cpython/Lib/test/test_signal.py

# Test the signal module
from test_support import verbose
import signal
import os


if verbose:
	x = '-x'
else:
	x = '+x'
pid = os.getpid()

# Shell script that will send us asynchronous signals
script = """
 (
	set %(x)s
	sleep 2
	kill -5 %(pid)d
	sleep 2
	kill -2 %(pid)d
	sleep 2
	kill -3 %(pid)d
 ) &
""" % vars()

def handlerA(*args):
	if verbose:
		print "handlerA", args

HandlerBCalled = "HandlerBCalled"	# Exception

def handlerB(*args):
	if verbose:
		print "handlerB", args
	raise HandlerBCalled, args

signal.alarm(20)			# Entire test lasts at most 20 sec.
signal.signal(5, handlerA)
signal.signal(2, handlerB)
signal.signal(3, signal.SIG_IGN)
signal.signal(signal.SIGALRM, signal.default_int_handler)

os.system(script)

print "starting pause() loop..."

try:
	while 1:
		if verbose:
			print "call pause()..."
		try:
			signal.pause()
			if verbose:
				print "pause() returned"
		except HandlerBCalled:
			if verbose:
				print "HandlerBCalled exception caught"
			else:
				pass
				
except KeyboardInterrupt:
	if verbose:
		print "KeyboardInterrupt (assume the alarm() went off)"