1.\" Copyright (c) 1980, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 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.\" @(#)sync.8 8.1 (Berkeley) 5/31/93 33.\" $Id$ 34.\" 35.Dd May 31, 1993 36.Dt SYNC 8 37.Os BSD 4 38.Sh NAME 39.Nm sync 40.Nd force completion of pending disk writes (flush cache) 41.Sh SYNOPSIS 42.Nm sync 43.Sh DESCRIPTION 44.Nm Sync 45can be called to insure that all disk writes have been completed before the 46processor is halted in a way not suitably done by 47.Xr reboot 8 48or 49.Xr halt 8 . 50Generally, it is preferable to use 51.Xr reboot 52or 53.Xr halt 54to shut down the system, 55as they may perform additional actions 56such as resynchronizing the hardware clock 57and flushing internal caches before performing a final 58.Nm sync . 59.Pp 60.Nm Sync 61utilizes the 62.Xr sync 2 63function call. 64.Sh SEE ALSO 65.Xr sync 2 , 66.Xr fsync 2 , 67.Xr halt 8 , 68.Xr reboot 8 , 69.Xr update 8 70.Sh HISTORY 71A 72.Nm sync 73command appeared in 74.At v6 . 75