Create a watchdog timer in Python to look for changes in the filesystem

_files | File handling | Python functions | system

Michael Zippo 18.07.2021

Many times a file must be processed during its creation or modification. This can be done by following the changes in a specific directory. There are many ways in python to keep track of changes made to a directory. One such way is to use the watchdog module. As the name suggests, this module monitors the given directory and can notify if a file is created or modified.

Required Modules

Guard Dog
To install the watchdog, run this command in a terminal.
```
 pip install watchdog 
```
logging
It comes with Python, so no need install it externally.

Now let’s dive into the code that will log all the logged changes. This code will only log changes checked in to the current directory.

# import modules

import sys

import time

import logging

from watchdog.observers import Observer

from watchdog.events import LoggingEventHandler

if __ name__ = = " __ main__ " :

# Set the format for logging information

logging.basicConfig (level = logging.INFO,

format = ’% (asctime) s -% (message) s’ ,

datefmt = ’% Y-% m-% d% H:% M:% S’ )

# Install format for displaying the path

path = sys.argv [ 1 ] if len (sys.argv)" 1 else ’.’

# Initialize registration event handler

event_handler = LoggingEventHandler ()

# Initialize Observer

observer = Observer ()

observer.schedule (event_handler, path, recursive = True )

# Start observer

observer.start ()

try :

while True :

# Set stream timeout

time.sleep ( 1 )

except KeyboardInterrupt:

observer.stop ()

observer.join ()

Output:

The above code will log all changes registered to the directory. If you want to make changes while creating or modifying a file, you can do so using the following code.

# import time module, Observer, FileSystemEventHandler

import time

from watchdog.observers import Observer

from watchdog.events import FileSystemEventHandler

class OnMyWatch:

# Set directory to watch

watchDirectory = "/ give / the / address / of / directory"

def __ init __ ( self ):

self .observer = Observer ()

def run ( self ):

event_handler = Handler ()

self . observer.schedule (event_handler, self . watchDirectory, recursive = True )

self . observer .start ()

try :

while True :

time.sleep ( 5 )

except :

self . observer.stop ()

print ( "Observer Stopped" )

self . observer.join ()

class Handler (FileSystemEventHandler):

@ staticmethod

def on_any_event (event):

if event.is_directory:

return None

elif event.event_type = = ’created’ :

# The event was created, you can process it now

print ( "Watchdog received created event -% s." % event.src_path)

elif event.event_type = = ’modified’ :

# The event has been changed, you can handle it now

print ( " Watchdog received modified event -% s. " % event.src_path)

if __ name__ = = ’ __main__’ :

watch = OnMyWatch ()

watch.run ()

Output: