Simple Python autoreload script

autoreload.py

import os, sys, subprocess, signal, binascii, time

"""
Usage:
   $ python autoreload.py app.py
"""

last_crc32 = 0
terminate = False

def signal_handler(signum, frame):
    global terminate
    terminate = True
    print('CTRL+C has interrupt auto reloading')


def main():
    if len(sys.argv) != 2:
        print('Please pass an script argument!')
        exit(-1)

    script = sys.argv[1]
    if not os.path.isfile(script):
        print('Script file is not a file or exist')
        exit(-2)

    global last_crc32, terminate

    process = None

    while not terminate:

        script_content = open(script).read().encode()
        current_crc32 = binascii.crc32(script_content)

        if last_crc32 != current_crc32:
            last_crc32 = current_crc32

            if process is not None:
                pid = process.pid
                print('Killing PID:', pid)
                os.kill(pid, signal.SIGINT)
                process = None

            print('Auto reloading script: ', script)
            process = subprocess.Popen(['python', script], shell=False)
            print('Reloaded on PID:', process.pid)

        time.sleep(1.0)

    if process is not None:
        os.kill(process.pid, signal.SIGINT)

    print('Exiting ...')
    sys.exit(0)


if __name__ == '__main__':
    signal.signal(signal.SIGINT, signal_handler)
    main()