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ATTR(1) XFS Compatibility API ATTR(1)
NAME
attr - extended attributes on XFS filesystem objects
SYNOPSIS
attr [ -LRq ] -s attrname [ -V attrvalue ] pathname
attr [ -LRq ] -g attrname pathname
attr [ -LRq ] -r attrname pathname
OVERVIEW
Extended attributes implement the ability for a user to attach name:value pairs to
objects within the XFS filesystem.
They could be used to store meta-information about the file. For example "charac-
ter-set=kanji" could tell a document browser to use the Kanji character set when
displaying that document and "thumbnail=..." could provide a reduced resolution
overview of a high resolution graphic image.
This document describes the attr command, which is mostly compatible with the IRIX
command of the same name. It is thus aimed specifically at users of the XFS
filesystem - for filesystem independent extended attribute manipulation, consult
the getfattr(1) and setfattr(1) documentation.
In the XFS filesystem, the names can be up to 256 bytes in length, terminated by
the first 0 byte. The intent is that they be printable ASCII (or other character
set) names for the attribute. The values can be up to 64KB of arbitrary binary
data.
Attributes can be attached to all types of XFS inodes: regular files, directories,
symbolic links, device nodes, etc.
XFS uses 2 disjoint attribute name spaces associated with every filesystem object.
They are the root and user address spaces. The root address space is accessable
only to the superuser, and then only by specifying a flag argument to the function
call. Other users will not see or be able to modify attributes in the root address
space. The user address space is protected by the normal file permissions mecha-
nism, so the owner of the file can decide who is able to see and/or modify the
value of attributes on any particular file.
DESCRIPTION
The attr utility allows the manipulation of extended attributes associated with
filesystem objects from within shell scripts.
There are four main operations that attr can perform:
GET The -g attrname option tells attr to search the named object and print (to
stdout) the value associated with that attribute name. With the -q flag,
stdout will be exactly and only the value of the attribute, suitable for
storage directly into a file or processing via a piped command.
REMOVE The -r attrname option tells attr to remove an attribute with the given name
from the object if the attribute exists. There is no output on sucessful
completion.
SET/CREATE
The -s attrname option tells attr to set the named attribute of the object
to the value read from stdin. If an attribute with that name already
exists, its value will be replaced with this one. If an attribute with that
name does not already exist, one will be created with this value. With the
-V attrvalue flag, the attribute will be set to have a value of attrvalue
and stdin will not be read. With the -q flag, stdout will not be used.
Without the -q flag, a message showing the attribute name and the entire
value will be printed.
When the -L option is given and the named object is a symbolic link, operate on the
attributes of the object referenced by the symbolic link. Without this option,
operate on the attributes of the symbolic link itself.
When the -R option is given and the process has appropriate privileges, operate in
the root attribute namespace rather that the USER attribute namespace.
When the -q option is given attr will try to keep quiet. It will output error mes-
sages (to stderr) but will not print status messages (to stdout).
NOTES
The standard file interchange/archive programs tar(1), and cpio(1) will not archive
or restore extended attributes, while the xfsdump(8) program will.
CAVEATS
The list option present in the IRIX version of this command is not supported. get-
fattr provides a mechanism to retrieve all of the attribute names.
SEE ALSO
getfattr(1), setfattr(1), attr_get(3), attr_set(3), attr_multi(3), attr_remove(3),
attr(5), and xfsdump(8).
Dec 2001 Extended Attributes ATTR(1)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache/1.3.41 (Unix) PHP/5.2.5 mod_perl/1.30 mod_gzip/1.3.26.1a
Under GNU General Public License
2009-01-08 05:31 @38.103.63.58 CrawledBy CCBot/1.0 (+http://www.commoncrawl.org/bot.html)