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 "character-set=kanji"  could  tell  a
       document  browser  to  use  the Kanji character set when
       displaying that document and "thumbnail=..." could  pro-
       vide  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 set-
       fattr(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 access-
       able 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.

       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  appro-
       priate  privileges, operate in the root attribute names-
       pace rather that the USER 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 com-
       mand 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)
