1.\" $NetBSD: sync.8,v 1.12 2001/12/20 20:03:30 wiz Exp $ 2.\" 3.\" Copyright (c) 1980, 1991, 1993 4.\" The Regents of the University of California. 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 the University of 17.\" California, Berkeley and its contributors. 18.\" 4. 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.\" @(#)sync.8 8.1 (Berkeley) 5/31/93 35.\" 36.Dd May 31, 1993 37.Dt SYNC 8 38.Os 39.Sh NAME 40.Nm sync 41.Nd force completion of pending disk writes (flush cache) 42.Sh SYNOPSIS 43.Nm sync 44.Sh DESCRIPTION 45The 46.Nm 47program can be called to ensure that all disk writes have been 48completed before the processor is halted in a way not suitably done by 49.Xr reboot 8 50or 51.Xr halt 8 . 52Generally, it is preferable to use 53.Xr reboot 8 54or 55.Xr halt 8 56to shut down the system, 57as they may perform additional actions 58such as resynchronizing the hardware clock 59and flushing internal caches before performing a final 60.Nm "" . 61.Pp 62The 63.Nm 64program simply invokes the 65.Xr sync 2 66system call. 67.Sh SEE ALSO 68.Xr fsync 2 , 69.Xr sync 2 , 70.Xr halt 8 , 71.Xr reboot 8 72.Sh HISTORY 73A 74.Nm 75command appeared in 76.At v6 . 77