replace.py

#!/usr/bin/python
# -*- coding: utf-8 -*-
import glob
from tempfile import mkstemp
from shutil import move
from os import remove, close
import re

def replace(file_path, pattern, subst):
    fh, abs_path = mkstemp()
    with open(abs_path, 'w') as new_file:
        with open(file_path) as old_file:
            new_file.write(re.sub(pattern, subst, old_file.read()))
    close(fh)
    remove(file_path)
    move(abs_path, file_path)