attr(1) — Linux manual page

NAME | SYNOPSIS | OVERVIEW | DESCRIPTION | NOTES | CAVEATS | AUTHOR | SEE ALSO | COLOPHON

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.

       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         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, <andreas.gruenbacher@gmail.com> and the SGI
       XFS development team, <linux-xfs@oss.sgi.com>.

       Please send your bug reports or comments to
       <https://savannah.nongnu.org/bugs/?group=attr > or <acl-
       devel@nongnu.org>.

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 ⟨http://savannah.nongnu.org/projects/attr⟩.  If you have a bug
       report for this manual page, see
       ⟨http://savannah.nongnu.org/bugs/?group=attr⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨git://git.savannah.nongnu.org/attr.git⟩ on 2021-06-20.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-04-19.)  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 improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

Dec 2001                   Extended Attributes                   ATTR(1)

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