freebsd-skq/lib/libc/gen/time.3

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.\" Copyright (c) 1989, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" the American National Standards Committee X3, on Information
.\" Processing Systems.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
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.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 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.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" @(#)time.3 8.1 (Berkeley) 6/4/93
1999-08-28 00:22:10 +00:00
.\" $FreeBSD$
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.\"
.Dd July 18, 2003
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.Dt TIME 3
.Os
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.Sh NAME
.Nm time
.Nd get time of day
.Sh LIBRARY
.Lb libc
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.Sh SYNOPSIS
.In time.h
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.Ft time_t
.Fn time "time_t *tloc"
.Sh DESCRIPTION
The
.Fn time
function
returns the value of time in seconds since 0 hours, 0 minutes,
0 seconds, January 1, 1970, Coordinated Universal Time.
If an error occurs,
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.Fn time
returns the value
.Po Vt time_t Pc Ns \-1 .
.Pp
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The return value is also stored in
.No \&* Ns Va tloc ,
provided that
.Va tloc
is non-null.
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.Sh ERRORS
The
.Fn time
function may fail for any of the reasons described in
.Xr gettimeofday 2 .
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.Sh SEE ALSO
.Xr gettimeofday 2 ,
.Xr ctime 3
.Sh STANDARDS
The
.Nm
function conforms to
.St -p1003.1-2001 .
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.Sh HISTORY
A
.Fn time
function appeared in
.At v6 .
.Sh BUGS
Neither
.St -isoC-99
nor
.St -p1003.1-2001
requires
.Fn time
to set
.Va errno
on failure; thus, it is impossible for an application to distinguish
the valid time value \-1 (representing the last UTC second of 1969)
from the error return value.
.Pp
Systems conforming to earlier versions of the C and
.Tn POSIX
standards (including older versions of
.Fx )
did not set
.No \&* Ns Va tloc
in the error case.