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
performed.
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.
- stop path
-
Stop extended attribute support on the file system named using
path.
Extended attribute support must previously have been started.
- Xo
-
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 available
for attributes when they are written, preventing low disk space conditions
from denying attribute service.
This file should not exist before running
initattr.
- 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 initialized 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.
The kernel also includes support for automatic starting of extended
attributes on a file system at mount time once configured with
.
If the kernel is built with the
UFS_EXTATTR_AUTOSTART
option, UFS will search for a
.attribute
sub-directory of the file system root during the mount operation.
If found, extended attribute support will be started for the file system.
UFS will then search for
system
and
user
sub-directories of the
.attribute
directory for any potential backing files and enable an extended attribute
for each valid backing file with the backing file name as the attribute
name.
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
extattr_get_file(2),
getextattr(8),
extattr(9)
HISTORY
Extended attribute support was developed as part of the TrustedBSD
Project, and introduced in
FreeBSD5.0
and
NetBSD4.0.
It was developed to support security extensions requiring additional
labels to be associated with each file or directory.
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 generalized for any file system that
lacks native extended attribute support.