105 lines
3.1 KiB
Groff
105 lines
3.1 KiB
Groff
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.\" $NetBSD: usleep.3,v 1.19 2010/04/29 17:29:56 jruoho 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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.\" @(#)usleep.3 8.1 (Berkeley) 6/4/93
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.\"
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.Dd April 29, 2010
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.Dt USLEEP 3
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.Os
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.Sh NAME
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.Nm usleep
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.Nd suspend execution for interval of microseconds
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In unistd.h
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.Ft int
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.Fn usleep "useconds_t microseconds"
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.Sh DESCRIPTION
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The
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.Fn usleep
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function
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suspends execution of the calling process
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until either the number of microseconds specified by
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.Fa microseconds
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have elapsed 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 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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.Pp
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The
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.Fa microseconds
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argument must be less than 1,000,000.
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If the value of
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.Fa microseconds
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is 0, then the call has no effect.
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.Sh RETURN VALUES
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On successful completion,
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.Fn usleep
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returns 0.
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Otherwise, it returns \-1 and sets
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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 usleep
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function may 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 microseconds
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interval specified 1,000,000 or more microseconds.
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.El
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.Sh SEE ALSO
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.Xr nanosleep 2 ,
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.Xr sleep 3
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.Sh STANDARDS
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The
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.Fn usleep
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function conforms to
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.St -xpg4.2 .
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It later appeared in the
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.Tn POSIX
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standard, but in
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.St -p1003.1-2004
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it was marked as legacy and the use of
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.Xr nanosleep 2
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was recommended instead.
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The
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.St -p1003.1-2008
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revision removed
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.Fn usleep
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from the specification.
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.Sh HISTORY
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The
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.Fn usleep
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function appeared in
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.Bx 4.3 .
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