gen/FreeBSD/time.3

   1 .\" Copyright (c) 1989, 1991, 1993
   2 .\"     The Regents of the University of California.  All rights reserved.
   3 .\"
   4 .\" This code is derived from software contributed to Berkeley by
   5 .\" the American National Standards Committee X3, on Information
   6 .\" Processing Systems.
   7 .\"
   8 .\" Redistribution and use in source and binary forms, with or without
   9 .\" modification, are permitted provided that the following conditions
  10 .\" are met:
  11 .\" 1. Redistributions of source code must retain the above copyright
  12 .\"    notice, this list of conditions and the following disclaimer.
  13 .\" 2. Redistributions in binary form must reproduce the above copyright
  14 .\"    notice, this list of conditions and the following disclaimer in the
  15 .\"    documentation and/or other materials provided with the distribution.
  16 .\" 4. Neither the name of the University nor the names of its contributors
  17 .\"    may be used to endorse or promote products derived from this software
  18 .\"    without specific prior written permission.
  19 .\"
  20 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30 .\" SUCH DAMAGE.
  31 .\"
  32 .\"     @(#)time.3      8.1 (Berkeley) 6/4/93
  33 .\" $FreeBSD: src/lib/libc/gen/time.3,v 1.15 2007/01/09 00:27:55 imp Exp $
  34 .\"
  35 .Dd July 18, 2003
  36 .Dt TIME 3
  37 .Os
  38 .Sh NAME
  39 .Nm time
  40 .Nd get time of day
  41 .Sh LIBRARY
  42 .Lb libc
  43 .Sh SYNOPSIS
  44 .In time.h
  45 .Ft time_t
  46 .Fn time "time_t *tloc"
  47 .Sh DESCRIPTION
  48 The
  49 .Fn time
  50 function
  51 returns the value of time in seconds since 0 hours, 0 minutes,
  52 0 seconds, January 1, 1970, Coordinated Universal Time,
  53 without including leap seconds.
  54 If an error occurs,
  55 .Fn time
  56 returns the value
  57 .Po Vt time_t Pc Ns \-1 .
  58 .Pp
  59 The return value is also stored in
  60 .No \&* Ns Va tloc ,
  61 provided that
  62 .Va tloc
  63 is non-null.
  64 .Sh ERRORS
  65 The
  66 .Fn time
  67 function may fail for any of the reasons described in
  68 .Xr gettimeofday 2 .
  69 .Sh SEE ALSO
  70 .Xr gettimeofday 2 ,
  71 .Xr ctime 3
  72 .Sh STANDARDS
  73 The
  74 .Nm
  75 function conforms to
  76 .St -p1003.1-2001 .
  77 .Sh HISTORY
  78 A
  79 .Fn time
  80 function appeared in
  81 .At v6 .
  82 .Sh BUGS
  83 Neither
  84 .St -isoC-99
  85 nor
  86 .St -p1003.1-2001
  87 requires
  88 .Fn time
  89 to set
  90 .Va errno
  91 on failure; thus, it is impossible for an application to distinguish
  92 the valid time value \-1 (representing the last UTC second of 1969)
  93 from the error return value.
  94 .Pp
  95 Systems conforming to earlier versions of the C and
  96 .Tn POSIX
  97 standards (including older versions of
  98 .Fx )
  99 did not set
 100 .No \&* Ns Va tloc
 101 in the error case.