pam_setcred sets the module-specific credentials of the user. It is usually called after the user has been authenticated, after the account management function has been called and after a session has been opened for the user.
flags maybe specified from among the following values:
set credentials for the authentication service
delete credentials associated with the authentication service
reinitialize the user credentials
extend lifetime of the user credentials
Additionally, the value of flags may be logically OR'd with PAM_SILENT.
Module cannot retrieve the user's credentials.
User's credentials have expired.
User is not known to an authentication module.
Module was unable to set the credentials of the user.