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+.\" Copyright (c) 1991, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. All advertising materials mentioning features or use of this software
+.\"    must display the following acknowledgement:
+.\"	This product includes software developed by the University of
+.\"	California, Berkeley and its contributors.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"	@(#)update.8	8.3 (Berkeley) 4/19/94
+.\"
+.Dd April 19, 1994
+.Dt UPDATE 8
+.Os
+.Sh NAME
+.Nm update
+.Nd flush internal filesystem caches to disk frequently
+.Sh SYNOPSIS
+.Nm update
+.Sh DESCRIPTION
+The
+.Nm update
+command helps protect the integrity of disk volumes
+by flushing
+volatile cached filesystem data
+to disk at thirty second intervals.
+.Nm Update
+uses the
+.Xr sync 2
+function call to do the task.
+.Pp
+.Nm Update
+is commonly invoked at startup time by
+.Xr rc 8
+when the system goes multi-user.
+.Sh SEE ALSO
+.Xr sync 2 ,
+.Xr fsck 8 ,
+.Xr init 8 ,
+.Xr rc 8 ,
+.Xr sync 8
+.Sh BUGS
+It is possible on some systems that a
+.Xr sync
+occurring simultaneously with a crash may cause
+file system damage. See
+.Xr fsck 8 .
+.Sh HISTORY
+An
+.Nm update
+command appeared in
+.At v6 .