You can use
os.path.isfile() to check both whether a name both exists and is a file:
from os.path import isfile if isfile('file.txt'): # Do something with file.txt
To check for the existence of any type of filesystem object, use
from os.path import exists if exists('path'): # Do something with path
Note that it isn’t a good idea to check for a file’s existence before opening it – it’s a race condition, with the file able to disappear in-between you testing for its existence and opening it.
It’s much better (and more Pythonic) to just try to open it and handle failure:
try: with open('file.txt') as f: # Do something with f except IOError as err: # Handle the err