207 lines
5.2 KiB
Groff
207 lines
5.2 KiB
Groff
.\" Copyright (c) 2005 David Xu <davidxu@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice(s), this list of conditions and the following disclaimer as
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.\" the first lines of this file unmodified other than the possible
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.\" addition of one or more copyright notices.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice(s), this list of conditions and the following disclaimer in
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.\" the documentation and/or other materials provided with the
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.\" distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
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.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd September 27, 2012
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.Dt SIGTIMEDWAIT 2
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.Os
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.Sh NAME
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.Nm sigtimedwait , sigwaitinfo
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.Nd "wait for queued signals (REALTIME)"
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In signal.h
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.Ft int
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.Fo sigtimedwait
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.Fa "const sigset_t *restrict set" "siginfo_t *restrict info"
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.Fa "const struct timespec *restrict timeout"
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.Fc
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.Ft int
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.Fn sigwaitinfo "const sigset_t * restrict set" "siginfo_t * restrict info"
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.Sh DESCRIPTION
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The
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.Fn sigtimedwait
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system call is equivalent to
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.Fn sigwaitinfo
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except that if none of the signals specified by
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.Fa set
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are pending,
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.Fn sigtimedwait
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waits for the time interval specified in the
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.Vt timespec
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structure referenced by
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.Fa timeout .
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If the
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.Vt timespec
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structure pointed to by
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.Fa timeout
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is zero-valued and if none of the signals specified by
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.Fa set
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are pending, then
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.Fn sigtimedwait
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returns immediately with an error.
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If
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.Fa timeout
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is the
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.Dv NULL
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pointer, the behavior is unspecified.
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.Dv CLOCK_MONOTONIC
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clock is used to measure the time interval specified by the
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.Fa timeout
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argument.
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.Pp
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The
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.Fn sigwaitinfo
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system call selects the pending signal from the set specified by
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.Fa set .
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Should any of multiple pending signals in the range
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.Dv SIGRTMIN
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to
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.Dv SIGRTMAX
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be selected, it shall be the lowest numbered one.
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The
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selection order between realtime and non-realtime signals, or
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between multiple pending non-realtime signals, is unspecified.
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If no signal in
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.Fa set
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is pending at the time of the call, the calling thread
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is suspended until one or more signals in
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.Fa set
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become pending or until it is interrupted by an unblocked, caught signal.
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.Pp
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The
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.Fn sigwaitinfo
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system call is equivalent to the
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.Fn sigwait
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system call if the
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.Fa info
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argument is
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.Dv NULL .
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If the
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.Fa info
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argument is
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.Pf non- Dv NULL ,
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the
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.Fn sigwaitinfo
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function is equivalent to
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.Fn sigwait ,
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except that the selected signal number shall be stored in the
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.Va si_signo
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member, and the cause of the signal shall be stored in the
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.Va si_code
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member.
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Besides this, the
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.Fn sigwaitinfo
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and
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.Fn sigtimedwait
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system calls may return
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.Er EINTR
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if interrupted by signal, which is not allowed for the
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.Fn sigwait
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function.
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.Pp
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If any value is queued to the selected signal, the first such queued
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value is dequeued and, if the info argument is
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.Pf non- Dv NULL ,
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the value is stored in the
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.Va si_value
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member of
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.Fa info .
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The system resource used to queue the signal
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is released and returned to the system for other use.
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If no value is queued,
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the content of the
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.Va si_value
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member is zero-valued.
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If no further signals are
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queued for the selected signal, the pending indication for that signal
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is reset.
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.Sh RETURN VALUES
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Upon successful completion (that is, one of the signals specified by
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.Fa set
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is pending or is generated)
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.Fn sigwaitinfo
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and
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.Fn sigtimedwait
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return the selected signal number.
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Otherwise, the functions return a value of \-1
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and set the global variable
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.Va errno
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to indicate the error.
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.Sh ERRORS
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The
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.Fn sigtimedwait
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system call
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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No signal specified by set was generated within the specified timeout period.
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.El
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.Pp
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The
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.Fn sigtimedwait
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and
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.Fn sigwaitinfo
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system calls fail if:
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.Bl -tag -width Er
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.It Bq Er EINTR
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The wait was interrupted by an unblocked, caught signal.
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.El
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.Pp
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The
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.Fn sigtimedwait
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system call may also fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The
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.Fa timeout
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argument specified a
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.Va tv_nsec
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value less than zero or greater than or equal
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to 1000 million.
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Kernel only checks for this error if no signal is pending in set and it
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is necessary to wait.
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.El
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.Sh SEE ALSO
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.Xr sigaction 2 ,
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.Xr sigpending 2 ,
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.Xr sigqueue 2 ,
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.Xr sigsuspend 2 ,
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.Xr sigwait 2 ,
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.Xr pause 3 ,
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.Xr pthread_sigmask 3 ,
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.Xr siginfo 3
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.Sh STANDARDS
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The
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.Fn sigtimedwait
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and
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.Fn sigwaitinfo
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system calls conform to
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.St -p1003.1-96 .
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