107 lines
3.2 KiB
Groff
107 lines
3.2 KiB
Groff
.\" Copyright (c) 1983, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)fsync.2 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd June 4, 1993
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.Dt FSYNC 2
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.Os BSD 4.2
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.Sh NAME
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.Nm fsync
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.Nd "synchronise changes to a file"
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.Fd #include <unistd.h>
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.Ft int
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.Fn fsync "int fd"
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.Sh DESCRIPTION
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.Fn Fsync
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causes all modified data and attributes of
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.Fa fd
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to be moved to a permanent storage device.
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This normally results in all in-core modified copies
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of buffers for the associated file to be written to a disk.
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.Pp
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.Fn Fsync
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should be used by programs that require a file to be
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in a known state, for example, in building a simple transaction
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facility.
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.Sh IMPLEMENTATION NOTES
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.Pp
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In the non-threaded library
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.Fn fsync
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is implemented as the
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.Va fsync
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syscall.
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.Pp
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In the threaded library, the
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.Va fsync
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syscall is assembled to
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.Fn _thread_sys_fsync
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and
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.Fn fsync
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is implemented as a function which locks
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.Fa fd
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for read and write, then calls
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.Fn _thread_sys_fsync .
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Before returning,
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.Fn fsync
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unlocks
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.Fa fd .
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.Sh RETURN VALUES
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A 0 value is returned on success. A -1 value indicates
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an error.
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.Sh ERRORS
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The
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.Fn fsync
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fails if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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.Fa Fd
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is not a valid descriptor.
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.It Bq Er EINVAL
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.Fa Fd
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refers to a socket, not to a file.
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to the file system.
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.El
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.Sh SEE ALSO
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.Xr sync 2 ,
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.Xr syncer 4 ,
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.Xr sync 8
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.Sh HISTORY
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The
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.Fn fsync
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function call appeared in
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.Bx 4.2 .
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