import os

# Renames the filenames within all subdirectories

# Usage:
# python filename_lowercase.py

directory_to_check = os.getcwd()

def rename():
      path = os.getcwd()
      filenames = os.listdir(path)

      for filename in filenames:
         os.rename(filename, filename.lower())

directories = [os.path.abspath(x[0]) for x in os.walk(directory_to_check)]
directories.remove(os.path.abspath(directory_to_check))

for i in directories:
      os.chdir(i)
      rename()