Monitor Changing file in python - monitoring

Question

How to create a program that monitors a file (for example, text, and when you wrote something new to this file, the program should output that something was added to the file, and when, on the contrary, part of the text was deleted from it, it should write that something was deleted
And it should print to the console exactly which words were deleted or added?

Answer 1

Explanation
I use watchdog to follow the file.
On instantiation of the handler, I read the file's size.
When the file is modified, watchdog calls the on_modified function.
When this method is called, I compare the file's current size to its previous size to determine if the change was additive or subtractive.
You have a few other options when it comes to tracking the file. For example, you could also compare:
the number of lines
the number of words
the number of characters
the exact contents of the file
import os
import time
from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler
class EventHandler(FileSystemEventHandler):
def __init__(self, file_path_to_watch):
self.file_path_to_watch = file_path_to_watch
self._file_size = self._read_file_size()
def _read_file_size(self):
return os.path.getsize(self.file_path_to_watch)
def _print_change(self, new_file_size):
if new_file_size > self._file_size:
print('File modified with additions')
elif new_file_size < self._file_size:
print('File modified with deletions')
def on_modified(self, event):
if event.src_path != self.file_path_to_watch:
return
new_file_size = self._read_file_size()
self._print_change(new_file_size)
self._file_size = new_file_size
if __name__ == "__main__":
file_to_watch = '/path/to/watch.txt'
event_handler = EventHandler(file_to_watch)
observer = Observer()
observer.schedule(event_handler, path=file_to_watch, recursive=False)
observer.start()
try:
while True:
time.sleep(1)
except KeyboardInterrupt:
observer.stop()
observer.join()