xar (archiver)

xar

Filename extension	.xar
Uniform Type Identifier (UTI)	com.apple.xar-archive
Magic number	xar!
Latest release	1.5.3 (9 December 2009 (2009-12-09))
Type of format	archive file format
Extended from	XML, gzip
Website	code.google.com/p/xar/

Xar (short for eXtensible ARchive format) is an open source file archiver and the archiver’s file format. It was created within the OpenDarwin project and is used in Mac OS X 10.5 for software installation routines, as well as browser extensions in Safari 5.0. Xar replaced the use of gzipped pax files.

One development branch of RPM, RPM5, uses xar.

Xar is different from cpio, tar or ar in that it stores the TOC (table of contents) in the beginning of the file, making appending to an archive more complicated, but making it unnecessary to scan through the archive to extract an individual contained file. Cramfs also has the equivalent of a TOC.

External links

• Xar homepage
• Diagram of the data structure of a Xar file