increment_filename looks in path for the file filename.ext or filename(#any number).ext and return:

  • filename.ext: if nothing is found
  • filename(2).ext: if only filename.ext is found
  • filename(n+1).ext: if filename(n).ext is found (with n being the maximum in the folder)
from glob import glob
import os
import re

def increment_filename(path, filename, ext):
    regex_pattern = '(?<=\()(\d+)(?=\)\.'+ext+'$)'
    files = glob(os.path.join(path, filename+"(*)."+ext))
    if files:
        files.sort()
        new_count = int(re.findall(regex_pattern, os.path.basename(files[-1]))[-1])+1
        new_complete_path = re.sub(regex_pattern, str(new_count), files[-1])
    else:
        single = glob(os.path.join(path, filename+'.'+ext))
        if single:
            new_complete_path = os.path.join(path, filename+'(2).'+ext)
        else:
            new_complete_path = os.path.join(path, filename+'.'+ext)
    return new_complete_path

new_path = increment_filename(path="my_path", filename="my_file", ext="txt")

f = open(new_path, 'w')
f.writelines("I am a really nice file!!!")
f.close()