use python passlib to generate sha512-crypt on osx with optional rounds

sha512-crypt

#!/usr/bin/env python

# pip install passlib

import getpass
import random
import string
import argparse

from passlib.hash import sha512_crypt

parser = argparse.ArgumentParser()
parser.add_argument('--rounds', type=int, default=5000, help='specify the rounds')
args = parser.parse_args()

print sha512_crypt.using(salt=''.join([random.choice(string.ascii_letters + string.digits) for _ in range(16)]),
                         rounds=args.rounds).hash(getpass.getpass())