Python use same argument several times keep as string

Question

I'm new to python and trying to figure out how to make this code accept multiple of the same argument -ex. I tried make it a action='append' but that gives me a error saying it need to be a string not a list. right now when using -ex several times it just uses the last instance of it example. python3 scrunch.py --no-rep -ex 123 -ex 456 5 5 abcdefg123456 output 12345 the output still contains 123.

import string
import argparse
import itertools
from math import factorial



def number_permutations(n, k):
 return factorial(n)/factorial(n-k)

def main():
    parser = argparse.ArgumentParser(description='Generate password combinations from charset'
    'with length in range: [MIN..MAX]. '
    'If any of -u, -l, -d, -hex option is set, then charset is ignored, but still must be provided.')

    parser = argparse.ArgumentParser(epilog="Example 1: "
    'python3 scrunch.py --no-rep -ex ABC 3 5 ABCDEFGH123456 '
    'Example 2: '
    'python3 scrunch.py --no-rep -f wordlist.txt -u -l -d 6 6 DUMMYCHARSET')

    parser.add_argument('-f', metavar='file', help='output text file name. Prints to STDOUT by default')
    parser.add_argument('-u', action='store_true', help='Use all uppercase characters. Overrides charset')
    parser.add_argument('-l', action='store_true', help='Use all lowercase characters. Overrides charset')
    parser.add_argument('-d', action='store_true', help='Use all decimal numbers. Overrides charset')
    parser.add_argument('-hex', action='store_true', help='Use all hex numbers. Overrides charset')
    parser.add_argument('-ex', help='Exclude char sequence')
    parser.add_argument('--no-digit-start', action='store_true', help='Do not start with digit')
    parser.add_argument('minlen', metavar='MIN', type=int,
                        help='Min length of combination')
    parser.add_argument('maxlen', metavar='MAX', type=int,
                        help='Max length of combination')
    parser.add_argument('charset', nargs=1)
    parser.add_argument('--no-rep', action='store_true', help='Any symbol can occur only once.')

    args = parser.parse_args()
    print (args.ex)
    a = ''.join(args.charset)
    b = ''
    if args.u:
     b += string.ascii_uppercase
    if args.l:
     b += string.ascii_lowercase
    if args.hex:
     b += string.hexdigits
    if args.d:
     b += string.digits

    if b:
      a = b

    s = sorted(a)
    print ("Sorted charset: {}".format(s))
    num = 0
    # Calculate number of possible combinations
    for L in range(args.minlen, args.maxlen + 1):
     num += number_permutations(len(s), L)
    print ("Number of permutations: %d" % num)

    if args.f:
     f = open(args.f, 'w')

    for L in range(args.minlen, args.maxlen + 1):
     if args.no_digit_start and args.no_rep:
      gen = permutations_no_digit_start(s, L)
     elif args.no_rep:
      gen = itertools.permutations(s, L)
     else:
      gen  = itertools.product(s, repeat=L)
     for x in gen:
      y = ''.join(x)
      if args.ex and args.ex in y:
       continue
      if args.no_digit_start and y[0].isdigit():
       continue
      if args.f:
       f.write("%s\n" % ''.join(x))
      else:
       print (''.join(x))

main()

Answer 1

1. replace line

   parser.add_argument('-ex', help='Exclude char sequence')
   

   to

   parser.add_argument('-ex', action='append', help='Exclude char sequence')
   

2. replace if check

   if args.ex and args.ex in y:
     continue
   

   to

   bad_pattern = False
   for ex in args.ex:
     if ex and ex in y:
       bad_pattern = True
       break
   if bad_pattern:
     continue
   

Explanation: by default only last value of -ex used. And that is 456. But action='append' allows to set list of values. And every usage of -ex will append new value to list. After that you have to check every value in args.ex list by iterating for ex in args.ex