password        [success=2 default=ignore]      pam_unix.so obscure sha512

password        [success=2 default=ignore]      pam_unix.so obscure sha512 minlen=4

password    [success=1 default=ignore]  pam_unix.so obscure sha512

password    [success=1 default=ignore]  pam_unix.so obscure sha512 minlen=4

password    [success=1 default=ignore]  pam_unix.so minlen=2 sha512