How do you read from stdin?

Question

I\'m trying to do some of the code golf challenges, but they all require the input to be taken from stdin. How do I get that in Python?

Answer 1

Building on all the anwers using sys.stdin, you can also do something like the following to read from an argument file if at least one argument exists, and fall back to stdin otherwise:

import sys
f = open(sys.argv[1]) if len(sys.argv) > 1 else sys.stdin    
for line in f:
#     Do your stuff

and use it as either

$ python do-my-stuff.py infile.txt

or

$ cat infile.txt | python do-my-stuff.py

or even

$ python do-my-stuff.py < infile.txt

That would make your Python script behave like many GNU/Unix programs such as cat, grep and sed.