NAME

signal — signal facilities

DESCRIPTION

The <signal.h> header file defines the following signals:

Value	Name	Default Action	Description
1	SIGHUP	terminate process	terminal line hangup
2	SIGINT	terminate process	interrupt program
3	SIGQUIT	create core image	quit program
4	SIGILL	create core image	illegal instruction
5	SIGTRAP	create core image	trace trap
6	SIGABRT	create core image	abort(3) call (formerly SIGIOT)
7	SIGEMT	create core image	emulate instruction executed
8	SIGFPE	create core image	floating-point exception
9	SIGKILL	terminate process	kill program (cannot be caught or ignored)
10	SIGBUS	create core image	bus error
11	SIGSEGV	create core image	segmentation violation
12	SIGSYS	create core image	invalid system call argument
13	SIGPIPE	terminate process	write to a pipe with no reader
14	SIGALRM	terminate process	real-time timer expired
15	SIGTERM	terminate process	software termination signal
16	SIGURG	discard signal	urgent condition present on socket
17	SIGSTOP	stop process	stop (cannot be caught or ignored)
18	SIGTSTP	stop process	stop signal generated from keyboard
19	SIGCONT	discard signal	continue after stop (even if blocked or ignored)
20	SIGCHLD	discard signal	child status has changed
21	SIGTTIN	stop process	background read attempted from control terminal
22	SIGTTOU	stop process	background write attempted to control terminal
23	SIGIO	discard signal	I/O is possible on a descriptor (see fcntl(2))
24	SIGXCPU	terminate process	CPU time limit exceeded (see setrlimit(2))
25	SIGXFSZ	terminate process	file size limit exceeded (see setrlimit(2))
26	SIGVTALRM	terminate process	virtual time alarm (see setitimer(2))
27	SIGPROF	terminate process	profiling timer alarm (see setitimer(2))
28	SIGWINCH	discard signal	window size change
29	SIGINFO	discard signal	status request from keyboard
30	SIGUSR1	terminate process	user-defined signal 1
31	SIGUSR2	terminate process	user-defined signal 2
32	SIGPWR	discard signal	power failure/restart

A function that is async-signal-safe is either reentrant or non-interruptible by signals. This means that they can be used in signal handlers and in the child of threaded programs after doing fork(2).

The following functions are async-signal-safe. Any function not listed below is unsafe to use in signal handlers.

_Exit(2), _exit(2), abort(3), accept(2), access(2), alarm(3), bind(2), cfgetispeed(3), cfgetospeed(3), cfsetispeed(3), cfsetospeed(3), chdir(2), chmod(2), chown(2), clock_gettime(2), close(2), connect(2), creat(3), dup(2), dup2(2), execle(3), execve(2), fchmod(2), fchown(2), fcntl(2), fdatasync(2), fork(2), fpathconf(2), fstat(2), fsync(2), ftruncate(2), getegid(2), geteuid(2), getgid(2), getgroups(2), getpeername(2), getpgrp(2), getpid(2), getppid(2), getsockname(2), getsockopt(2), getuid(2), kill(2), link(2), listen(2), lseek(2), lstat(2), mkdir(2), mkfifo(2), open(2), pathconf(2), pause(3), pipe(2), poll(2), pthread_mutex_unlock(3), raise(3), read(2), readlink(2), recv(2), recvfrom(2), recvmsg(2), rename(2), rmdir(2), select(2), sem_post(3), send(2), sendmsg(2), sendto(2), setgid(2), setpgid(2), setsid(2), setsockopt(2), setuid(2), shutdown(2), sigaction(2), sigaddset(3), sigdelset(3), sigemptyset(3), sigfillset(3), sigismember(3), sleep(3), signal(3), sigpause(3), sigpending(2), sigprocmask(2), sigset(3), sigsuspend(2), sockatmark(3), socket(2), socketpair(2), stat(2), symlink(2), sysconf(3), tcdrain(3), tcflow(3), tcflush(3), tcgetattr(3), tcgetpgrp(3), tcsendbreak(3), tcsetattr(3), tcsetpgrp(3), time(3), timer_getoverrun(2), timer_gettime(2), timer_settime(2), times(3), umask(2), uname(3), unlink(2), utime(3), wait(2), waitpid(2), write(2).

SEE ALSO

kill(1), kill(2), ptrace(2), sigaction(2), sigaltstack(2), sigprocmask(2), sigstack(2), sigsuspend(2), fpgetmask(3), fpsetmask(3), setjmp(3), sigblock(3), siginterrupt(3), signal(3), sigpause(3), sigsetmask(3), sigsetops(3), tty(4)

STANDARDS

These signals conform to IEEE Std 1003.1-1990 (“POSIX.1”), with the exception of SIGTRAP, SIGEMT, SIGBUS, SIGSYS, SIGURG, SIGIO, SIGXCPU, SIGXFSZ, SIGVTALRM, SIGPROF, SIGWINCH, and SIGINFO which are Berkeley extensions (available on most BSD-derived systems), and SIGPWR which comes from System V.

HISTORY

SIGPWR was introduced in NetBSD 1.4.

NOTES

The current NetBSD kernel never generates the SIGPWR signal.