206 lines
5.3 KiB
Groff
206 lines
5.3 KiB
Groff
.\" $NetBSD: nanosleep.2,v 1.23 2016/11/14 10:40:59 wiz Exp $
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.\"
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.\" Copyright (c) 1986, 1991, 1993
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.\" The Regents of the University of California. 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, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)sleep.3 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd October 7, 2021
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.Dt NANOSLEEP 2
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.Os
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.Sh NAME
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.Nm nanosleep
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.Nd high resolution sleep
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In time.h
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.Ft int
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.Fo clock_nanosleep
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.Fa "clockid_t clock_id"
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.Fa "int flags"
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.Fa "const struct timespec *rqtp"
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.Fa "struct timespec *rmtp"
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.Fc
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.Ft int
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.Fo nanosleep
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.Fa "const struct timespec *rqtp"
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.Fa "struct timespec *rmtp"
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.Fc
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.Sh DESCRIPTION
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If the
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.Dv TIMER_ABSTIME
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flag is not set in the
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.Fa flags
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argument, then
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.Fn clock_nanosleep
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suspends execution of the calling thread until either the
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time interval specified by the
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.Fa rqtp
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argument has elapsed,
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or a signal is delivered to the calling process and its
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action is to invoke a signal-catching function or to terminate the
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process.
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The clock used to measure the time is specified by the
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.Fa clock_id
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argument.
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.Pp
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If the
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.Dv TIMER_ABSTIME
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flag is set in the
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.Fa flags
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argument, then
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.Fn clock_nanosleep
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suspends execution of the calling thread until either the value
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of the clock specified by the
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.Fa clock_id
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argument reaches the absolute time specified by the
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.Fa rqtp
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argument,
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or a signal is delivered to the calling process and its
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action is to invoke a signal-catching function or to terminate the
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process.
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If, at the time of the call, the time value specified by
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.Fa rqtp
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is less than or equal to the time value of the specified clock, then
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.Fn clock_nanosleep
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returns immediately and the calling thread is not suspended.
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.Pp
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The suspension time may be longer than requested due to the
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scheduling of other activity by the system.
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It is also subject to the allowed time interval deviation
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specified by the
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.Va kern.timecounter.alloweddeviation
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.Xr sysctl 8
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variable.
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An unmasked signal will terminate the sleep early, regardless of the
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.Dv SA_RESTART
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value on the interrupting signal.
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The
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.Fa rqtp
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and
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.Fa rmtp
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arguments can point to the same object.
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.Pp
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The following
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.Fa clock_id
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values are supported:
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.Pp
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.Bl -item -compact -offset indent
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.It
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CLOCK_MONOTONIC
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.It
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CLOCK_MONOTONIC_FAST
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.It
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CLOCK_MONOTONIC_PRECISE
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.It
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CLOCK_REALTIME
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.It
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CLOCK_REALTIME_FAST
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.It
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CLOCK_REALTIME_PRECISE
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.It
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CLOCK_SECOND
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.It
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CLOCK_UPTIME
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.It
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CLOCK_UPTIME_FAST
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.It
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CLOCK_UPTIME_PRECISE
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.El
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.Pp
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The
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.Fn nanosleep
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function behaves like
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.Fn clock_nanosleep
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with a
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.Fa clock_id
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argument of
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.Dv CLOCK_REALTIME
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and without the
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.Dv TIMER_ABSTIME
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flag in the
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.Fa flags
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argument.
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.Sh RETURN VALUES
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These functions return zero when the requested time has elapsed.
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.Pp
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If these functions return for any other reason, then
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.Fn clock_nanosleep
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will directly return the error number, and
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.Fn nanosleep
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will return \-1 with the global variable
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.Va errno
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set to indicate the error.
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If a relative sleep is interrupted by a signal and
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.Fa rmtp
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is
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.Pf non- Dv NULL ,
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the timespec structure it references is updated to contain the
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unslept amount (the request time minus the time actually slept).
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.Sh ERRORS
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These functions can fail with the following errors.
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.Bl -tag -width Er
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.It Bq Er EFAULT
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Either
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.Fa rqtp
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or
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.Fa rmtp
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points to memory that is not a valid part of the process
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address space.
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.It Bq Er EINTR
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The function was interrupted by the delivery of a signal.
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.It Bq Er EINVAL
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The
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.Fa rqtp
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argument specified a nanosecond value less than zero
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or greater than or equal to 1000 million.
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.It Bq Er EINVAL
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The
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.Fa flags
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argument contained an invalid flag.
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.It Bq Er EINVAL
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The
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.Fa clock_id
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argument was
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.Dv CLOCK_THREAD_CPUTIME_ID
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or an unrecognized value.
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.It Bq Er ENOTSUP
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The
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.Fa clock_id
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argument was valid but not supported by this implementation of
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.Fn clock_nanosleep .
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.El
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.Sh SEE ALSO
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.Xr clock_gettime 2 ,
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.Xr sigaction 2 ,
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.Xr sleep 3
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.Sh STANDARDS
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These functions conform to
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.St -p1003.1-2008 .
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