1 import subprocess
  2 import time
  3 import sys
  4 import errno
  5 import os
  6 import fcntl
  7 import signal
  8
  9 def unblock_stdout():
 10   # get a non-blocking stdout
 11   child_pid, child_pty = os.forkpty()
 12   if child_pid != 0: # parent
 13
 14     # child is in its own process group, manually pass kill signals
 15     signal.signal(signal.SIGINT, lambda signum, frame: os.kill(child_pid, signal.SIGINT))
 16     signal.signal(signal.SIGTERM, lambda signum, frame: os.kill(child_pid, signal.SIGTERM))
 17
 18     fcntl.fcntl(sys.stdout, fcntl.F_SETFL,
 19        fcntl.fcntl(sys.stdout, fcntl.F_GETFL) | os.O_NONBLOCK)
 20
 21     while True:
 22       try:
 23         dat = os.read(child_pty, 4096)
 24       except OSError as e:
 25         if e.errno == errno.EIO:
 26           break
 27         continue
 28
 29       if not dat:
 30         break
 31
 32       try:
 33         sys.stdout.write(dat.decode('utf8'))
 34       except (OSError, IOError):
 35         pass
 36
 37     os._exit(os.wait()[1])
 38
 39 unblock_stdout()
 40 subprocess.Popen(["python", "run.py"],
 41                  preexec_fn=os.setpgrp)
 42 while 1:
 43   time.sleep(1)
 44