Example of signal mask inheritance using python-signalfd package

sigprocmask.py

from __future__ import print_function
import signal
import signalfd
import sys 
import threading

def report():
    mask = signalfd.sigprocmask(signalfd.SIG_BLOCK, []) 
    print('- pid: %s thread: %s mask: %s' % ( 
          os.getpid(), threading.current_thread(), mask))

print('parent starting pid: %s' % os.getpid())

signalfd.sigprocmask(signalfd.SIG_BLOCK, [signal.SIGTERM, signal.SIGINT, signal.SIGHUP])

report()

print('starting a thread in parent...')

threading.Thread(target=report).start()

pid = os.fork()
if pid:
    os.waitpid(pid, 0)
else:
    print('child starting pid: %s...' % os.getpid())
    report()

    print('starting a thread in child...')
    threading.Thread(target=report).start()

    pid = os.fork()
    if pid:
        os.waitpid(pid, 0)
    else:
        print('subchild starting pid: %s...' % os.getpid())
        report()

        print('starting a thread in sub child...')
        threading.Thread(target=report).start()