projects / apple / system_cmds.git / blame
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| 1815bff5 A |
1 | .\" Copyright (c) 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 | .\" @(#)update.8 8.3 (Berkeley) 4/19/94 | |
| 33 | .\" | |
| 34 | .Dd April 19, 1994 | |
| 35 | .Dt UPDATE 8 | |
| 36 | .Os | |
| 37 | .Sh NAME | |
| 38 | .Nm update | |
| 39 | .Nd flush internal filesystem caches to disk frequently | |
| 40 | .Sh SYNOPSIS | |
| 41 | .Nm update | |
| 83f6dbe8 | 42 | .Op Ar normal_interval Op Ar save_energy_interval |
| 1815bff5 A |
43 | .Sh DESCRIPTION |
| 44 | The | |
| 45 | .Nm update | |
| 46 | command helps protect the integrity of disk volumes | |
| 47 | by flushing | |
| 48 | volatile cached filesystem data | |
| 49 | to disk at thirty second intervals. | |
| 50 | .Nm Update | |
| 51 | uses the | |
| 52 | .Xr sync 2 | |
| 53 | function call to do the task. | |
| 83f6dbe8 A |
54 | The normal_interval and save_energy_interval can be used to set the |
| 55 | .Xr sync 2 interval in seconds of the normal case and the case where the computer is trying to save energy. | |
| 1815bff5 A |
56 | .Pp |
| 57 | .Nm Update | |
| 58 | is commonly invoked at startup time by | |
| 59 | .Xr rc 8 | |
| 60 | when the system goes multi-user. | |
| 61 | .Sh SEE ALSO | |
| 62 | .Xr sync 2 , | |
| 63 | .Xr fsck 8 , | |
| 64 | .Xr init 8 , | |
| 65 | .Xr rc 8 , | |
| 66 | .Xr sync 8 | |
| 67 | .Sh BUGS | |
| 68 | It is possible on some systems that a | |
| 69 | .Xr sync | |
| 70 | occurring simultaneously with a crash may cause | |
| 71 | file system damage. See | |
| 72 | .Xr fsck 8 . | |
| 73 | .Sh HISTORY | |
| 74 | An | |
| 75 | .Nm update | |
| 76 | command appeared in | |
| 77 | .At v6 . |