1.\" Copyright (c) 1983, 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. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)fsync.2 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD: src/lib/libc/sys/fsync.2,v 1.6.2.8 2001/12/14 18:34:00 ru Exp $ 30.\" $DragonFly: src/lib/libc/sys/fsync.2,v 1.2 2003/06/17 04:26:47 dillon Exp $ 31.\" 32.Dd June 4, 1993 33.Dt FSYNC 2 34.Os 35.Sh NAME 36.Nm fsync 37.Nd "synchronise changes to a file" 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In unistd.h 42.Ft int 43.Fn fsync "int fd" 44.Sh DESCRIPTION 45.Fn Fsync 46causes all modified data and attributes of 47.Fa fd 48to be moved to a permanent storage device. 49This normally results in all in-core modified copies 50of buffers for the associated file to be written to a disk. 51.Pp 52.Fn Fsync 53should be used by programs that require a file to be 54in a known state, for example, in building a simple transaction 55facility. 56.Sh RETURN VALUES 57.Rv -std fsync 58.Sh ERRORS 59The 60.Fn fsync 61fails if: 62.Bl -tag -width Er 63.It Bq Er EBADF 64.Fa fd 65is not a valid descriptor. 66.It Bq Er EINVAL 67.Fa fd 68refers to a socket, not to a file. 69.It Bq Er EIO 70An I/O error occurred while reading from or writing to the file system. 71.El 72.Sh SEE ALSO 73.Xr sync 2 , 74.Xr syncer 4 , 75.Xr sync 8 76.Sh HISTORY 77The 78.Fn fsync 79function call appeared in 80.Bx 4.2 . 81