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.\" Copyright (c) 1983, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
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.\" notice, this list of conditions and the following disclaimer.
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.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
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.\" SUCH DAMAGE.
.\"
.\" @(#)sigsuspend.2 8.2 (Berkeley) 5/16/95
.\" $FreeBSD$
.\"
.Dd May 16, 1995
.Dt SIGSUSPEND 2
.Os
.Sh NAME
.Nm sigsuspend
.Nd atomically release blocked signals and wait for interrupt
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In signal.h
.Ft int
.Fn sigsuspend "const sigset_t *sigmask"
.Sh DESCRIPTION
The
.Fn sigsuspend
system call
temporarily changes the blocked signal mask to the set to which
.Fa sigmask
points,
and then waits for a signal to arrive;
on return the previous set of masked signals is restored.
The signal mask set
is usually empty to indicate that all
signals are to be unblocked for the duration of the call.
.Pp
In normal usage, a signal is blocked using
.Xr sigprocmask 2
to begin a critical section, variables modified on the occurrence
of the signal are examined to determine that there is no work
to be done, and the process pauses awaiting work by using
.Fn sigsuspend
with the previous mask returned by
.Xr sigprocmask .
.Sh RETURN VALUES
The
.Fn sigsuspend
system call
always terminates by being interrupted, returning -1 with
.Va errno
set to
.Er EINTR .
.Sh SEE ALSO
.Xr sigaction 2 ,
.Xr sigprocmask 2 ,
.Xr sigsetops 3
.Sh STANDARDS
The
.Fn sigsuspend
system call is expected to conform to
.St -p1003.1-90 .
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