mkdir -p functionality in Python

For Python ≥ 3.5, use pathlib.Path.mkdir:

import pathlib
pathlib.Path("/tmp/path/to/desired/directory").mkdir(parents=True, exist_ok=True)

The exist_ok parameter was added in Python 3.5.

For Python ≥ 3.2, os.makedirs has an optional third argument exist_ok that, when True, enables the mkdir -p functionality—unless mode is provided and the existing directory has different permissions than the intended ones; in that case, OSError is raised as previously:

import os
os.makedirs("/tmp/path/to/desired/directory", exist_ok=True)

For even older versions of Python, you can use os.makedirs and ignore the error:

import errno    
import os

def mkdir_p(path):
    try:
        os.makedirs(path)
    except OSError as exc:  # Python ≥ 2.5
        if exc.errno == errno.EEXIST and os.path.isdir(path):
            pass
        # possibly handle other errno cases here, otherwise finally:
        else:
            raise

This is easier than trapping the exception:

import os
if not os.path.exists(...):
    os.makedirs(...)

Disclaimer This approach requires two system calls which is more susceptible to race conditions under certain environments/conditions. If you're writing something more sophisticated than a simple throwaway script running in a controlled environment, you're better off going with the accepted answer that requires only one system call.

UPDATE 2012-07-27

I'm tempted to delete this answer, but I think there's value in the comment thread below. As such, I'm converting it to a wiki.

mkdir -p gives you an error if the file already exists:

$ touch /tmp/foo
$ mkdir -p /tmp/foo
mkdir: cannot create directory `/tmp/foo': File exists

So a refinement to the previous suggestions would be to re-raise the exception if os.path.isdir returns False (when checking for errno.EEXIST).

(Update) See also this highly similar question; I agree with the accepted answer (and caveats) except I would recommend os.path.isdir instead of os.path.exists.

(Update) Per a suggestion in the comments, the full function would look like:

import os
def mkdirp(directory):
    if not os.path.isdir(directory):
        os.makedirs(directory) 

I think Asa's answer is essentially correct, but you could extend it a little to act more like mkdir -p, either:

import os

def mkdir_path(path):
    if not os.access(path, os.F_OK):
        os.mkdirs(path)

or

import os
import errno

def mkdir_path(path):
    try:
        os.mkdirs(path)
    except os.error, e:
        if e.errno != errno.EEXIST:
            raise

These both handle the case where the path already exists silently but let other errors bubble up.