I have a few important files that I would like to preserve, so I make multiple backups of them. In order to check their integrity, I decided to write a python script that would help me with this task.

It does exactly what it should, it traverses a directory tree starting from where the script is executed, calculates the hashes of the files it finds and writes them to a text file. It can also calculate the hashes again and check them against the ones that are in the text file.

import hashlib import os import sys  # Description of a hashlist element: # hashlist[0] = (SHA1_HASH, PARTIAL_FILE_PATH) # Partial file path is used in order to keep the script # cross platform; every time the full file path is  # needed, the current working directory gets added to  # the partial file path  # parameters: filename (full path) # reads it in 4096 bytes chunks and feeds them to the sha1 function # returns the sha1 hash # PS I got this code snippet from stackoverflow  def sha1(fname):   hash_sha1 = hashlib.sha1()   with open(fname, "rb") as f:     for chunk in iter(lambda: f.read(4096), b""):       hash_sha1.update(chunk)   return hash_sha1.hexdigest()  # parameters: a path, verbose flag (false if message is not needed) # walks the directory tree generated by the os.walk method, creates  # a hashlist # returns the created hashlist  def create_hashlist_from_path(path, verbose=True):   hashlist = []   ignored_files = ['directoryTree_integrity_check.py', 'directory.sha1'] # add here the files you want to exclude from the integrity check   for root, dirs, files in os.walk(path):     files.sort() # preventing unexpected results by sorting the file names first     for name in files:       if (name not in ignored_files):         path_to_be_written = root         path_to_be_written = path_to_be_written.replace(path, "")         # removing the '/' at the beginning else os.path.join treats it as an absolute path         # which is not what we want         if path_to_be_written.startswith('\'):           path_to_be_written = path_to_be_written[1:]         hashlist.append(((sha1(os.path.join(root, name)), os.path.join(path_to_be_written, name)))) # appends a new sha1 digest - file path tuple to the list         if verbose == True:           print(name + " Done")   return hashlist  # parameters: a hashlist # writes the sha1 hash of the file and the partial file path itself to file, in this order   # and one per line # function is void  def write_hashlist_to_file(hashlist):   with open('directory.sha1', 'w+') as f:     for couple in hashlist:       f.write(couple[0] + ' ' + couple[1] + '\n')   return  # parameters: none # reads file line by line, strips the trailing newline from it  # splicing is used to separate sha1 hash from partial file path # returns the parsed hashlist  def parse_hashlist_file():   hashlist = []   with open('directory.sha1', 'r') as f:     for line in f:       line = line.strip()       sha1_hash = line[:40]       file_path = line[41:]       hashlist.append((sha1_hash, file_path))   hashlist = add_cwd_to_hashlist(hashlist)   return hashlist  # parameters: a hashlist # adds the cwd to the partial file path  # returns the fixed hashlist  def add_cwd_to_hashlist(hashlist):   new_hashlist = []   for couple in hashlist:     new_hashlist.append((couple[0], (os.path.join(cwd, couple[1]))))   return new_hashlist  def create_and_write_hashlist_to_file():   print("Calculating hashes...")   hashlist = create_hashlist_from_path(cwd)   print("Writing hashes to file...")   write_hashlist_to_file(hashlist)   print("Done")   return  def print_menu():   print("1. Calculate and write SHA1 hashes to file")   print("2. Calculate SHA1 hashes and check them against file")   print("3. Exit")   if __name__ == '__main__':    cwd = os.getcwd()   menu_choice = 0   print_menu()    while menu_choice != 3:     print("Type in your choice:")      # check if the menu_choice is different from the 3 allowed     while True:       try:         menu_choice = int(input('>'))       except ValueError:         pass       if (menu_choice > 0 or menu_choice < 4):         break      if menu_choice == 1:       # check if 'directory.sha1' exists first       if os.path.isfile('directory.sha1'):         print("SHA1 hashes file exists already")         print("Do you want to overwrite it? y/n")         response = input()         if response == 'y':           create_and_write_hashlist_to_file()       else:         create_and_write_hashlist_to_file()      elif menu_choice == 2:       # check if 'directory.sha1' does not exist       if not os.path.isfile('directory.sha1'):         print("SHA1 hashes file has not been found")         print("Do you want to create it? y/n")         response = input()         # basically do what menu_choice 1 does         if response == 'y':           create_and_write_hashlist_to_file()       # 'directory.sha1' exist       else:         mismatch_number = 0         # parse it         parsed_hashlist = parse_hashlist_file()         # check parsed data against what we calculate in every iteration         print("Checking...")         for couple in parsed_hashlist:           try:             if couple[0] != sha1(couple[1]):               # print("MISMATCH " + '"' + couple[1][ ( (couple[1].rfind('\') ) + 1) : ] + '"')               print("MISMATCH " + '"' + couple[1] + '"')               mismatch_number += 1           except FileNotFoundError:             print("File" + ' " ' + couple[1] + ' " ' + "has not been found" )             mismatch_number += 1          if mismatch_number == 0:           print("All files match")      elif menu_choice == 3:       pass    print("Exiting...")   sys.exit(0) 

I would like to know though if there is something that I could have done better/written more efficiently and if my codestyle and comments are somewhat acceptable.

Thank you in advance for the criticism.