cross platform accessing paths (windows, linux ...)

Vlastimil Brom vlastimil.brom at gmail.com
Thu Mar 12 23:51:02 CET 2009


2009/3/12 Christian Heimes <lists at cheimes.de>:
> Vlastimil Brom wrote:
>> def path_from_pardir(path):
>>     return os.path.realpath(os.path.normpath(os.path.join(os.path.dirname(__file__),
>> os.pardir, path)))
>> #  __file__ is substituted with sys.path[0] if not present
>>
>> real_path = path_from_pardir("txt/text_1.txt")
>>
>> The above seems to work both on windows and linux, but it very much
>> looks like woodoo code for me;
>
> The canonical way to get the directory of a Python file is
>
>    os.path.dirname(os.path.abspath(__file__))
>
> __file__ is the relative or absolute path to the .py(c) file.
> os,path.abspath() makes sure it's an absolute path. os.path.dirname()
> returns the name of the directory. I usually store the directory as a
> global name 'HERE'.
>
> >From here on you can traverse the file system.
> os.path.abspath(os.path.join(HERE, os.pardir, somename)) gives you
> "../somename" relative to the directory where your .py(c) is stored.
>
> Christian
>
Thanks for the clarification Christian, it's much clearer this way!
Is it true, that I don't have to bother with realpath(), if I only use
real directories i my program? (lacking the proper experiences with
linux, I don't know, whether the symlinks could be yet otherwhere
(upwards) in the path)
Also, is it the right approach to substitute __file__  with
sys.path[0] if it is not available? (like the executable generated
using py2exe).

thanks again,
   Vlasta



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