The
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 an 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.
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
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.
Extended attribute support was developed as part of the TrustedBSD Project,
and introduced in
Fx 5.0 .
It was developed to support security extensions requiring additional labels
to be associated with each file or directory.
