Watchdog is a handy Python package which uses the inotify Linux kernel subsystem to watch for any changes to the filesystem.
This makes it an excellent foundation to build a a small script which takes action whenever a file is received in a directory, or any of the directory's contents change. An example might be a client-facing sftp server where you may want to receive an email when a file is received.
I've included a shortened version of a watcher.py script I used for just such a purpose. There are 2 main classes:
Watcher - this waits for any events on the watched directory
Handler - this is the event handler that takes action when an event is received
import time
from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler
class Watcher:
DIRECTORY_TO_WATCH = "/path/to/my/directory"
def __init__(self):
self.observer = Observer()
def run(self):
event_handler = Handler()
self.observer.schedule(event_handler, self.DIRECTORY_TO_WATCH, recursive=True)
self.observer.start()
try:
while True:
time.sleep(5)
except:
self.observer.stop()
print "Error"
self.observer.join()
class Handler(FileSystemEventHandler):
@staticmethod
def on_any_event(event):
if event.is_directory:
return None
elif event.event_type == 'created':
# Take any action here when a file is first created.
print "Received created event - %s." % event.src_path
elif event.event_type == 'modified':
# Taken any action here when a file is modified.
print "Received modified event - %s." % event.src_path
if __name__ == '__main__':
w = Watcher()
w.run()
To use this, just run python watcher.py from your console. If you open any console window and upload a file or make any changes, you will see this printed out in your original console window.
To actually make this useful, you should wrap this up as a daemon or upstart script which can be run indefinitely.