old_contents: 
  # -*- coding: utf-8 -*-
  ## Author : github.com/jeonghoonkang
  
  import serial,os,time
  import sys
  import fcntl, socket, struct
  
  lineCnt = 0
  
  def getHwAddr(ifname):
  	s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
  	info = fcntl.ioctl(s.fileno(), 0x8927, struct.pack('256s', ifname[:15]))
  	return ':'.join(['%02x' %ord(char) for char in info[18:24]])
  
  def init():
      macAddr = getHwAddr('eth0')
      macAddr = macAddr.replace(':','.')
      print " # eth0 HW MAC addr is " + macAddr
  
  if __name__== "__main__" :
  
      if len(sys.argv) is 1:
          print " # RaspberryPi2 SW "
          print " # Serial Byte read and print "
          print " # Default serial device is /dev/ttyAMA0 "
          print " # example : python serial_byte.py 115200 "
          exit(1)
  
      init()
      rate = sys.argv[1]
  
      try:
          # open RASPI serial device, 38400
          # Check speed 38400 or 115200, 9800
          serial_in_device = serial.Serial('/dev/ttyAMA0', rate)
      except serial.SerialException, e:
          print " << Serial open error"
          exit(1)
      print " >> Serial Open Complete "
  
      while True:
          lineCnt += 1
          try:
              in_byte = serial_in_device.read(1) 
              print " [cnt: %3d] " %lineCnt, (in_byte)
          except serial.SerialException, e:
              print e
              print " [cnt: %3d]" %lineCnt, " << Serial read error"
              exit(0)
  
  
new_contents: 
  # -*- coding: utf-8 -*-
  # Author : Jeonghoonkang, github.com/jeonghoonkang
  
  import serial,os,time
  import sys
  import fcntl, socket, struct
  
  lineCnt = 0
  
  def getHwAddr(ifname):
  	s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
  	info = fcntl.ioctl(s.fileno(), 0x8927, struct.pack('256s', ifname[:15]))
  	return ':'.join(['%02x' %ord(char) for char in info[18:24]])
  
  def init():
      macAddr = getHwAddr('eth0')
      macAddr = macAddr.replace(':','.')
      print " # eth0 HW MAC addr is " + macAddr
  
  if __name__== "__main__" :
  
      if len(sys.argv) is 1:
          print " # RaspberryPi2 SW "
          print " # Serial Byte read and print "
          print " # Default serial device is /dev/ttyAMA0 "
          print " # example : python serial_byte.py 115200 "
          exit(1)
  
      init()
      rate = sys.argv[1]
  
      try:
          # open RASPI serial device, 38400
          # Check speed 38400 or 115200, 9800
          serial_in_device = serial.Serial('/dev/ttyAMA0', rate)
      except serial.SerialException, e:
          print " << Serial open error"
          exit(1)
      print " >> Serial Open Complete "
  
      while True:
          lineCnt += 1
          try:
              in_byte = serial_in_device.read(1) 
              print " [cnt: %3d] " %lineCnt, (in_byte)
          except serial.SerialException, e:
              print e
              print " [cnt: %3d]" %lineCnt, " << Serial read error"
              exit(0)
  
  
subject: Update serial_byte.py