Monitor file change for a python script and restart the script automatically.

monitor.py

import pyinotify
import sys
import subprocess
import os
import click

def restart(filename):
    p = subprocess.Popen(['python', filename])
    print("Process ID of subprocess %s" % p.pid)
    return p

class MyEventHandler(pyinotify.ProcessEvent):
    _process = None
    _filename = None

    def process_IN_CLOSE_WRITE(self, event):
        print(event.pathname)
        if os.path.basename(event.pathname) != self._filename:
            return

        if self._process:
            self._process.terminate()
            returncode = self._process.wait()
            print("Returncode of subprocess: %s" % returncode)

        self._process = restart(self._filename)
        print('process restarted')

@click.command()
@click.option('-f', '--filename', help='filename to be monitored')
@click.option('-d', '--directory', default='.',
                                   help='directory where the file is present')
def cli(filename, directory):
    print('Watching file:', filename)
    wm = pyinotify.WatchManager()
    wm.add_watch(directory, pyinotify.IN_CLOSE_WRITE, rec=True)
    eh = MyEventHandler()
    eh._process = restart(filename)
    eh._filename = filename
    notifier = pyinotify.Notifier(wm, eh)
    notifier.loop()

if __name__ == '__main__':
    cli()