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.\" $FreeBSD: src/lib/libc_r/man/sigwait.3,v 1.2.2.6 2001/12/17 10:08:26 ru Exp $
.Dd July 20, 2016
.Dt SIGWAIT 3
.Os
.Sh NAME
.Nm sigwait
.Nd select a set of signals
.Sh LIBRARY
.Lb libpthread
.Sh SYNOPSIS
.In signal.h
.Ft int
.Fn sigwait "const sigset_t * restrict set" "int * restrict sig"
.Sh DESCRIPTION
The
.Fn sigwait
function selects a set of signals, specified by
.Fa set .
If none of the selected signals are pending,
.Fn sigwait
waits until one or more of the selected signals has been generated.
Then
.Fn sigwait
atomically 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
.Fa sig
to the signal number that was cleared.
.Pp
The signals specified by
.Fa set
should be blocked at the time of the call to
.Fn sigwait .
.Sh RETURN VALUES
If successful,
.Fn sigwait
returns 0 and sets the location pointed to by
.Fa sig
to the cleared signal number.
Otherwise, an error number is returned.
.Sh ERRORS
The
.Fn sigwait
function will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa set
argument specifies one or more invalid signal numbers.
.El
.Sh SEE ALSO
.Xr sigaction 2 ,
.Xr sigpending 2 ,
.Xr sigsuspend 2 ,
.Xr pause 3 ,
.Xr pthread_sigmask 3
.Sh STANDARDS
The
.Fn sigwait
function conforms to
.St -p1003.1-96 .