fsync.2

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)fsync.2	8.2	9/12/90
.TH fsync 2
.SH Name
fsync \- synchronize a file's in-core state with that on disk
.SH Syntax
fsync(\fIfd\fP)
.br
int \fIfd\fP;
.SH Description
.NXR "fsync system call"
.NXR "file" "synchronizing buffers with disk"
The
.PN fsync
system call causes all modified data and attributes of 
.I fd
to be moved to a permanent storage device.
This results in all in-core modified copies
of buffers for the associated file to be written to a disk.
.PP
The
.PN fsync
call 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 Values
A 0 value is returned on success.  A \-1 value indicates
an error.
.SH Diagnostics
The 
.PN fsync
call fails under the following conditions:
.TP 15
[EBADF]
The 
.I fd
argument is not a valid descriptor.
.TP
[EINVAL]
The
.I fd
argument refers to a socket.
.TP
[EIO]
An I/O error occurred while reading from or writing to the file
system. 
.TP
[EINTR]
The
.PN fsync()
function was interrupted by a signal.
.PP
If an error occurs on an
asynchronous write over NFS, the error cannot always 
be returned from a
.PN write
system call.  The error code is returned on
.PN close
or
.PN fsync .
The following are NFS-only error messages:
.TP 15
[EACCESS]
The requested address is protected, and the current user
has inadequate permission to access it. 
.TP 15
[ENOSPC]
There is no free space remaining on the file system containing
the file.
.TP 15
[EDQUOT]
The user's quota of disk blocks on the file system containing
the file has been exhausted.
.TP 15
[EROFS]
The file is on a read-only file system.
.TP 15
[ESTALE]
The
.I fd
argument is invalid because the file referred
to by that file handle no longer exists or has been revoked. 
.TP
[ETIMEDOUT]
A write operation failed
because the server
did not properly respond after a period
of time that is dependent on the
.MS mount 8nfs
options.
.SH See Also
sync(1), close(2), sync(2), write(2), update(8)