been obtained using the stdarg(3) variable argument list macros.
pam(7)
The pam_syslog and pam_vsyslog functions are Linux-PAM extensions.