Monitor new files in a directory for changes.

PollingDemo.py

####
# Monitor new files in a directory for changes.
####

import os, time

# basic ideas from here:
# http://timgolden.me.uk/python/win32_how_do_i/watch_directory_for_changes.html#poll_with_listdir

dir = "."
originals = os.listdir(dir)
monitoring = {}

while True:
    time.sleep(4)
    print("checking...")
    
    current = os.listdir(dir)
    
    for f in current:
        lastMod = os.path.getmtime(os.path.join(dir, f))
        
        # see if anything is new
        if f not in originals:
            if f not in monitoring.keys():
                print("Found new file:", f)
            elif lastMod > monitoring[f]:
                print("There was an update in:", f)

            # will add f if it's new and record the most recent update time
            monitoring[f] = lastMod

    # check for missing files (they must've been deleted
    for f in list(monitoring):
        # we need to use a copy so we can modify the object while iterating
        if f not in current:
            del monitoring[f]
            print(f, "was deleted.")