Monitor Your File System With Python’s Watchdog

Python’s watchdog library makes it straightforward to observe your file system and reply to those adjustments mechanically. Watchdog is a cross-platform API that permits you to run instructions in response to any adjustments within the file system being monitored. We will set triggers on a number of occasions akin to file creation, modification, deletion, and motion, after which reply to those adjustments with our customized scripts.

Setup for Watchdog

You will want two modules to start:

• Watchdog: Run this command beneath within the terminal to put in the watchdog.

   

• Logging: It’s a built-in Python module, so there isn’t any must externally set up it.

Fundamental Utilization

Let’s create a easy script ‘main.py’ that displays a listing and prints a message every time a file is created, modified, or deleted.

Step 1: Import Required Modules

First, import the mandatory modules from the watchdog library:

import time
from watchdog.observers import Observer
from watchdog.occasions import FileSystemEventHandler

Step 2: Outline Occasion Handler Class

We outline a category MyHandler that inherits from FileSystemEventHandler. This class overrides strategies like on_modified, on_created, and on_deleted to specify what to do when these occasions happen. The occasion handler object can be notified when any adjustments occur within the file system.

class MyHandler(FileSystemEventHandler):
    def on_modified(self, occasion):
        print(f'File {occasion.src_path} has been modified')

    def on_created(self, occasion):
        print(f'File {occasion.src_path} has been created')

    def on_deleted(self, occasion):
        print(f'File {occasion.src_path} has been deleted')

Some helpful strategies of FileSystemEventHandler are defined beneath.

• on_any_event: Executed for any occasion.
• on_created: Executed upon creation of a brand new file or listing.
• on_modified: Executed upon modification of a file or when a listing is renamed.
• on_deleted: Triggered upon the deletion of a file or listing.
• on_moved: Triggered when a file or listing is relocated.

Step 3: Initialize and Run the Observer

The Observer class is liable for monitoring the file system for any adjustments and subsequently notifying the occasion handler. It repeatedly tracks file system actions to detect any updates.

if __name__ == "__main__":
    event_handler = MyHandler()
    observer = Observer()
    observer.schedule(event_handler, path=".", recursive=True)
    observer.begin()

    attempt:
        whereas True:
            time.sleep(1)
    besides KeyboardInterrupt:
        observer.cease()
    observer.be part of()

We begin the observer and use a loop to maintain it operating. While you wish to cease it, you possibly can interrupt with a keyboard sign (Ctrl+C).

Step 4: Run the Script

Lastly, run the script with the next command.

Output:

File .File1.txt has been modified
File .New Textual content Doc (2).txt has been created
File .New Textual content Doc (2).txt has been deleted
File .New Textual content Doc.txt has been deleted

The above code will log all of the adjustments within the listing to the terminal if any file/folder is created, modified, or deleted.

Superior Utilization

Within the following instance, we are going to discover the way to arrange a system that detects any change in Python information and run checks for it mechanically. We have to set up pytest with the next command.

Step 1: Create a Easy Python Challenge With Checks

First, arrange the fundamental construction of your venture:

my_project/
│
├── src/
│   ├── __init__.py
│   └── instance.py
│
├── checks/
│   ├── __init__.py
│   └── test_example.py
│
└── watchdog_test_runner.py

Step 2: Write Code in Instance Python File

Create a easy Python module in src/instance.py:

def add(a, b):
    return a + b

def subtract(a, b):
    return a - b

Step 3: Write the Check Instances

Subsequent, write the take a look at instances for capabilities in checks/test_example.py:

import pytest
from src.instance import add, subtract

def test_add():
    assert add(1, 2) == 3
    assert add(-1, 1) == 0
    assert add(-1, -1) == -2

def test_subtract():
    assert subtract(2, 1) == 1
    assert subtract(1, 1) == 0
    assert subtract(1, -1) == 2

Step 4: Write the Watchdog Script

Now, create the watchdog_test_runner.py script to observe adjustments in Python information and mechanically run checks:

import time
import subprocess
from watchdog.observers import Observer
from watchdog.occasions import FileSystemEventHandler

class TestRunnerHandler(FileSystemEventHandler):
    def on_modified(self, occasion):
        if occasion.src_path.endswith('.py'):
            self.run_tests()

    def run_tests(self):
        attempt:
            outcome = subprocess.run(['pytest'], examine=False, capture_output=True, textual content=True)
            print(outcome.stdout)
            print(outcome.stderr)
            if outcome.returncode == 0:
                print("Tests passed successfully.")
            else:
                print("Some tests failed.")
        besides subprocess.CalledProcessError as e:
            print(f"Error running tests: {e}")

if __name__ == "__main__":
    path = "."  # Listing to look at
    event_handler = TestRunnerHandler()
    observer = Observer()
    observer.schedule(event_handler, path, recursive=True)
    
    observer.begin()
    print(f"Watching for changes in {path}...")

    attempt:
        whereas True:
            time.sleep(1)
    besides KeyboardInterrupt:
        observer.cease()
    
    observer.be part of()

Step 5: Run the Watchdog Script

Ultimately, open a terminal, navigate to your venture listing (my_project), and run the watchdog script:

python watchdog_test_runner.py

Output:

Looking ahead to adjustments in ....
========================= take a look at session begins =============================
platform win32 -- Python 3.9.13, pytest-8.2.1, pluggy-1.5.0
rootdir: F:Net Devwatchdog
plugins: anyio-3.7.1
collected 2 gadgets

teststest_example.py ..                                                 [100%]

========================== 2 handed in 0.04s ==============================

Checks handed efficiently.

This output exhibits that every one the take a look at instances are handed after adjustments had been made to instance.py file.

Summing Up

Python’s watchdog library is a robust device for monitoring your file system. Whether or not you are automating duties, syncing information, or constructing extra responsive purposes, watchdog makes it straightforward to react to file system adjustments in actual time. With just some traces of code, you can begin monitoring directories and dealing with occasions to streamline your workflow.

Kanwal Mehreen Kanwal is a machine studying engineer and a technical author with a profound ardour for information science and the intersection of AI with medication. She co-authored the e-book “Maximizing Productivity with ChatGPT”. As a Google Technology Scholar 2022 for APAC, she champions variety and educational excellence. She’s additionally acknowledged as a Teradata Variety in Tech Scholar, Mitacs Globalink Analysis Scholar, and Harvard WeCode Scholar. Kanwal is an ardent advocate for change, having based FEMCodes to empower girls in STEM fields.