[Chennaipy] Fwd: Chennaipy - Monday Module - 13 Feb 2023

[selvi dct]

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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