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.

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)