tarix is a program for indexing tar archives so that selective extraction
can be done rapidly, especially on slow devices like tape drives, providing
that you can seek to arbitrary locations (at least on 512 byte boundaries)
within the tar archive.

Tarix is designed to work as a compression filter for tar with the
--use-compress-program option.  Tarix can either pass the tar archive
straight through, or it can compress the archive using zlib on the way
through.  Note that tarix does special things when using zlib to enable
random access when extracting.  A regular gzip'd tar archive will not be
usable at extraction time without first uncompressing it.

Because of how tar invokes compress programs, options are generally accepted
through environment variables.  For manual usage, however, tarix can accept
normal command line options.

Tarix's output format is geared for simplicity and ease of use in a recovery
mode.  For those reasons, it is a simple text format.  The goal behind this
is to allow tarix's indexes to be used from even a basic recovery disk. 
Using tarix's indexes requires only grep, sed, dd, and tar for basic usage. 
tarix itself can use the index for fast extraction without convoluted usage
of grep, sed, and dd.  When working with zlib compressed archives, random
access extraction will require tarix because the available tools generally
do not have the required seeking support.

Currently tarix targets GNU tar archives.  It does currently try and support
any of the fancier GNU tar extensions, such as sparse files and such,
although it may work with them anyways, since it only looks at the file
headers within the archive.  It can handle GNU's format for very long file
names, though it will probably barf on filenames more than 511 chars long. 
It should also be able to handle standard POSIX archives.

Do not put newlines in your filenames, it *WILL* break tarix's output
format (and probably lots of other things too).

It is unknown if it will work with other tar programs, but the author would
be very interested to hear about success or failure with them.  If
supporting other formats does not excessively complicate tarix, it will be
added if and when the necessary information about the format differences is
provided to the author.

Tarix's format uses 32 bit unsigned integers to count 512 byte blocks, so it
should be able to handle archives up to 2 terabytes.

Web Page: http://sf.net/projects/xtar/
Alternate sites:
  http://fastcat.org/software/
  http://reprehensible.net/~cheetah/tarix/
