1.\"- 2.\" Copyright (c) 1999 Robert N. M. Watson 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD: src/share/man/man9/extattr.9,v 1.1.2.4 2001/12/17 11:30:18 ru Exp $ 27.\" 28.Dd May 8, 2010 29.Dt EXTATTR 9 30.Os 31.Sh NAME 32.Nm extattr 33.Nd virtual file system named extended attributes 34.Sh SYNOPSIS 35.In sys/param.h 36.In sys/vnode.h 37.In sys/extattr.h 38.Sh DESCRIPTION 39Named extended attributes allow additional meta-data to be associated 40with vnodes representing files and directories. 41The semantics of this additional data is that of a "name=value" pair, where 42a name may be defined or undefined, and if defined, associated with zero or 43more bytes of arbitrary binary data. 44.Pp 45Reads of extended attribute data may return specific contiguous regions of 46the meta-data, in the style of 47.Xr VOP_READ 9 , 48but writes will replace the entire current "value" associated with 49a given name. 50As there are a plethora of file systems with differing extended attributes, 51availability and functionality of these functions may be limited, and they 52should be used with awareness of the underlying semantics of the supporting 53file system. 54Authorization schemes for extended attribute data may also vary by file 55system, as well as maximum attribute size, and whether or not any or 56specific new attributes may be defined. 57.Pp 58Extended attributes are named using a null-terminated character string. 59Depending on underlying file system semantics, this name may or may not be 60case-sensitive. 61Appropriate vnode extended attribute calls are: 62.Xr VOP_GETEXTATTR 9 63and 64.Xr VOP_SETEXTATTR 9 . 65.Sh SEE ALSO 66.Xr VFS 9 , 67.Xr VOP_GETEXTATTR 9 , 68.Xr VOP_SETEXTATTR 9 69.Sh AUTHORS 70This manual page was written by 71.An Robert Watson . 72