Cross-platform local IP detection.

ip.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Prints the machine's IP address.
# Inspired by https://stackoverflow.com/a/28950776/4839573. Tested in Linux and MacOS.
import socket
import sys

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
try:
    # Doesn't even have to be reachable.
    s.connect(('10.255.255.255', 1))
    ip = s.getsockname()[0]
except:
    ip = '127.0.0.1'
finally:
    s.close()

sys.stdout.write(ip)