How can I safely create a nested directory?

Question

What is the most elegant way to check if the directory a file is going to be written to exists, and if not, create the directory using Python? Here is what I tried:

Answer 1

I would personally recommend that you use os.path.isdir() to test instead of os.path.exists().

>>> os.path.exists('/tmp/dirname')
True
>>> os.path.exists('/tmp/dirname/filename.etc')
True
>>> os.path.isdir('/tmp/dirname/filename.etc')
False
>>> os.path.isdir('/tmp/fakedirname')
False

If you have:

>>> dir = raw_input(":: ")

And a foolish user input:

:: /tmp/dirname/filename.etc

... You're going to end up with a directory named filename.etc when you pass that argument to os.makedirs() if you test with os.path.exists().