chgpasswd: -s flag is only allowed with the -c flag
Usage: chgpasswd [options]

Options:
  -c, --crypt-method METHOD     the crypt method (one of NONE DES MD5 SHA256 SHA512)
  -e, --encrypted               supplied passwords are encrypted
  -h, --help                    display this help message and exit
  -m, --md5                     encrypt the clear text password using
                                the MD5 algorithm
  -R, --root CHROOT_DIR         directory to chroot into
  -s, --sha-rounds              number of SHA rounds for the SHA*
                                crypt algorithms

