the unix end boss is hard

pgrpfun.py

import os
import pty
import signal
import sys
import subprocess
import time


def am_i_foreground():
    if os.tcgetpgrp(0) == os.getpgrp():
        return 'foreground'
    else:
        return 'background'


master, slave = pty.openpty()
p = subprocess.Popen(['sh'], stdin=slave, stdout=slave, stderr=slave)
print('subshell started', am_i_foreground())
time.sleep(0.1)
print('subshell running', am_i_foreground())
if '-k' in sys.argv[1:]:
    os.kill(p.pid, signal.SIGKILL)
else:
    os.close(master)
p.wait()
print('subshell exited status', p.returncode, am_i_foreground())
time.sleep(1.0)
print('after waiting', am_i_foreground())

wtf.txt

mwhudson@anduril:~/src$ python3 pgrpfun.py 
subshell started foreground
subshell running background
subshell exited status 0 foreground
after waiting foreground
mwhudson@anduril:~/src$ python3 pgrpfun.py -k
subshell started foreground
subshell running background
subshell exited status -9 background
after waiting background