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.

For some simple examples of how to use it, see the QuickStart.

Tarix is designed to work as a compression filter for tar with the
--use-compress-program option.  It is capable of doing gzip/zlib compression
on the archive while it indexes it.  When doing so, it does some special
work so that it is still possible to seek in the compressed archive. 
Tarix's compressed output is compatible with gzip, but an archive compressed
by gzip will not have the seeking capabilities tarix needs.

Because you cannot pass options with --use-compress-program, tarix will look
for options in the TARIX environment variable in addition to the command
line.  The QuickStart shows examples of how to do this.

Web Page: https://github.com/fastcat/tarix/
Alternate sites:
  https://fastcat.org/software/
  http://reprehensible.net/~cheetah/tarix/