signal

Interface to OS signals: install handlers, query the current handler, manage masks, schedule alarms. On Windows only a subset is available.

Source-of-record: Modules/signalmodule.c, signal docs.

Handlers

Function	Effect
signal(signum, handler)	Install handler; returns previous handler.
getsignal(signum)	Current handler.
strsignal(signum)	Human-readable name.
valid_signals()	set[int] of signals on this platform.

Special handlers: SIG_DFL (default), SIG_IGN (ignore).

Handlers run between bytecodes in the main thread.

Constants

SIGINT, SIGTERM, SIGHUP, SIGQUIT, SIGKILL, SIGSTOP, SIGCONT, SIGCHLD, SIGPIPE, SIGALRM, SIGUSR1, SIGUSR2, SIGABRT, SIGSEGV, SIGILL, SIGFPE, SIGBUS, SIGWINCH, SIGIO, SIGTRAP, SIGSYS, NSIG.

Masks (POSIX)

Function	Effect
pthread_sigmask(how, mask)	Block / unblock signals on the thread.
pthread_kill(thread_id, signum)	Send signal to a thread.
sigpending()	Set of pending signals.
sigwait(sigset)	Block waiting for a signal.
sigwaitinfo(sigset)	Same, returns struct_siginfo.
sigtimedwait(sigset, timeout)	Timed variant.

how constants: SIG_BLOCK, SIG_UNBLOCK, SIG_SETMASK.

Alarms and timers

Function	Effect
alarm(seconds)	Schedule SIGALRM.
setitimer(which, seconds, interval=0.0)	POSIX timer.
getitimer(which)	Read.

Timer kinds: ITIMER_REAL, ITIMER_VIRTUAL, ITIMER_PROF.

Async wakeup fd

Function	Effect
set_wakeup_fd(fd, *, warn_on_full_buffer=True)	Write signum byte on a signal.

Used by event loops to wake from select/poll on signal delivery.

Cross-platform notes

Limitation
signal() works only in the main thread.
SIGKILL and SIGSTOP cannot be caught.
Windows supports SIGINT, SIGTERM, SIGBREAK, SIGABRT, SIGFPE, SIGILL, SIGSEGV.

Gopy status

Area	State
signal, getsignal, valid_signals	Complete.
Masks and sigwait family	Complete.
alarm, setitimer/getitimer	Complete.
set_wakeup_fd	Complete.

Reference

• CPython 3.14: signal.
• Modules/signalmodule.c.
• module/signal/. gopy port.