Date: 13 Feb 2023
Module : signal
Installation : Default Python Module
About:
Signals are an operating system feature that provide a means of notifying
your program of an event, and having it handled asynchronously. They can be
generated by the system itself, or sent from one process to another. Since
signals interrupt the regular flow of your program, it is possible that
some operations (especially I/O) may produce error if a signal is received
in the middle.
Sample:
import signal
def alarm_received(n, stack):
return
signal.signal(signal.SIGALRM, alarm_received)
signals_to_names = {}
for n in dir(signal):
if n.startswith('SIG') and not n.startswith('SIG_'):
signals_to_names[getattr(signal, n)] = n
for s, name in sorted(signals_to_names.items()):
handler = signal.getsignal(s)
if handler is signal.SIG_DFL:
handler = 'SIG_DFL'
elif handler is signal.SIG_IGN:
handler = 'SIG_IGN'
print('%-10s (%2d):' % (name, s), handler)
Output:
SIGHUP ( 1): SIG_DFL
SIGINT ( 2): <built-in function default_int_handler>
SIGQUIT ( 3): SIG_DFL
SIGILL ( 4): SIG_DFL
SIGTRAP ( 5): SIG_DFL
SIGIOT ( 6): SIG_DFL
SIGEMT ( 7): SIG_DFL
SIGFPE ( 8): SIG_DFL
SIGKILL ( 9): None
SIGBUS (10): SIG_DFL
SIGSEGV (11): SIG_DFL
SIGSYS (12): SIG_DFL
SIGPIPE (13): SIG_IGN
SIGALRM (14): <function alarm_received at 0x7fb2926bb160>
SIGTERM (15): SIG_DFL
SIGURG (16): SIG_DFL
SIGSTOP (17): None
SIGTSTP (18): SIG_DFL
SIGCONT (19): SIG_DFL
SIGCHLD (20): SIG_DFL
SIGTTIN (21): SIG_DFL
SIGTTOU (22): SIG_DFL
SIGIO (23): SIG_DFL
SIGXCPU (24): SIG_DFL
SIGXFSZ (25): SIG_IGN
SIGVTALRM (26): SIG_DFL
SIGPROF (27): SIG_DFL
SIGWINCH (28): SIG_DFL
SIGINFO (29): SIG_DFL
SIGUSR1 (30): SIG_DFL
SIGUSR2 (31): SIG_DFL
Reference:
https://docs.python.org/3/library/signal.html
https://pymotw.com/2/signal/
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