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

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.\" Copyright (c) 1989, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
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.\" This code is derived from software contributed to Berkeley by
.\" the American National Standards Committee X3, on Information
.\" Processing Systems.
.\"
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.\" This product includes software developed by the University of
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.\" may be used to endorse or promote products derived from this software
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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.