How to pass SIGINT to child process with Python subprocess.Popen() using shell = true

Question

I am currently trying to write (Python 2.7.3) kind of a wrapper for GDB, which will allow me to dynamically switch from scripted input to interactive communication with GDB.

So far I use

self.process = subprocess.Popen(["gdb vuln"], stdin = subprocess.PIPE,  shell = True)

to start gdb within my script. (vuln is the binary I want to examine)

Since a key feature of gdb is to pause the execution of the attached process and allow the user to inspect registers and memory on receiving SIGINT (STRG+C) I do need some way to pass a SIGINT signal to it.

Neither

self.process.send_signal(signal.SIGINT)

nor

os.kill(self.process.pid, signal.SIGINT)

or

os.killpg(self.process.pid, signal.SIGINT)

work for me.

When I use one of these functions there is no response. I suppose this problem arises from the use of shell=True. However, at this point I am really out of ideas. Even my old friend Google couldn't really help me out this time, so maybe you can help me. Thank's in advance.

Cheers, Mike

Answer 1

Here is what worked for me:

import signal
import subprocess

try:
    p = subprocess.Popen(...)
    p.wait()
except KeyboardInterrupt:
    p.send_signal(signal.SIGINT)
    p.wait()