its_done.py

#!/usr/bin/env python3
import os

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('message')
parser.add_argument('--start', type=int, help='Pass start timestamp to append run time to notification')
parser.add_argument('--apikey', type=str, help='Pushover API key (can also be implicitly defined as ENV variable in $PUSHOVER_API_KEY)', default=os.getenv('PUSHOVER_API_KEY', ''))
parser.add_argument('--userkey', type=str, help='Pushover user key (can also be implicitly defined as ENV variable in $PUSHOVER_USER_KEY)', default=os.getenv('PUSHOVER_USER_KEY', ''))
args = parser.parse_args()


if args.apikey == "" or args.userkey == "":
    print('error: API key and user key must either be passed as arguments or set in environment variables $PUSHOVER_API_KEY and $PUSHOVER_USER_KEY')
    exit(1)

message = args.message

if args.start != None:
    import time
    import datetime
    now = int(time.time())
    duration = now - args.start
    message += " (run time: {0})".format(datetime.timedelta(seconds=duration))

# you can install chump using pip
from chump import Application

app = Application(args.apikey)
app.is_authenticated
user = app.get_user(args.userkey)
message = user.send_message(message)

usage:

# long_running_command.sh && its_done.py "Your thing is done now."