Question

I am trying to grab the stdout from airodump-ng using subprocess with no luck.
I think my code causes a deadlock.

   airodump = subprocess.Popen(['airodump-ng','mon0'],stdin=subprocess.PIPE,
                              stdout=subprocess.PIPE,
                              stderr=subprocess.PIPE)

    # wait for 15 seconds to find all networks
    time.sleep(15)

    # save the output
    o_airodump = airodump.stdout.read()
    os.kill(airodump.pid, signal.SIGKILL)
    # airodump.terminate
    print(o_airodump)

How to avoid this problem. Cant think one clean solution.

Answer 1

Don’t sleep and wait (that will just cause airodump to block on a full pipe buffer) and don’t use an unbounded read(). The communicate() method does what you need:

o_airodump, unused_stderr = airodump.communicate(timeout=15)
airodump.kill()

Note: The timeout parameter on communicate was introduced in Python 3.3 which isn’t quite out yet. 😉