ATTR(1)			     XFS Compatibility API		       ATTR(1)

NAME
       attr - extended attributes on XFS filesystem objects

SYNOPSIS
       attr [ -LRSq ] -s attrname [ -V attrvalue ] pathname

       attr [ -LRSq ] -g attrname pathname

       attr [ -LRSq ] -r attrname pathname

       attr [ -LRSq ] -l pathname


OVERVIEW
       Extended attributes implement the ability for a user to attach
       name:value pairs to objects within the XFS filesystem.

       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.

       Extended attributes can be used to store meta-information about the
       file.  For example "character-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.

       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 accessible 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
       mechanism, 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.

       LIST   The -l option tells attr to list the names of all the attributes
	      that are associated with the object, and the number of bytes in
	      the value of each of those attributes.  With the -q flag, stdout
	      will be a simple list of only the attribute names, one per line,
	      suitable for input into a script.

       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 successful 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.

       The -S option is similar, except it specifies use of the security
       attribute namespace.

       When the -q option is given attr will try to keep quiet.	 It will
       output error messages (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.  getfattr provides a mechanism to retrieve all of the
       attribute names.

AUTHOR
       Andreas Gruenbacher, <andreas.gruenbacher@gmail.com> and the SGI XFS
       development team, <linux-xfs@oss.sgi.com>.

       Please send your bug reports or comments to
       <https://savannah.nongnu.org/bugs/?group=attr> or
       <acl-devel@nongnu.org>.

SEE ALSO
       getfattr(1), setfattr(1), attr_get(3), attr_set(3), attr_multi(3),
       attr_remove(3), xattr(7), xfsdump(8)

Dec 2001		      Extended Attributes		       ATTR(1)