Python capture subprocess output after termination

Question

I am trying to get subprocess output (on Windows) at the time the TimeoutExpired exception is raised. Any ideas?

try:
    proc = subprocess.run(cmd,timeout=3)
except subprocess.TimeoutExpired:
    print(???)

Answer 1

You need to use Popen and subprocess.PIPE in order to catch the process output when timeout expires. In particular Popen.communicate is what you need. Here is an example

proc = subprocess.Popen(["ping", "192.168.1.1"],
                        stdout=subprocess.PIPE)

try:
    output, error = proc.communicate(timeout=2)
except subprocess.TimeoutExpired:
    proc.kill()
    output, error = proc.communicate()
    print(output)
    print(error)

This will print the process output up to the time out expiration.