Batch rename.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-


from os import listdir, chdir, rename

# Valid chars in a file name
alpha = 'abcdefghijklmnopqrstuvwxyz0123456789.'
dir_path = "/home/varun/Desktop/Github Projects/CodeKata/Python"

total_files = len(listdir(dir_path))

for i in listdir(dir_path):
    ans = ''
    for j in i:
        if j.lower() in alpha:
            ans += j
        else:
            if j == ' ':
                ans += '_'
    chdir(dir_path)
    rename(i, ans)

# Getting the final count of files in the folder after renaming
final_count = len(listdir(dir_path))

# Final Verification
print('Number of files present initially: ', total_files)
print('Number of file renamed: ', final_count)
print('Difference: ', (total_files - final_count))