1.\" $NetBSD: time.9,v 1.1 1995/11/25 21:24:53 perry Exp $ 2.\" 3.\" Copyright (c) 1994 Christopher G. Demetriou 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by Christopher G. Demetriou 17.\" for the NetBSD Project. 18.\" 3. The name of the author may not be used to endorse or promote products 19.\" derived from this software without specific prior written permission 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31.\" 32.\" $FreeBSD: src/share/man/man9/time.9,v 1.3.2.5 2001/08/17 13:08:54 ru Exp $ 33.\" $DragonFly: src/share/man/man9/time.9,v 1.3 2008/04/09 21:41:59 swildner Exp $ 34.\" 35.Dd April 9, 2008 36.Dt TIME 9 37.Os 38.Sh NAME 39.Nm boottime , 40.Nm time_second 41.Nd system time variables 42.Sh SYNOPSIS 43.In sys/time.h 44.Pp 45.Vt extern struct timeval boottime ; 46.Vt extern time_t time_second ; 47.Sh DESCRIPTION 48The 49.Va boottime 50variable holds the system boot time. 51The 52.Va time_second 53variable is the system's 54.Dq wall time 55clock to the second. 56.Pp 57The 58.Xr microtime 9 , 59.Xr getmicrotime 9 , 60.Xr nanotime 9 , 61and 62.Xr getnanotime 9 63functions can be used to get the current time in an atomic manner. 64Similarly, the 65.Xr microuptime 9 , 66.Xr getmicrouptime 9 , 67.Xr nanouptime 9 , 68and 69.Xr getnanouptime 9 70functions can be used to get the time elapsed since boot in an atomic manner. 71The 72.Va boottime 73variable may be read and written without special precautions. 74.Sh SEE ALSO 75.Xr clock_settime 2 , 76.Xr ntp_adjtime 2 , 77.Xr settimeofday 2 , 78.Xr inittodr 9 , 79.Xr microtime 9 , 80.Xr microuptime 9 81