1.\" $NetBSD: fsync.2,v 1.9 2002/02/08 01:28:17 ross Exp $ 2.\" 3.\" Copyright (c) 1983, 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.\" @(#)fsync.2 8.1 (Berkeley) 6/4/93 35.\" 36.Dd June 4, 1993 37.Dt FSYNC 2 38.Os 39.Sh NAME 40.Nm fsync 41.Nd "synchronize a file's in-core state with that on disk" 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.Fd #include \*[Lt]unistd.h\*[Gt] 46.Ft int 47.Fn fsync "int fd" 48.Sh DESCRIPTION 49.Fn fsync 50causes all modified data and attributes of 51.Fa fd 52to be moved to a permanent storage device. 53This normally results in all in-core modified copies 54of buffers for the associated file to be written to a disk. 55.Pp 56.Fn fsync 57should be used by programs that require a file to be 58in a known state, for example, in building a simple transaction 59facility. 60.Sh RETURN VALUES 61A 0 value is returned on success. A -1 value indicates 62an error. 63.Sh ERRORS 64The 65.Fn fsync 66fails if: 67.Bl -tag -width Er 68.It Bq Er EBADF 69.Fa fd 70is not a valid descriptor. 71.It Bq Er EINVAL 72.Fa fd 73refers to a socket, not to a file. 74.It Bq Er EIO 75An I/O error occurred while reading from or writing to the file system. 76.El 77.Sh SEE ALSO 78.Xr sync 2 , 79.Xr sync 8 80.Sh HISTORY 81The 82.Fn fsync 83function call appeared in 84.Bx 4.2 . 85