.\" Copyright (c) 1983 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)fsync.2	6.4 (Berkeley) 5/22/86
.\"
.TH FSYNC 2 "May 22, 1986"
.UC 5
.SH NAME
fsync \- synchronize a file's in-core state with that on disk
.SH SYNOPSIS
.ft B
fsync(fd)
.br
int fd;
.ft R
.SH DESCRIPTION
.I Fsync
causes all modified data and attributes of \fIfd\fP
to be moved to a permanent storage device.
This normally results in all in-core modified copies
of buffers for the associated file to be written to a disk.
.PP
.I Fsync
should be used by programs that require a file to be
in a known state, for example, in building a simple transaction
facility.
.SH "RETURN VALUE
A 0 value is returned on success.  A \-1 value indicates
an error.
.SH "ERRORS
The \fIfsync\fP fails if:
.TP 15
[EBADF]
\fIFd\fP is not a valid descriptor.
.TP 15
[EINVAL]
\fIFd\fP refers to a socket, not to a file.
.TP 15
[EIO]
An I/O error occurred while reading from or writing to the file system.
.SH "SEE ALSO"
sync(2), sync(8), update(8)