Question

I thought this program will echo my console input line by line:

import os, sys

for line in sys.stdin:
    print line

Unfortunately it waits for EOF (Ctrl + D) and then it produces output. How should I modify my program to get output line by line?

Answer 1

Python 2.x:

for line in iter(sys.stdin.readline, ''):
    print line,

Python 3.x:

for line in iter(sys.stdin.readline, ''):
    print(line, end='')

See the documentation on iter() with two arguments, it actually has reading from a file like this as one of the examples.