python – which one should I use: os.sep or os.path.sep?-ThrowExceptions

Exception or error:

They are same, but which one should I use?


The character used by the operating system to separate pathname components. This is ‘/’ for POSIX and ‘\’ for Windows. Note that knowing this is not sufficient to be able to parse or concatenate pathnames — use os.path.split() and os.path.join() — but it is occasionally useful. Also available via os.path.

How to solve:

I’d use os.path.sep to make it very clear that it’s the path separator… But consistency is more important, so if one is already being used, use that. Otherwise, pick one and use it all the time.

Edit: Just to make sure you’re not reinventing the wheel, though, the path module already has join, split, dirname, and basename functions… So you should rarely need to use path.sep:

>>> os.path.join("foo", "bar", "baz")
>>> os.path.split(_)
('foo/bar', 'baz')


I recommend you use os.path.sep for clarity, since it’s a path separator, not an OS separator. If you import os.path as path you can call it path.sep, which is even better.


If you are using Jython 2.7, I suggest using os.sep (works) instead of os.path.sep (broken) as Jython on Windows has a bug returning a "/" slash instead of the required "\" backslash.


The following examples could highlight the differences between os.path.join and os.path.sep.join.

import os
os.path.join(“output”, “images”, “saved”)
os.path.sep.join([“output”, “images”, “saved”])

I guess the os.path.sep.join is more robust and can be used w/o modifications for any os.

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