mkdir -p functionality in Python [duplicate]

Answer 1

Recently, I found this distutils.dir_util.mkpath:

In [17]: from distutils.dir_util import mkpath

In [18]: mkpath('./foo/bar')
Out[18]: ['foo', 'foo/bar']

Answer 2

As mentioned in the other solutions, we want to be able to hit the file system once while mimicking the behaviour of mkdir -p. I don't think that this is possible to do, but we should get as close as possible.

Code first, explanation later:

import os
import errno

def mkdir_p(path):
    """ 'mkdir -p' in Python """
    try:
        os.makedirs(path)
    except OSError as exc:  # Python >2.5
        if exc.errno == errno.EEXIST and os.path.isdir(path):
            pass
        else:
            raise

As the comments to @tzot's answer indicate there are problems with checking whether you can create a directory before you actually create it: you can't tell whether someone has changed the file system in the meantime. That also fits in with Python's style of asking for forgiveness, not permission.

So the first thing we should do is try to make the directory, then if it goes wrong, work out why.

As Jacob Gabrielson points out, one of the cases we must look for is the case where a file already exists where we are trying to put the directory.

With mkdir -p:

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

The analogous behaviour in Python would be to raise an exception.

So we have to work out if this was the case. Unfortunately, we can't. We get the same error message back from makedirs whether a directory exists (good) or a file exists preventing the creation of the directory (bad).

The only way to work out what happened is to inspect the file system again to see if there is a directory there. If there is, then return silently, otherwise raise the exception.

The only problem is that the file system may be in a different state now than when makedirs was called. eg: a file existed causing makedirs to fail, but now a directory is in its place. That doesn't really matter that much, because the the function will only exit silently without raising an exception when at the time of the last file system call the directory existed.

Answer 3

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) 

Answer 4

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.

Answer 5

import os
import tempfile

path = tempfile.mktemp(dir=path)
os.makedirs(path)
os.rmdir(path)

Answer 6

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
        else:
            raise