1. os module has os.getcwd() and os.chdir()¹ functions, note that When calling the os.chdir() function, use a Linux-style pathname (forward slashes, no drive letter) even on Windows.
   eg:
   os.chdir(‘/Users/pilgrim/diveintopython3/examples’)
2. os.path.join() will take any number of arguments and os.path.expanduser() function will expand a pathname that uses ~ to represent the current user’s home directory.
3. os.path.split() return a tuple of two variables (the directory name and the filename), and splitext() will return name and extension.
4. the glob function can be used to get the contents of a directory using wildcards. consult glob reference here or here.
5. get metadata of a file using os.stat()²:

   >>> metadata = os.stat('feed.xml')
   >>> metadata.st_size
   3070
   

6. list and dictionary comprehnsions are easy ways to construct new lists and dictionaries based on given ones.

A comprehensive usage example

>>> import os, glob
>>> glob.glob('*.xml')
['feed-broken.xml', 'feed-ns0.xml', 'feed.xml']
>>> [os.path.realpath(f) for f in glob.glob('*.xml') if os.stat(f).st_size > 1000]
['c:\\Users\\pilgrim\\diveintopython3\\examples\\feed-broken.xml',
'c:\\Users\\pilgrim\\diveintopython3\\examples\\feed-ns0.xml',
'c:\\Users\\pilgrim\\diveintopython3\\examples\\feed.xml']