This question is in relation to:
python, subprocess: reading output from subprocess
If P is a subprocess started with a command along the lines of
import subprocess
P = subprocess.Popen ("command", stdout=subprocess.PIPE)
we can read the output P produces by P.stdout.readline (). This is a blocking read though. How can I check if there is output ready for reading (without blocking)?
If you are using *nix, then you can use the select module to poll the stdout file descriptor
import subprocess
import select
poller = select.epoll()
P = subprocess.Popen ("command", stdout=subprocess.PIPE)
poller.register(P.stdout, select.EPOLLHUP)
while True:
#block indefinitely: timeout = -1
#return immediately: timeout = 0
for fd, flags in poller.poll(timeout=0)
foo = P.stdout.readline()
#do something else before the next poll
