113 lines
3.3 KiB
Groff
113 lines
3.3 KiB
Groff
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.\" $NetBSD: time.3,v 1.15 2010/04/24 01:35:50 dholland Exp $
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.\"
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.\" Copyright (c) 1989, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" the American National Standards Committee X3, on Information
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.\" Processing Systems.
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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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.\" @(#)time.3 8.1 (Berkeley) 6/4/93
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.\"
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.Dd April 23, 2010
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.Dt TIME 3
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.Os
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.Sh NAME
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.Nm time
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.Nd get time of day
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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 time_t
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.Fn time "time_t *tloc"
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.Sh DESCRIPTION
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The
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.Fn time
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function
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returns the value of time in seconds since 0 hours, 0 minutes,
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0 seconds, January 1, 1970, Coordinated Universal Time.
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.Pp
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A copy of the time value may be saved to the area indicated by the
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pointer
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.Fa tloc .
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If
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.Fa tloc
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is a
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.Dv NULL
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pointer, no value is stored.
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.Pp
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Upon successful completion,
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.Fn time
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returns the value of time.
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Otherwise a value of
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.Po
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.Po Fa time_t Pc \-1
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.Pc
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is returned and the global variable
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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The following error codes may be set in
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.Va errno :
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.Bl -tag -width Er
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.It Bq Er EFAULT
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An argument address referenced invalid memory.
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.El
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.Sh SEE ALSO
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.Xr gettimeofday 2 ,
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.Xr ctime 3
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.Sh STANDARDS
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The
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.Fn time
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function conforms to
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.St -p1003.1-90 .
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.Sh HISTORY
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A
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.Fn time
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function appeared in
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.At v2 .
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It returned a 32-bit value measuring sixtieths of a second, leading to
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rollover every 2.26 years.
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In
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.At v6 ,
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the precision of
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.Fn time
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was changed to seconds, allowing 135.6 years between rollovers.
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.Pp
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In
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.Nx 6.0
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the
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.Vt time_t
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type was changed to be 64 bits wide, including on 32-bit machines,
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making rollover a concern for the far distant future only.
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Note however that any code making the incorrect assumption that
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.Vt time_t
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is the same as
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.Vt long
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will fail on 32-bit machines in 2038.
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