Renames files from annoying date format to sane

rename.py

import os
from time import strptime

dir_path = os.path.dirname(os.path.realpath(__file__))
file_list = os.listdir(dir_path)

def rename(file):
        month_name = file.split('-')[0]
        month_num = str(strptime(month_name, '%b').tm_mon).zfill(2)
        
        year_onward = file.split('-')[1]
        new_name = '{}-{}{}'.format(
            year_onward[:4],
            month_num,
            year_onward[4:]
            )
        os.rename(file, new_name)

for file in file_list:
    if file.endswith('.pdf'):
        rename(file)