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 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.

extattrctl stop /

Stop extended attributes on the root file system.

HISTORY

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

AUTHORS

Robert N M Watson