Python simple string incrementer

string_incrementer.py

# -*- coding: utf-8 -*-
"""
Created on Fri May  8 00:07:46 2020

@author: ToishY

My favorite online string increment tool "was" dead (http://www.mynikko.com/tools/tool_incrementstr.html), so I made this snippet back then.
Haven't tested it fully but seems to work.

Note:
If there's double quotes in the string, just use a text editor to convert them 
to single quotes before passing them to the string incrementor

"""

import sys, getopt, re, datetime

def call_main(argv):
    user_string = ''
    placeholder = ''
    start = 0
    stop = 0
    padding = 0
    save_file = 'N'
    try:
        opts, args = getopt.getopt(argv,"hi:p:s:e:z:w:",["input_string=","placeholder=","start=","end=","zeropad=","write="])
    except getopt.GetoptError:
        print('HOW TO USE: string_increment.py -i <string_with_placeholder> -p <placeholder> -s <int> -e <int> -z <int> -w <Y|n>')
        sys.exit(2)
    for opt, arg in opts:
        if opt == '-h':
            print('HOW TO USE: string_increment.py -i <string_with_placeholder> -p <placeholder> -s <int> -e <int> -z <int> -w <Y|n>')
            sys.exit()
        elif opt in ("-i", "--input_string"):
            user_string = str(arg)
        elif opt in ("-p", "--placeholder"):
            placeholder = str(arg)
        elif opt in ("-s", "--start"):
            start = int(arg)
        elif opt in ("-e", "--end"):
            stop = int(arg)
        elif opt in ("-z", "--zeropad"):
            padding = int(arg)
        elif opt in ("-w", "--write"):
            save_file = str(arg)
   
    return user_string, placeholder, start, stop, padding, save_file

def string_increment( my_string, placeholder, start, stop, padding=0):
    """ Increment string """
    
    placeholder = re.escape(placeholder)
    str_list = []
    for i in range(start,stop+1):
        nmbr = str(i).zfill(padding)
        str_list.append( re.sub(placeholder,nmbr,my_string) )
    
    return str_list

def write_to_text_file( string_list, save_option='Y' ):
    """ Write to text file """
    
    if(save_option=='Y'):
        # Save to output file
        file_name = 'SI_' + datetime.datetime.now().strftime("%d-%m-%Y_%H-%M-%S") + '.txt'
        with open(file_name, 'w') as f:
            for item in string_list:
                f.write("%s\n" % item)
                
        print("File was saved as `{}`".format(file_name))
    else:
        # Print to console
        print('\n'.join(string_list))

if __name__ == "__main__":
    """ Main string increment """
    # Check input
    my_string, my_placeholder, start, stop, padding, save_it = call_main(sys.argv[1:])
    # Increment string
    result = string_increment(my_string, my_placeholder, start, stop, padding)   
    # Write to text file in executing directory
    write_to_text_file(result, save_it)
    
# Call from CMD/Terminal
$ python string_incrementer.py -i "Hello World [x].mp4" -p "[x]" -s 1 -e 23 -z 2 -w N

"""
Hello World 01.mp4
Hello World 02.mp4
Hello World 03.mp4
Hello World 04.mp4
Hello World 05.mp4
Hello World 06.mp4
Hello World 07.mp4
Hello World 08.mp4
Hello World 09.mp4
Hello World 10.mp4
Hello World 11.mp4
Hello World 12.mp4
Hello World 13.mp4
Hello World 14.mp4
Hello World 15.mp4
Hello World 16.mp4
Hello World 17.mp4
Hello World 18.mp4
Hello World 19.mp4
Hello World 20.mp4
Hello World 21.mp4
Hello World 22.mp4
Hello World 23.mp4
"""