projects / apple / xnu.git / blame
| Commit | Line | Data |
|---|---|---|
| 9bccf70c A |
1 | .\" $NetBSD: sync.2,v 1.4 1995/02/27 12:38:41 cgd 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.2 8.1 (Berkeley) 6/4/93 | |
| 35 | .\" | |
| 36 | .Dd June 4, 1993 | |
| 37 | .Dt SYNC 2 | |
| 38 | .Os BSD 4 | |
| 39 | .Sh NAME | |
| 40 | .Nm sync | |
| 41 | .Nd "synchronize disk block in-core status with that on disk" | |
| 42 | .Sh SYNOPSIS | |
| 43 | .Fd #include <unistd.h> | |
| 44 | .Ft void | |
| 2d21ac55 A |
45 | .Fo sync |
| 46 | .Fa void | |
| 47 | .Fc | |
| 9bccf70c A |
48 | .Sh DESCRIPTION |
| 49 | The | |
| 50 | .Fn sync | |
| 51 | function forces a write of dirty (modified) buffers | |
| 52 | in the block buffer cache out | |
| 53 | to disk. The kernel keeps this information in core to reduce | |
| 54 | the number of disk I/O transfers required by the system. | |
| 55 | As information in the cache is lost after a system crash a | |
| 56 | .Fn sync | |
| 57 | call is issued | |
| 58 | frequently | |
| 59 | by the user process | |
| 60 | .Xr update 8 | |
| 61 | (about every 30 seconds). | |
| 62 | .Pp | |
| 63 | The function | |
| 64 | .Xr fsync 2 | |
| 65 | may be used to synchronize individual file descriptor | |
| 66 | attributes. | |
| 67 | .Sh SEE ALSO | |
| 68 | .Xr fsync 2 , | |
| 69 | .Xr sync 8 , | |
| 70 | .Xr update 8 | |
| 71 | .Sh BUGS | |
| 39037602 | 72 | .Fn sync |
| 9bccf70c A |
73 | may return before the buffers are completely flushed. |
| 74 | .Sh HISTORY | |
| 75 | A | |
| 76 | .Fn sync | |
| 77 | function call appeared in | |
| 78 | .At v6 . |