Reset linux system password

reset-password.py

import os
import sys
import base64
import crypt


def hash_passwd(passwd):
    # SHA-512
    return crypt.crypt(passwd, "$6$" + base64.b64encode(os.urandom(16)))

def update_userpasswd(username, password):

    with open('/etc/shadow', 'rb') as fd:
        shadow_rows = fd.readlines()

    found = False
    for index, row in enumerate(shadow_rows):
        if row.startswith(username):
            found = True
            cols = row.split(':')
            cols[1] = hash_passwd(password)
            shadow_rows[index] = ':'.join(cols)

    if found:
        with open('/etc/shadow', 'wb') as fd:
            fd.write(''.join(shadow_rows))
        return True

    return False

if __name__ == '__main__':
    if len(sys.argv) != 3:
        print "%s [username] [password]" % sys.argv[0]
        os._exit(1)

    if not update_userpasswd(sys.argv[1], sys.argv[2]):
        os._exit(2)