How do I check if stdin has some data?

I've been using

if not sys.stdin.isatty()

Here's an example:

import sys

def main():
    if not sys.stdin.isatty():
        print "not sys.stdin.isatty"
    else:
        print "is  sys.stdin.isatty"

Running

$ echo "asdf" | stdin.py
not sys.stdin.isatty

sys.stdin.isatty() returns false if stdin is not connected to an interactive input device (e.g. a tty).

isatty(...)
    isatty() -> true or false. True if the file is connected to a tty device.

On Unix systems you can do the following:

import sys
import select

if select.select([sys.stdin, ], [], [], 0.0)[0]:
    print("Have data!")
else:
    print("No data")

On Windows the select module may only be used with sockets though so you'd need to use an alternative mechanism.

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