live output from subprocess command

Question

I\'m using a python script as a driver for a hydrodynamics code. When it comes time to run the simulation, I use subprocess.Popen to run the code, collect the

Answer 1

Based on all the above I suggest a slightly modified version (python3):

• while loop calling readline (The iter solution suggested seemed to block forever for me - Python 3, Windows 7)
• structered so handling of read data does not need to be duplicated after poll returns not-None
• stderr piped into stdout so both output outputs are read
• Added code to get exit value of cmd.

Code:

import subprocess
proc = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE,
                        stderr=subprocess.STDOUT, universal_newlines=True)
while True:
    rd = proc.stdout.readline()
    print(rd, end='')  # and whatever you want to do...
    if not rd:  # EOF
        returncode = proc.poll()
        if returncode is not None:
            break
        time.sleep(0.1)  # cmd closed stdout, but not exited yet

# You may want to check on ReturnCode here