pam_close_session man page
pam_close_session — terminate PAM session management
int pam_close_session(pam_handle_t *pamh, int flags);
The pam_close_session function is used to indicate that an authenticated session has ended. The session should have been created with a call to pam_open_session(3).
It should be noted that the effective uid, geteuid(2). of the application should be of sufficient privilege to perform such tasks as unmounting the user's home directory for example.
The flags argument is the binary or of zero or more of the following values:
Do not emit any messages.
Memory buffer error.
Session was successful terminated.
pam(3), pam_filter(8), pam_open_session(3), pam_setcred(3), pam_sm_close_session(3).