A non-blocking read on a subprocess.PIPE in Python

Question

I\'m using the subprocess module to start a subprocess and connect to its output stream (standard output). I want to be able to execute non-blocking reads on its standard ou

Answer 1

I add this problem to read some subprocess.Popen stdout. Here is my non blocking read solution:

import fcntl

def non_block_read(output):
    fd = output.fileno()
    fl = fcntl.fcntl(fd, fcntl.F_GETFL)
    fcntl.fcntl(fd, fcntl.F_SETFL, fl | os.O_NONBLOCK)
    try:
        return output.read()
    except:
        return ""

# Use example
from subprocess import *
sb = Popen("echo test && sleep 1000", shell=True, stdout=PIPE)
sb.kill()

# sb.stdout.read() # <-- This will block
non_block_read(sb.stdout)
'test\n'