[Tutor] Directory notification

[Hugo González Monteverde]

Hi all,

I was writing a daemon to continuously check for changes in a directory 
and then process the new files, I was polling every X seconds, but I 
decided I should give dnotify a try in Python. Here is my test program, 
I just want to share it with others on the list, as it is a very nice 
way to watch a directory as polling is ugly (it is Linux specific, though)

==========
#!/usr/bin/env python
# This checks the implementation for dnotify, uses fcntl and signals

import signal
from fcntl import *
import os

#set event handler for SIGIO, otherwise the program will terminate
signal.signal(signal.SIGIO, lambda signum, stack:None)

# Configure fcntl for a directory
# wanted: DN_MODIFY DN_CREATE DN_ATTRIB DN_DELETE DN_RENAME DN_MULTISHOT
dnot_dir = "/var/data/in"

# builtin open() will refuse to open a directory(!)
filep = os.open(dnot_dir, os.O_RDONLY)

while True:
     # register the service
     fcntl(filep, F_NOTIFY,
           DN_MODIFY|DN_CREATE|DN_ATTRIB|DN_DELETE|DN_RENAME)

     # block until signal is received
     signal.pause()
     print "EVENT!"

=================