How to save latest time stamp in a file?

[snippsat]

As you know that I need to run the subprocess.Popen() on the latest file. So I assume that I would have to call it under
"def file_compare" function within the "else" block as it the part that is working on the latest file. Or do I need to use that "schedule" module?

Yes you call it under file_compare function.
You do not need to use the schedule can just run watch_folder.py alone or use Cron.
Example:

import subprocess

out = subprocess.run(['ping', 'google.com'], capture_output=True)
print(out.stdout.decode())

Output:
Pinging google.com [172.217.21.174] with 32 bytes of data:
Reply from 172.217.21.174: bytes=32 time=77ms TTL=57
Reply from 172.217.21.174: bytes=32 time=62ms TTL=57
Reply from 172.217.21.174: bytes=32 time=69ms TTL=57
Reply from 172.217.21.174: bytes=32 time=68ms TTL=57

Ping statistics for 172.217.21.174:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 62ms, Maximum = 77ms, Average = 69ms

So if i want to run this in code eg each time a new .txt file is made or can as test use run.txt to activate.

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:
            if file_name == 'run.txt':
                output = subprocess.run(['ping', 'google.com'], capture_output=True)
                print(output.stdout.decode())
            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))

In setup i watch folder eggs and .txt files only.

folder_to_watch = 'E:/eggs'
file_extension = 'txt'

So to test i use schedule(run watch_folder.py every 10-sec) and i make .txt files live.
As soon as i make run.txt the subprocess code will run.