get unused port

get_unused_port.py

>>> import SocketServer
>>> ss = SocketServer.TCPServer(('localhost', 8080), None)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/SocketServer.py", line 408, in __init__
    self.server_bind()
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/SocketServer.py", line 419, in server_bind
    self.socket.bind(self.server_address)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/socket.py", line 224, in meth
    return getattr(self._sock,name)(*args)
socket.error: [Errno 48] Address already in use

>>> import socket
>>> sock = sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
>>> sock.bind(('localhost', 0))
('127.0.0.1', 65284)
>>> unused_port = _[1]  # 65284
>>> sock.close()
>>> ss = SocketServer.TCPServer(('localhost', unused_port), None)
>>> ss.serve_forever()