alertme.py

#!/usr/bin/env python3

import sys, os

def alert():
    os.system('say -v Tessa "Your task has been completed."')

def alert_on_pipe_close():
    try:
        while True:
            text = sys.stdin.read()
            if text == '':
                sys.stdout.flush()
                break
            sys.stdout.write(text)
    finally:
        alert()

if __name__ == '__main__':
    alert_on_pipe_close()