In Python, how can I get the correctly-cased path for a file?

Ned's GetLongPathName answer doesn't quite work (at least not for me). You need to call GetLongPathName on the return value of GetShortPathname. Using pywin32 for brevity (a ctypes solution would look similar to Ned's):

>>> win32api.GetLongPathName(win32api.GetShortPathName('stopservices.vbs'))
'StopServices.vbs'

Ethan answer correct only file name, not subfolders names on the path. Here is my guess:

def get_actual_filename(name):
    dirs = name.split('\\')
    # disk letter
    test_name = [dirs[0].upper()]
    for d in dirs[1:]:
        test_name += ["%s[%s]" % (d[:-1], d[-1])]
    res = glob.glob('\\'.join(test_name))
    if not res:
        #File not found
        return None
    return res[0]

This one unifies, shortens and fixes several approaches: Standard lib only; converts all path parts (except drive letter); relative or absolute paths; drive letter'ed or not; tolarant:

def casedpath(path):
    r = glob.glob(re.sub(r'([^:/\\])(?=[/\\]|$)', r'[\1]', path))
    return r and r[0] or path

And this one handles UNC paths in addition:

def casedpath_unc(path):
    unc, p = os.path.splitunc(path)
    r = glob.glob(unc + re.sub(r'([^:/\\])(?=[/\\]|$)', r'[\1]', p))
    return r and r[0] or path

This python-win32 thread has an answer that doesn't require third-party packages or walking the tree:

import ctypes

def getLongPathName(path):
    buf = ctypes.create_unicode_buffer(260)
    GetLongPathName = ctypes.windll.kernel32.GetLongPathNameW
    rv = GetLongPathName(path, buf, 260)
    if rv == 0 or rv > 260:
        return path
    else:
        return buf.value