NAME

xattr — display and manipulate extended attributes

SYNOPSIS

DESCRIPTION

The xattr command can be used to display, modify or remove the extended attributes of one or more files, including directories and symbolic links. Extended attributes are arbitrary metadata stored with a file, but separate from the filesystem attributes (such as modification time or file size). The metadata is often a null-terminated UTF-8 string, but can also be arbitrary binary data.

One or more files may be specified on the command line. For the first two forms of the command, when there are more than one file, the file name is displayed along with the actual results. When only one file is specified, the display of the file name is usually suppressed (unless the -v option described below, is also specified).

In the first form of the command (without any other mode option specified), the names of all extended attributes are listed. Attribute names can also be displayed using “ls -l@”.

In the second form, using the -p option (“print”), the value associated with the given attribute name is displayed. Attribute values are usually displayed as strings. However, if nils are detected in the data, the value is displayed in a hexadecimal representation.

The third form, with the -w option (“write”), causes the given attribute name to be assigned the given value.

The fourth form, with the -d option (“delete”), causes the given attribute name (and associated value), to be removed.

In the fifth form, with the -c option (“clear”), causes all attributes (including their associated values), to be removed.

Finally, the last form, with either the -h or --help option, displays a short help message and exits immediately.

OPTIONS

-l

By default, the first two command forms either displays just the attribute names or values, respectively. The -l option causes both the attribute names and corresponding values to be displayed. For hexadecimal display of values, the output is preceeded with the hexadecimal offset values and followed by ASCII display, enclosed by “|”.

-r

If a file argument is a directory, act as if the entire contents of the directory recursively were also specified (so that every file in the directory tree is acted upon).

-s

If a file argument is a symbolic link, act on the symbolic link itself, rather than the file that the symbolic link points at.

-v

Force the file name to be displayed, even for a single file.

-x

Force the attribute value to be displayed in the hexadecimal representation.

The -w option normally assumes the input attribute value is a string. Specifying the -x option causes xattr to expect the input in hexadecimal (whitespace is ignored). The xxd(1) command can be used to create hexadecimal representations from existing binary data, to pass to xattr.

EXIT STATUS

The xattr command exits with zero status on success. On error, non-zero is returned, and an error message is printed to the standard error. For system call errors, both the error code and error string are printed (see getxattr(2), listxattr(2), removexattr(2) and setxattr(2) for a complete list of possible error codes).

Some attribute data may have a fixed length that is enforced by the system. For example,

% xattr -w com.apple.FinderInfo 0 foo
xattr: [Errno 34] Result too large: 'foo'

The com.apple.FinderInfo attribute must be 32 bytes in length.

EXAMPLES

This example copies the com.apple.FinderInfo attribute from the /usr directory to the MyDir directory:

% xattr -px com.apple.FinderInfo /usr
00 00 00 00 00 00 00 00 40 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
% xattr -l MyDir
% xattr -wx com.apple.FinderInfo \
  "`xattr -px com.apple.FinderInfo /usr`" MyDir
% xattr -l MyDir
com.apple.FinderInfo:
00000000  00 00 00 00 00 00 00 00 40 00 00 00 00 00 00 00  |........@.......|
00000010  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  |................|
00000020

SEE ALSO

ls(1), xxd(1), getxattr(2), listxattr(2), removexattr(2), setxattr(2)