subprocess.Popen.stdout - reading stdout in real-time (again)

Question

Again, the same question.
The reason is - I still can\'t make it work after reading the following:

• Real-time intercepting of stdout from another process in

Answer 1

Your particular example doesn't require "real-time" interaction. The following works:

from subprocess import Popen, PIPE

p = Popen(["./a.out"], stdin=PIPE, stdout=PIPE)
output = p.communicate(b"12345")[0] # send input/read all output
print output,

where a.out is your example C program.

In general, for a dialog-based interaction with a subprocess you could use pexpect module (or its analogs on Windows):

import pexpect

child = pexpect.spawn("./a.out")
child.expect("input>>")
child.sendline("12345.67890") # send a number
child.expect(r"\d+\.\d+") # expect the number at the end
print float(child.after) # assert that we can parse it
child.close()