system_cmds-433.8.tar.gz

[apple/system_cmds.git] / update.tproj / update.8

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.\"	@(#)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
.Op Ar normal_interval Op Ar save_energy_interval
.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.
The normal_interval and save_energy_interval can be used to set the
.Xr sync 2 interval in seconds of the normal case and the case where the computer is trying to save energy.
.Pp
.Nm Update
is invoked at startup time by
.Xr launchd 8
when the system goes multi-user.
.Sh SEE ALSO
.Xr sync 2 ,
.Xr fsck 8 ,
.Xr launchd 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 .