text: #!/usr/bin/env python
  
  """ Echo server - reply back with the received message. """
  
  import os
  import signal
  import socket
  import sys
  
  
  def sigusr1_handler(signum, frame):
      print 'signal %s received, exiting ...' % signum
      sys.exit(0)
  
  
  def setup():
      signal.signal(signal.SIGUSR1, sigusr1_handler)
  
  
  def runserver():
      sock = socket.socket()
      sock.bind(('0.0.0.0', int(os.environ.get('PORT', '12345'))))
      sock.listen(10)
  
      while True:
          c, raddr = sock.accept()
          try:
              d = c.recv(4096)
              c.send(d if d else '')
          finally:
              c.close()
  
  
  if "__main__" == __name__:
      setup()
      runserver()
  