attr(1) — Linux manual page


ATTR(1)                     XFS Compatibility API                    ATTR(1)

NAME         top

       attr - extended attributes on XFS filesystem objects

SYNOPSIS         top

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

       attr [ -LRSq ] -g attrname pathname

       attr [ -LRSq ] -r attrname pathname

       attr [ -LRSq ] -l pathname

OVERVIEW         top

       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         top

       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.

              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

       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         top

       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         top

       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         top

       Andreas Gruenbacher, <> and the SGI XFS
       development team, <>.

       Please send your bug reports or comments to
       < > or <acl->.

SEE ALSO         top

       getfattr(1), setfattr(1), attr_get(3), attr_set(3), attr_multi(3),
       attr_remove(3), attr(5), xfsdump(8)

COLOPHON         top

       This page is part of the attr (manipulating filesystem extended
       attributes) project.  Information about the project can be found at
       ⟨⟩.  If you have a bug report
       for this manual page, see
       ⟨⟩.  This page was ob‐
       tained from the project's upstream Git repository
       ⟨git://⟩ on 2020-11-01.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-10-08.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or im‐
       provements to the information in this COLOPHON (which is not part of
       the original manual page), send a mail to

Dec 2001                     Extended Attributes                     ATTR(1)

Pages that refer to this page: attr_get(3)attr_getf(3)attr_list(3)attr_listf(3)attr_multi(3)attr_multif(3)attr_remove(3)attr_removef(3)attr_set(3)attr_setf(3)xattr(7)mount(8)xfsdump(8)