\"      $NetBSD: extattrctl.8,v 1.6 2025/03/10 22:19:53 christos Exp $
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\" Copyright (c) 2000-2001 Robert N. M. Watson
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\" This software was developed by Robert Watson for the TrustedBSD Project.
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\" $FreeBSD: src/usr.sbin/extattrctl/extattrctl.8,v 1.24 2005/02/09 18:04:40 ru Exp $
\"
\" Developed by the TrustedBSD Project.
\" Support for file system extended attribute.
\"
Dd March 10, 2025
Dt EXTATTRCTL 8
Os
Sh NAME
Nm extattrctl
Nd manage UFS1 extended attributes
Sh SYNOPSIS
Nm
Cm start
Ar path
Nm
Cm stop
Ar path
Nm
Cm initattr
Op Fl f
Op Fl p Ar path
Ar attrsize
Ar attrfile
Nm
Cm showattr
Ar attrfile
Nm
Cm enable
Ar path
Ar attrnamespace
Ar attrname
Ar attrfile
Nm
Cm disable
Ar path
Ar attrnamespace
Ar attrname
Sh DESCRIPTION
The
Nm
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.
Pp
The first argument on the command line indicates the operation to be
performed.
Operation must be one of the following:
Bl -tag -width indent
It Cm start Ar path
Start extended attribute support on the file system named using
Ar path .
The file system must be a UFS1 file system, and the
Dv UFS_EXTATTR
kernel option must have been enabled.
If
Pa .attribute/user
and
Pa .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
Cm -o extattr
option to
Xr mount 8 .
It Cm stop Ar path
Stop extended attribute support on the file system named using
Ar path .
Extended attribute support must previously have been started.
It Cm initattr Oo Fl f Oc Oo Fl p Ar path Oc Ar 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
Ar attrsize ,
as well as the file where the attribute will be stored, using
Ar attrfile .
Pp
The
Fl 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.
Pp
The
Fl p Ar 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 available
for attributes when they are written, preventing low disk space conditions
from denying attribute service.
Pp
This file should not exist before running
Cm initattr .
Pp
When a user attempts to set a
Dq user
or
Dq system
extended attribute that lacks a backing file,
the kernel will attempt to automatically create it, provided
Pa .attribute/user
or
Pa .attribute/system
exist and are writable by the requesting user.
It Cm showattr Ar attrfile
Show the attribute header values in the attribute file named by
Ar attrfile .
It Cm enable Ar path attrnamespace attrname attrfile
Enable an attribute named
Ar attrname
in the namespace
Ar attrnamespace
on the file system identified using
Ar path ,
and backed by initialized attribute file
Ar attrfile .
Available namespaces are
Dq user
and
Dq system .
The backing file must have been initialized using
Cm initattr
before its first use.
Attributes must have been started on the file system prior to the
enabling of any attributes.
It Cm disable Ar path attrnamespace attrname
Disable the attributed named
Ar attrname
in namespace
Ar attrnamespace
on the file system identified by
Ar path .
Available namespaces are
Dq user
and
Dq system .
The file system must have attributes started on it, and the attribute
most have been enabled using
Cm enable .
El
Sh EXAMPLES
Dl extattrctl start /
Pp
Start extended attributes on the root file system.
Pp
Dl extattrctl initattr 17 /.attribute/system/md5
Pp
Create an attribute backing file in
Pa /.attribute/system/md5 ,
and set the maximum size of each attribute to 17 bytes, with a
sparse file used for storing the attributes.
Pp
Dl extattrctl enable / system md5 /.attribute/system/md5
Pp
Enable an attribute named md5 on the root file system, backed from the file
Pa /.attribute/system/md5 .
Pp
Dl extattrctl disable / system md5
Pp
Disable the attribute named md5 on the root file system.
Pp
Dl extattrctl stop /
Pp
Stop extended attributes on the root file system.
Sh SEE ALSO
Xr getextattr 1 ,
Xr extattr_get_file 2 ,
Xr extattrctl 2 ,
\" .Xr ffs 7 ,
Xr extattr 9
Sh HISTORY
Extended attribute support was developed as part of the TrustedBSD
Project, and introduced in
Fx 5.0
and
Nx 4.0 .
It was developed to support security extensions requiring additional
labels to be associated with each file or directory.
Backing file autocreation was added in
Nx 6.0 .
Sh AUTHORS
An Robert N M Watson
Sh BUGS
Nm
works only on UFS1 file systems.
The kernel support for extended attribute backing files and this
control program should be generalized for any file system that
lacks native extended attribute support.

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