extattrctl(8) - NetBSD Manual Pages

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EXTATTRCTL(8)           NetBSD System Manager's Manual           EXTATTRCTL(8)


NAME

     extattrctl -- manage UFS1 extended attributes


SYNOPSIS

     extattrctl start path
     extattrctl stop path
     extattrctl initattr [-f] [-p path] attrsize attrfile
     extattrctl showattr attrfile
     extattrctl enable path attrnamespace attrname attrfile
     extattrctl disable path attrnamespace attrname


DESCRIPTION

     The extattrctl utility is the management utility for extended attributes
     over the UFS1 file system.  It allows the starting and stopping of
     extended attributes on a file system, as well as initialization of
     attribute backing files, and enabling and disabling of specific extended
     attributes on a file system.

     The first argument on the command line indicates the operation to be per-
     formed.  Operation must be one of the following:

     start path
             Start extended attribute support on the file system named using
             path.  The file system must be a UFS1 file system, and the
             UFS_EXTATTR kernel option must have been enabled.  If
             .attribute/user and .attribute/system exist at the filesystem
             root, extended attributes backed by files in these directories
             will be automatically enabled.  Note that extended attributes can
             be automatically started at mount time by using the -o extattr
             option to mount(8).

     stop path
             Stop extended attribute support on the file system named using
             path.  Extended attribute support must previously have been
             started.

     initattr [-f] [-p path] attrsize attrfile
             Create and initialize a file to use as an attribute backing file.
             You must specify a maximum per-inode size for the attribute in
             bytes in attrsize, as well as the file where the attribute will
             be stored, using attrfile.

             The -f argument may be used to indicate that it is alright to
             overwrite an existing attribute backing file; otherwise, if the
             target file exists, an error will be returned.

             The -p path argument may be used to preallocate space for all
             attributes rather than relying on sparse files to conserve space.
             This has the advantage of guaranteeing that space will be avail-
             able for attributes when they are written, preventing low disk
             space conditions from denying attribute service.

             This file should not exist before running initattr.

             When a user attempts to set a ``user'' or ``system'' extended
             attribute that lacks a backing file, the kernel will attempt to
             automatically create it, provided .attribute/user or
             .attribute/system exist and are writable by the requesting user.

     showattr attrfile
             Show the attribute header values in the attribute file named by
             attrfile.

     enable path attrnamespace attrname attrfile
             Enable an attribute named attrname in the namespace attrnamespace
             on the file system identified using path, and backed by initial-
             ized attribute file attrfile.  Available namespaces are ``user''
             and ``system''.  The backing file must have been initialized
             using initattr before its first use.  Attributes must have been
             started on the file system prior to the enabling of any
             attributes.

     disable path attrnamespace attrname
             Disable the attributed named attrname in namespace attrnamespace
             on the file system identified by path.  Available namespaces are
             ``user'' and ``system''.  The file system must have attributes
             started on it, and the attribute most have been enabled using
             enable.


EXAMPLES

           extattrctl start /

     Start extended attributes on the root file system.

           extattrctl initattr 17 /.attribute/system/md5

     Create an attribute backing file in /.attribute/system/md5, and set the
     maximum size of each attribute to 17 bytes, with a sparse file used for
     storing the attributes.

           extattrctl enable / system md5 /.attribute/system/md5

     Enable an attribute named md5 on the root file system, backed from the
     file /.attribute/system/md5.

           extattrctl disable / md5

     Disable the attribute named md5 on the root file system.

           extattrctl stop /

     Stop extended attributes on the root file system.


SEE ALSO

     getextattr(1), extattr_get_file(2), extattr(9)


HISTORY

     Extended attribute support was developed as part of the TrustedBSD
     Project, and introduced in FreeBSD 5.0 and NetBSD 4.0.  It was developed
     to support security extensions requiring additional labels to be associ-
     ated with each file or directory.  Backing file autocreation was added in
     NetBSD 6.0.


AUTHORS

     Robert N M Watson


BUGS

     extattrctl works only on UFS1 file systems.  The kernel support for
     extended attribute backing files and this control program should be gen-
     eralized for any file system that lacks native extended attribute sup-
     port.

NetBSD 10.1                      June 17, 2011                     NetBSD 10.1