Ответ 1

os.path.isfile("bob.txt") # Does bob.txt exist?  Is it a file, or a directory?
os.path.isdir("bob")

Ответ 3

Многие из функций каталога Python находятся в os.path module.

import os
os.path.isdir(d)

Ответ 4

Образовательный пример из stat:

import os, sys
from stat import *

def walktree(top, callback):
    '''recursively descend the directory tree rooted at top,
       calling the callback function for each regular file'''

    for f in os.listdir(top):
        pathname = os.path.join(top, f)
        mode = os.stat(pathname)[ST_MODE]
        if S_ISDIR(mode):
            # It a directory, recurse into it
            walktree(pathname, callback)
        elif S_ISREG(mode):
            # It a file, call the callback function
            callback(pathname)
        else:
            # Unknown file type, print a message
            print 'Skipping %s' % pathname

def visitfile(file):
    print 'visiting', file

if __name__ == '__main__':
    walktree(sys.argv[1], visitfile)