Platform independent path concatenation using "/" , "\"?

Question

In python I have variables base_dir and filename. I would like to concatenate them to obtain fullpath. But under windows I should use \ and for POSIX / .

fullpath = "%s/%s" % ( base_dir, filename ) # for Linux

How can I make this platform independent?

possible duplicate of [Platform-independent file paths?](http://stackoverflow.com/questions/6036129/platform-independent-file-paths) — Felix Kling, Jun 06 '12 at 16:59
Possible duplicate of [Platform-independent file paths?](https://stackoverflow.com/questions/6036129/platform-independent-file-paths) — jww, Aug 24 '19 at 05:55
See also [this answer on Why use os.path.join over string concatenation?](https://stackoverflow.com/a/13944874/1078556) — danicotra, May 16 '20 at 09:27

Levon · Accepted Answer · 2012-06-06T17:46:13.460

You want to use os.path.join() for this.

The strength of using this rather than string concatenation etc is that it is aware of the various OS specific issues, such as path separators. Examples:

import os

Under Windows 7:

base_dir = r'c:\bla\bing'
filename = r'data.txt'

os.path.join(base_dir, filename)
'c:\\bla\\bing\\data.txt'

Under Linux:

base_dir = '/bla/bing'
filename = 'data.txt'

os.path.join(base_dir, filename)
'/bla/bing/data.txt'

The os module contains many useful methods for directory, path manipulation and finding out OS specific information, such as the separator used in paths via os.sep

Andrew Clark · Answer 2 · 2012-06-06T17:03:38.820

27

Use os.path.join():

import os
fullpath = os.path.join(base_dir, filename)

The os.path module contains all of the methods you should need for platform independent path manipulation, but in case you need to know what the path separator is on the current platform you can use os.sep.

edited Jun 06 '12 at 17:03

answered Jun 06 '12 at 16:58

Andrew Clark

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1

it is not *full* path if `base_dir` is a relative path (despite OP uses it) – jfs Jun 06 '12 at 17:01
1

Adding an `abspath()` call should make it a full path if there's anything relative in it. – martineau Jun 06 '12 at 17:42
@Andrew Clark, os.sep returns "\\" on Windows, but it still works even if I use "/". Is there any problem if we just use "/"? – multigoodverse Feb 11 '15 at 10:46

score 25 · Answer 3 · answered Mar 14 '17 at 05:22

25

Digging up an old question here, but on Python 3.4+ you can use pathlib operators:

from pathlib import Path

# evaluates to ./src/cool-code/coolest-code.py on Mac
concatenated_path = Path("./src") / "cool-code\\coolest-code.py"

It's potentially more readable than os.path.join() if you are fortunate enough to be running a recent version of Python. But, you also tradeoff compatibility with older versions of Python if you have to run your code in, say, a rigid or legacy environment.

answered Mar 14 '17 at 05:22

70by7

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I am very fond of `pathlib`. However, it is often not installed by default in Python2 installations. If you do not want users to have to go through installing pathlib as well, `os.path.join()` is the simpler way to go. – Marcel Waldvogel Jun 16 '19 at 12:58
The `/` operator is convenient when working with existing objects. When using the constructor directly, you can just pass multiple arguments to construct the path. i.e. `Path("./src", "cool-code", "coolest-code.py")` – Tomerikoo Jun 29 '22 at 08:14

score 11 · Answer 4 · answered Jun 06 '12 at 17:01

11

import os
path = os.path.join("foo", "bar")
path = os.path.join("foo", "bar", "alice", "bob") # More than 2 params allowed.

answered Jun 06 '12 at 17:01

varunl

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score 0 · Answer 5 · answered Nov 25 '14 at 19:21

I've made a helper class for this:

import os

class u(str):
    """
        Class to deal with urls concat.
    """
    def __init__(self, url):
        self.url = str(url)

    def __add__(self, other):
        if isinstance(other, u):
            return u(os.path.join(self.url, other.url))
        else:
            return u(os.path.join(self.url, other))

    def __unicode__(self):
        return self.url

    def __repr__(self):
        return self.url

The usage is:

    a = u("http://some/path")
    b = a + "and/some/another/path" # http://some/path/and/some/another/path

Will this not insert backslashes on Windows? – Marcel Waldvogel Jun 16 '19 at 12:58 — Marcel Waldvogel, Jun 16 '19 at 12:58

score 0 · Answer 6 · answered Jun 12 '20 at 14:05

Thanks for this. For anyone else who sees this using fbs or pyinstaller and frozen apps.

I can use the below which works perfect now.

target_db = os.path.join(os.path.abspath(os.path.dirname(sys.argv[0])), "sqlite_example.db")

I was doing this fugliness before which was obviously not ideal.

if platform == 'Windows':
    target_db = (os.path.abspath(os.path.dirname(sys.argv[0])) + "\\" + "sqlite_example.db")

if platform == 'Linux' or 'MAC':
    target_db = (os.path.abspath(os.path.dirname(sys.argv[0])) + "/" + "sqlite_example.db")

target_db_path = target_db
print(target_db_path)

Platform independent path concatenation using "/" , "\"?

6 Answers6

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