How to listen to a Bitcoin transaction?

Does it have to be blockchain.com or can you switch to another wallet like Electrum? I had no success finding anything for the blockchain wallet, but I came across an old thread where someone created an Electrum forwarded script that worked back in 2013. I don't have the skills to go over the code, so I suggest that someone who knows what he is doing checks if this is safe to use and still works:

Quote from: CryptCard on October 18, 2013, 12:38:20 PM

Start

Code:

sudo python  /root/.electrum/forwarder.py --config /root/.electrum/forwarder.conf

./forwarder.conf

Code:

[electrum]
wallet_path = /root/.electrum/electrum.dat
password = 
address = 1DCKtUCFZZCr1wCxwsYkzemQvxrUq8byps
minimum_transaction = 0.11
fee = 0.001

./forwarder.py

Code:

forwarder.py#!/usr/bin/env python

import time, thread, sys, os
import getopt
import Queue
from electrum import Wallet, Interface, WalletVerifier, SimpleConfig, WalletSynchronizer, Commands

try:
    opts, args = getopt.getopt(sys.argv[1:], 'fc:', ["foreground", "config="])
except getopt.GetoptError:
    print 'forwarder.py [-f|--foreground] [-c filename|--config filename]'
    sys.exit(2)

foreground_scanning = False
config_file_path = "forwarder.conf"

for opt, arg in opts:
    if opt in ('-f', '--foreground'):
        foreground_scanning = True
    elif opt in ('-c', '--config'):
        config_file_path = arg

# Load the configuration file with details
import ConfigParser
forwarder_config = ConfigParser.ConfigParser()
forwarder_config.read(config_file_path)

# Load the wallet from the configured location
config_data = {'wallet_path': forwarder_config.get('electrum', 'wallet_path')}
config = SimpleConfig(config_data)
wallet = Wallet(config)

# Retrieve details about transaction sending
target_address = forwarder_config.get('electrum', 'address')
minimum_transaction = float(forwarder_config.get('electrum', 'minimum_transaction'))
fee = float(forwarder_config.get('electrum', 'fee'))

# Construct the remote Electrum interface
interface = Interface(config)
interface.start(wait = True)
interface.send([('server.peers.subscribe', [])])

# Prepare the 'commands' utility object to make operating easy
commands = Commands(wallet, interface)

# Load in the password used to decrypt the signing keys
if forwarder_config.get('electrum', 'password'):
	commands.password = forwarder_config.get('electrum', 'password')

# Prepare a queue as a simple synchronization primitive to decouple update from send
queue = Queue.Queue()

# Global boolean to prevent recursive update/send events and too-early handling
global allow_put
allow_put = False

# Global number indicating the last height transactions were sent from
global last_send_height
last_send_height = 0 

def on_wallet_update():
    global allow_put
    global last_send_height
    if not allow_put:
        return
    if verifier.local_height == last_send_height:
        #print "Last send height == local height: " + str(last_send_height)
        return
    queue.put(True)

# Setup the wallet's interface and hookup the wallet update callback
wallet.interface = interface
interface.register_callback('updated', on_wallet_update)

# Load in the transaction / tree verifier
verifier = WalletVerifier(interface, config)
wallet.set_verifier(verifier)
verifier.start()

# Load in the wallet synchronizer to load in new data
synchronizer = WalletSynchronizer(wallet, config)
synchronizer.start()

def try_send():
    global allow_put
    global last_send_height

    # Collect balance information to determine if we should continue
    balance = commands.getbalance()
    print "Collected updated balance: " + str(balance)
    confirmed = balance.get('confirmed')
    if not confirmed:
        confirmed = 0
    else:
        confirmed = float(confirmed)
    unconfirmed = balance.get('unconfirmed')
    if not unconfirmed:
        unconfirmed = 0
    else:
        unconfirmed = float(unconfirmed)
    print "Total Balance: " + str(confirmed + unconfirmed)
    # Make sure that we have enough to cover the fee.
    # Also make sure that prior unconfirmed items are enough to cover the fee
    # to avoid pending withdrawals being re-spent and causing unnecessary server errors.
    if (confirmed + unconfirmed) >= (minimum_transaction + fee):
        # Store the last_send_height to avoid re-sending while we are waiting for it to get in the queue
        print "Sending %s to %s w/ fee %s" % (confirmed + unconfirmed - fee, target_address, fee)
        last_send_height = verifier.local_height
        #print "New height " + str(last_send_height)

        try:
	    print target_address
	    print confirmed + unconfirmed - fee
	    print fee
            h = commands.payto(target_address, confirmed + unconfirmed - fee - 0.001, fee)
            print "Transaction sent - " + str(h)
        except BaseException as e:
            print "Failed to send transaction: " + str(e)
        except:
            print "Unknown exception occurred"


# Force a full wallet update up front - then enable wallet updates
wallet.update()
allow_put = True

# Perform an initial send try to bootstrap the process
try_send()

# If foreground scanning - use loop w/ Ctrl+C break method
if foreground_scanning:
    try:
        while True:
            ready = queue.get(True, 1000000)
            if not ready:
                continue
            allow_put = False
            try_send()
            allow_put = True
    except KeyboardInterrupt as e:
        print "Ending server"

# Shutdown server objects
verifier.stop()
synchronizer.stop()
interface.stop()

# Due to daemon threads - follow electrum GUI rules for waiting
time.sleep(0.1)
print "terminated"

The script shows sometimes some errors but it does what it should.
All the incoming payments will be forwarded to the address provided in the forwarder.conf.

-> BIG THANKS to harningt

PS: It doesn't work with the latest development version (git 1.9 electrum) as their are some errors with the WalletVerifier function.
Perhaps someone can fix this.