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 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 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 stor-
              age 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 num-
              ber 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 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.

       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.

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)