attr(1)                                                                attr(1)



NAME
     attr - manipulate Extended Attributes on filesystem objects

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

     attr [ -LRq ] -g attrname pathname

     attr [ -LRq ] -r attrname pathname

     attr [ -LRq ] -l pathname


OVERVIEW
     Extended Attributes implement the ability for a user to attach name/value
     pairs to objects within the filesystem.  They are currently only
     supported in XFS filesystems.

     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
     provide a reduced resolution overview of a high resolution graphic image.

     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 256KB of arbitrary binary data.

     Attributes can be attached to all types of inodes:  regular files,
     directories, symbolic links, device nodes, etc.

     There are 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.

     Attributes are currently supported only in the XFS filesystem type.

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



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attr(1)                                                                attr(1)



          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 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 messages (to stderr) but will not print status messages (to
     stdout).

NOTES
     The standard file interchange/archive programs tar(1), cpio(1), and
     bru(1) will not archive or restore Extended Attributes, while the
     xfsdump(1m) program will.

SEE ALSO
     attr_get(2), attr_getf(2), attr_list(2), attr_listf(2), attr_multi(2),
     attr_multif(2), attr_remove(2), attr_removef(2), attr_set(2),
     attr_setf(2), xfsdump(1m).








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