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SIGWAIT(2)		  FreeBSD System Calls Manual		    SIGWAIT(2)

NAME
     sigwait --	select a set of	signals

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <signal.h>

     int
     sigwait(const sigset_t * restrict set, int	* restrict sig);

DESCRIPTION
     The sigwait() system call selects a set of	signals, specified by set.  If
     none of the selected signals are pending, sigwait() waits until one or
     more of the selected signals has been generated.  Then sigwait() atomi-
     cally clears one of the selected signals from the set of pending signals
     (for the process or for the current thread) and sets the location pointed
     to	by sig to the signal number that was cleared.

     The signals specified by set should be blocked at the time	of the call to
     sigwait().

     If	more than one thread is	using sigwait()	to wait	for the	same signal,
     no	more than one of these threads will return from	sigwait() with the
     signal number.  If	more than a single thread is blocked in	sigwait() for
     a signal when that	signal is generated for	the process, it	is unspecified
     which of the waiting threads returns from sigwait().  If the signal is
     generated for a specific thread, as by pthread_kill(), only that thread
     will return.

     Should any	of the multiple	pending	signals	in the range SIGRTMIN to
     SIGRTMAX be selected, it will be the lowest numbered one.	The selection
     order between realtime and	non-realtime signals, or between multiple
     pending non-realtime signals, is unspecified.

IMPLEMENTATION NOTES
     The sigwait() function is implemented as a	wrapper	around the
     __sys_sigwait() system call, which	retries	the call on EINTR error.

RETURN VALUES
     If	successful, sigwait() returns 0	and sets the location pointed to by
     sig to the	cleared	signal number.	Otherwise, an error number is
     returned.

ERRORS
     The sigwait() system call will fail if:

     [EINVAL]		The set	argument specifies one or more invalid signal
			numbers.

SEE ALSO
     sigaction(2), sigpending(2), sigqueue(2), sigsuspend(2), sigtimedwait(2),
     sigwaitinfo(2), pause(3), pthread_sigmask(3)

STANDARDS
     The sigwait() function conforms to	ISO/IEC	9945-1:1996 (``POSIX.1'').

FreeBSD	10.0		       September 6, 2013		  FreeBSD 10.0

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | IMPLEMENTATION NOTES | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS

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