simple example of kevent in python. Simply notes when a monitored file is deleted or renamed.

file_rename.py

#!/usr/local/bin/python

import select
from select import kqueue, kevent
import os
import sys

filename = "access.log"
fd = os.open(filename,os.O_RDONLY)
kq = kqueue()

event = [
    kevent(fd, 
           filter=select.KQ_FILTER_READ,
           flags=select.KQ_EV_ADD),
    kevent(fd, 
           filter=select.KQ_FILTER_VNODE,
           flags=select.KQ_EV_ADD | select.KQ_EV_CLEAR,
	   fflags=select.KQ_NOTE_DELETE | select.KQ_NOTE_RENAME)
]

events = kq.control(event,0,0)

while True:
    print "loop"
    r_events = kq.control(None,4)
    for event in r_events:
        print event
        for event in r_events:
            if event.fflags & select.KQ_NOTE_DELETE:
                print "file was deleted"
            elif event.fflags & select.KQ_NOTE_RENAME:
                print "file was renamed"
            
kq.close()
os.close(fd)