1.\" $NetBSD: time.3,v 1.15 2010/04/24 01:35:50 dholland Exp $ 2.\" 3.\" Copyright (c) 1989, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" the American National Standards Committee X3, on Information 8.\" Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)time.3 8.1 (Berkeley) 6/4/93 35.\" 36.Dd April 23, 2010 37.Dt TIME 3 38.Os 39.Sh NAME 40.Nm time 41.Nd get time of day 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In time.h 46.Ft time_t 47.Fn time "time_t *tloc" 48.Sh DESCRIPTION 49The 50.Fn time 51function 52returns the value of time in seconds since 0 hours, 0 minutes, 530 seconds, January 1, 1970, Coordinated Universal Time. 54.Pp 55A copy of the time value may be saved to the area indicated by the 56pointer 57.Fa tloc . 58If 59.Fa tloc 60is a 61.Dv NULL 62pointer, no value is stored. 63.Pp 64Upon successful completion, 65.Fn time 66returns the value of time. 67Otherwise a value of 68.Po 69.Po Fa time_t Pc \-1 70.Pc 71is returned and the global variable 72.Va errno 73is set to indicate the error. 74.Sh ERRORS 75The following error codes may be set in 76.Va errno : 77.Bl -tag -width Er 78.It Bq Er EFAULT 79An argument address referenced invalid memory. 80.El 81.Sh SEE ALSO 82.Xr gettimeofday 2 , 83.Xr ctime 3 84.Sh STANDARDS 85The 86.Fn time 87function conforms to 88.St -p1003.1-90 . 89.Sh HISTORY 90A 91.Fn time 92function appeared in 93.At v2 . 94It returned a 32-bit value measuring sixtieths of a second, leading to 95rollover every 2.26 years. 96In 97.At v6 , 98the precision of 99.Fn time 100was changed to seconds, allowing 135.6 years between rollovers. 101.Pp 102In 103.Nx 6.0 104the 105.Vt time_t 106type was changed to be 64 bits wide, including on 32-bit machines, 107making rollover a concern for the far distant future only. 108Note however that any code making the incorrect assumption that 109.Vt time_t 110is the same as 111.Vt long 112will fail on 32-bit machines in 2038. 113