How to save latest time stamp in a file?

[snippsat]

Did look more this so i did write an improved version,battle tested in Windows and Linux.
Now do a recursive scan in folder with pathlib, os.walk in combination with glob.
So now can choice to watch all files or only a file extension eg deb, txt, jpg, ect...
The setup has been made easy.

# watch_folder.py
import os, sys
import platform
import logzero
from logzero import logger
from pathlib import Path, PurePath
 
def newest_file(folder_to_watch, file_extension):
    if file_extension == '*':
        fn = []
        for root, dirs, files in os.walk(folder_to_watch):
            for file in files:
                fn.append(os.path.join(root, file))
        try:
            return max(fn, key=os.path.getctime)
        except ValueError:
            print('No file in folder')
            sys.exit()
    else:
        paths = []
        for filename in Path(folder_to_watch).glob(f'**/*.{file_extension}'):
            paths.append(filename)
        try:
            return max(paths, key=os.path.getctime)          
        except ValueError:
            print(f'No file with extension <{file_extension}>')
            sys.exit()
 
def stamp(newest_file):
    file_stamp = os.path.getmtime(newest_file)
    return file_stamp, newest_file
 
def file_compare(file_stamp, file_name, log_folder):
    # 3 rotations, each with a maximum filesize of 1MB
    logzero.logfile(f"{log_folder}logfile.log",
        maxBytes=1e6, backupCount=3, disableStderrLogger=True)
    try:
        with open(f'{log_folder}stamp.txt') as f:
            old_stamp = float(f.read())
        if old_stamp == file_stamp:
            print(f'No change: {file_name} --> {file_stamp}')
        else:
            print(f'New file: {repr(file_name)} --> {file_stamp}')
            logger.info(f'{file_name} --> {file_stamp}')
            with open(f'{log_folder}stamp.txt', 'w') as f:
                f.write(str(file_stamp))
    except OSError:
        with open(f'{log_folder}stamp.txt', 'w') as f:
            f.write(str(file_stamp))
 
if __name__ == '__main__':
    #--- Setup ---#
    folder_to_watch = '/home/tom/Documents/test_folder/'
    # Watch a spesific file extensions,eg txt, jpg, zip, ect...
    # All files default *
    file_extension = '*'
    # Folder to save filestamp and log file
    log_folder = '/home/tom/Documents/stamp/'
    #---#
    newest_file = newest_file(folder_to_watch, file_extension)
    file_stamp = stamp(newest_file)[0]
    file_name = os.path.basename(stamp(newest_file)[1])
    #--- Start ---#
    file_compare(file_stamp, file_name, log_folder)

For and all Python schedule solution can use schedule.

import subprocess
import schedule
import time
 
def watch_folder():
    subprocess.run(['python', 'watch_folder.py'])
 
if __name__ == '__main__':
    schedule.every(.1).minutes.do(watch_folder)
    while True:
        schedule.run_pending()
        time.sleep(1)

So can call it a very lite version of watchdog.
Watchdog handles many filesystem events and can also execute shell command.