python - mixed slashes with os.path.join on windows

Question

I tend to use only forward slashes for paths ('/') and python is happy with it also on windows. In the description of os.path.join it says that is the correct way if you want to go cross-platform. But when I use it I get mixed slashes:

import os

a = 'c:/'
b = 'myFirstDirectory/'
c = 'mySecondDirectory'
d = 'myThirdDirectory'
e = 'myExecutable.exe'


print os.path.join(a, b, c, d, e)

# Result:
c:/myFirstDirectory/mySecondDirectory\myThirdDirectory\myExecutable.exe

Is this correct? Should I check and correct it afterward or there is a better way?

Thanks

EDIT: I also get mixed slashes when asking for paths

import sys
for item in sys.path:
    print item

# Result:
C:\Program Files\Autodesk\Maya2013.5\bin
C:\Program Files\Autodesk\Maya2013.5\mentalray\scripts\AETemplates
C:\Program Files\Autodesk\Maya2013.5\Python
C:\Program Files\Autodesk\Maya2013.5\Python\lib\site-packages
C:\Program Files\Autodesk\Maya2013.5\bin\python26.zip\lib-tk
C:/Users/nookie/Documents/maya/2013.5-x64/prefs/scripts
C:/Users/nookie/Documents/maya/2013.5-x64/scripts
C:/Users/nookie/Documents/maya/scripts
C:\Program Files\Nuke7.0v4\lib\site-packages
C:\Program Files\Nuke7.0v4/plugins/modules

Answer 1

You are now providing some of the slashes yourself and letting os.path.join pick others. It's better to let python pick all of them or provide them all yourself. Python uses backslashes for the latter part of the path, because backslashes are the default on Windows.

import os

a = 'c:' # removed slash
b = 'myFirstDirectory' # removed slash
c = 'mySecondDirectory'
d = 'myThirdDirectory'
e = 'myExecutable.exe'

print os.path.join(a + os.sep, b, c, d, e)

I haven't tested this, but I hope this helps. It's more common to have a base path and only having to join one other element, mostly files.

By the way; you can use os.sep for those moments you want to have the best separator for the operating system python is running on.

Edit: as dash-tom-bang states, apparently for Windows you do need to include a separator for the root of the path. Otherwise you create a relative path instead of an absolute one.

Answer 2

You can use .replace() after path.join() to ensure the slashes are correct:

# .replace() all backslashes with forwardslashes
print os.path.join(a, b, c, d, e).replace("\\","/")

This gives the output:

c:/myFirstDirectory/mySecondDirectory/myThirdDirectory/myExecutable.exe

As @sharpcloud suggested, it would be better to remove the slashes from your input strings, however this is an alternative.

Answer 3

try using abspath (using python 3)

import os

a = 'c:/'
b = 'myFirstDirectory/'
c = 'mySecondDirectory'
d = 'myThirdDirectory'
e = 'myExecutable.exe'


print(os.path.abspath(os.path.join(a, b, c, d, e)))

OUTPUT:

c:\myFirstDirectory\mySecondDirectory\myThirdDirectory\myExecutable.exe

Process finished with exit code 0

Answer 4

EDIT based on comment: path = os.path.normpath(path)

My previous answer lacks the capability of handling escape characters and thus should not be used:

• First, convert the path to an array of folders and file name.

• Second, glue them back together using the correct symbol.

  import os   
  path = 'c:\www\app\my/folder/file.php'
  # split the path to parts by either slash symbol:
  path = re.compile(r"[\/]").split(path)
  # join the path using the correct slash symbol:
  path = os.path.join(*path)
  

Answer 5

If for any reason you need to provide the paths yourself and you have using anything above python 3.4 you can use pathlib

from pathlib import Path, PurePosixPath

a = PurePosixPath('c:/')
b = PurePosixPath('myFirstDirectory/')
c = 'mySecondDirectory'
d = 'myThirdDirectory'
e = 'myExecutable.exe'

print(a / b / c / d / e)

# Result
c:/myFirstDirectory/mySecondDirectory/myThirdDirectory/myExecutable.exe

I used this when I needed a user to provide the location of an assets directory and my code was looking up using windows path strings

In [1]: from pathlib import Path, PureWindowsPath
In [2]: USER_ASSETS_DIR = Path('/asset/dir') # user provides this form environment variable
In [3]: SPECIFIC_ASSET = PureWindowsPath('some\\asset')
In [4]: USER_ASSETS_DIR / SPECIFIC_ASSET

Out[4]: PosixPath('/asset/dir/some/asset')

Answer 6

os adds slashes for you and makes sure not to duplicate slashes so omit them in your strings

import os

# Don't add your own slashes
a = 'C:'
b = 'myFirstDirectory' 
c = 'mySecondDirectory'
d = 'myThirdDirectory'
e = 'myExecutable.exe'

print os.path.join(a, b, c, d, e)
C:\myFirstDirectory\mySecondDirectory\myThirdDirectory\myExecutable.exe

Additional:

I'm unsure as to why you have mixed slashes in your sys path (have you used a linux os to add some folders?) but try checking

print os.path.isdir(os.path.join('C:','Users','nookie')).

If this is True then os works for your mixed slashes.

Either way, I would avoid hard-coding directory names into your program. Your sys.path for loop is a safe way to pull out these directories. You can then use some string methods, or regex to pick the desired folder.

Answer 7

Postgres command client psql doesn't accept back slashes even on Windows:

>psql -U user -h 111.111.111.111 -d mydb
psql (12.2, server 12.5 . . .
. . .
mydb=> \i C:\my\path\myscript.sql
C:: Permission denied

So needed to fix it when executing from Python 3.8.6. Didn't want to resort to naive string replacement and used existing function:

script_path = Path(script_dir).resolve()
input_sql = f'\\i {script_path.joinpath("myscript.sql").as_posix()}\n'

But under the hood it has:

# ...\Programs\Python\Python38\Lib\pathlib.py
    def as_posix(self):
        """Return the string representation of the path with forward (/)
        slashes."""
        f = self._flavour
        return str(self).replace(f.sep, '/')

Answer 8

You can also do this:

import re

a = 'c:/'
b = 'myFirstDirectory/'
c = 'mySecondDirectory'
d = 'myThirdDirectory'
e = 'myExecutable.exe'

joined = os.path.join(a, b, c, d, e)
formatted = re.sub(r'/|\\', re.escape(os.sep), joined)

This is going to switch all your potentially mixed slashes into OS compliant ones.

I know it's an ancient topic but I couldn't resist. :)

Answer 9

The way I do it is fairly straightforward: rstrip all the paths from their slashes, regardless of quantity and correctness, add join those paths back using the correct separator.

import os

def join_path_regardless_of_separators(*paths):
    return os.path.sep.join(path.rstrip(r"\/") for path in paths)
 
a = 'c:/'
b = 'myFirstDirectory/'
c = 'mySecondDirectory'
d = 'myThirdDirectory\\\\\\/'
e = 'myExecutable.exe'
join_path_regardless_of_separators(a, b, c, d, e)
>>> 'c:\\myFirstDirectory\\mySecondDirectory\\myThirdDirectory\\myExecutable.exe'

Another way to use it, for the same result:

join_path_regardless_of_separators(*"""c:////\\\\
                                       myFirstDirectory/
                                       mySecondDirectory\\\\
                                       myThirdDirectory/////
                                       myExecutable.exe
                                    """.split())