How do I write a unix filter in python?

Question

I want to write a program that reads stdin (unbuffered) and writes stdout (unbuffered) doing some trivial char-by-char transformation. For the sake of the example let\'s say

Answer 1

Read from sys.stdin and write to sys.stdout (or use print). Your example program:

import sys

for line in sys.stdin:
    print line.replace("x", ""),

There isn't a standard way to make stdin unbuffered, and you don't want that. Let the OS buffer it.