from tempfile import mkstemp

from shutil import move

from os import fdopen, remove

def replace(file_path, pattern, subst):

    #Create temp file

    fh, abs_path = mkstemp()

    with fdopen(fh,'w') as new_file:

        with open(file_path) as old_file:

            for line in old_file:

                new_file.write(line.replace(pattern, subst))

    #Remove original file

    remove(file_path)

    #Move new file

    move(abs_path, file_path)