http://hi.baidu.com/isilencer/item/32d5ae5fabcda88709be17b7

virtual_serial.py

#! /usr/bin/env python

#coding=utf-8

import pty
import os
import select

def mkpty():
#
	master1, slave = pty.openpty()
	slaveName1 = os.ttyname(slave)
	master2, slave = pty.openpty()
	slaveName2 = os.ttyname(slave)
	print '\nslave device names: ', slaveName1, slaveName2
	return master1, master2


if __name__ == "__main__":

	master1, master2 = mkpty()
	while True:
		rl, wl, el = select.select([master1,master2], [], [], 1)
		for master in rl:
			data = os.read(master, 128)
			print "read %d data." % len(data)
			if master==master1:
				os.write(master2, data)
			else:
				os.write(master1, data)