projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 931b8415 CL |
1 | .\" Copyright (c) 1980, 1991 Regents of the University of California. |
| 2 | .\" All rights reserved. | |
| 5f440b1e | 3 | .\" |
| 931b8415 | 4 | .\" %sccs.include.redist.man% |
| 5f440b1e | 5 | .\" |
| 931b8415 CL |
6 | .\" @(#)sync.2 6.3 (Berkeley) %G% |
| 7 | .\" | |
| 8 | .Dd | |
| 9 | .Dt SYNC 2 | |
| 10 | .Os BSD 4 | |
| 11 | .Sh NAME | |
| 12 | .Nm sync | |
| 13 | .Nd "synchronize disk block in-core status with that on disk" | |
| 14 | .Sh SYNOPSIS | |
| 15 | .Fd #include <unistd.h> | |
| 16 | .Ft void | |
| 17 | .Fn sync void | |
| 18 | .Sh DESCRIPTION | |
| 19 | The | |
| 20 | .Fn sync | |
| 21 | function forces a write of dirty (modified) buffers | |
| 22 | in the block buffer cache out | |
| 23 | to disk. The kernel keeps this information in core to reduce | |
| 24 | the number of disk I/O transfers required by the system. | |
| 25 | As information in the cache is lost after a system crash a | |
| 26 | .Fn sync | |
| 27 | call is issued | |
| 28 | frequently | |
| 29 | by the user process | |
| 30 | .Xr update 8 | |
| 31 | (about every 30 seconds). | |
| 32 | .Pp | |
| 33 | The function | |
| 34 | .Xr fsync 2 | |
| 35 | may be used to synchronize individual file descriptor | |
| 36 | attributes. | |
| 37 | .Sh SEE ALSO | |
| 38 | .Xr fsync 2 , | |
| 39 | .Xr sync 8 , | |
| 40 | .Xr update 8 | |
| 41 | .Sh BUGS | |
| 42 | .Fn Sync | |
| 43 | may return before the buffers are completely flushed. | |
| 44 | .Sh HISTORY | |
| 45 | A | |
| 46 | .Nm | |
| 47 | function call appeared in Version 6 AT&T UNIX. |