replace utility for large files

replacer.py

# -*- coding: utf-8 -*-

import os, codecs, sys

dir = os.getcwd()
file = sys.argv[1]

Dict = [['a', 'b'], ['c', 'd']]

fname = os.path.join(dir, file)
inFile = codecs.open(fname, "r", "utf-8")
outFile = codecs.open(fname + ".new", "w", "utf-8")

for line in inFile:
	for Dictrow in Dict:
		line = line.replace(Dictrow[0], Dictrow[1])
	outFile.write(line)
	print line
inFile.close()
outFile.close()
os.rename(fname + ".new", fname)