How to read the first byte of a subprocess's stdout and then discard the rest in Python?

Question

I\'d like to read the first byte of a subprocess\' stdout to know that it has started running. After that I\'d like to discard all further output, so that I don\'t have to w

Answer 1

If you're using Python 3.3+, you can use the DEVNULL special value for stdout and stderr to discard subprocess output.

from subprocess import Popen, DEVNULL

process = Popen(["mycmd", "myarg"], stdout=DEVNULL, stderr=DEVNULL)

Or if you're using Python 2.4+, you can simulate this with:

import os
from subprocess import Popen

DEVNULL = open(os.devnull, 'wb')
process = Popen(["mycmd", "myarg"], stdout=DEVNULL, stderr=DEVNULL)

However this doesn't give you the opportunity to read the first byte of stdout.