1.\" Copyright (c) 1983 The Regents of the University of California. 2.\" 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.\" from: @(#)fsync.2 6.7 (Berkeley) 3/10/91 33.\" $Id: fsync.2,v 1.3 1993/11/25 00:38:43 jtc Exp $ 34.\" 35.Dd March 10, 1991 36.Dt FSYNC 2 37.Os BSD 4.2 38.Sh NAME 39.Nm fsync 40.Nd "synchronize a file's in-core state with that on disk" 41.Sh SYNOPSIS 42.Fd #include <unistd.h> 43.Ft int 44.Fn fsync "int fd" 45.Sh DESCRIPTION 46.Fn Fsync 47causes all modified data and attributes of 48.Fa fd 49to be moved to a permanent storage device. 50This normally results in all in-core modified copies 51of buffers for the associated file to be written to a disk. 52.Pp 53.Fn Fsync 54should be used by programs that require a file to be 55in a known state, for example, in building a simple transaction 56facility. 57.Sh RETURN VALUES 58A 0 value is returned on success. A -1 value indicates 59an error. 60.Sh ERRORS 61The 62.Fn fsync 63fails if: 64.Bl -tag -width Er 65.It Bq Er EBADF 66.Fa Fd 67is not a valid descriptor. 68.It Bq Er EINVAL 69.Fa Fd 70refers to a socket, not to a file. 71.It Bq Er EIO 72An I/O error occurred while reading from or writing to the file system. 73.El 74.Sh SEE ALSO 75.Xr sync 2 , 76.Xr sync 8 , 77.Xr update 8 78.Sh HISTORY 79The 80.Fn fsync 81function call appeared in 82.Bx 4.2 . 83