Create file but if name exists add number

Question

Does Python have any built-in functionality to add a number to a filename if it already exists?

My idea is that it would work the way certain OS\'s work - if a file

Answer 1

Let's say I already have those files:

This function generates the next available non-already-existing filename, by adding a _1, _2, _3, etc. suffix before the extension if necessary:

import os

def nextnonexistent(f):
    fnew = f
    root, ext = os.path.splitext(f)
    i = 0
    while os.path.exists(fnew):
        i += 1
        fnew = '%s_%i%s' % (root, i, ext)
    return fnew

print(nextnonexistent('foo.txt'))  # foo_3.txt
print(nextnonexistent('bar.txt'))  # bar_1.txt
print(nextnonexistent('baz.txt'))  # baz.txt