Ultrix (and other) tar formats

[Guy Harris]

> I have found that BSD tar is *not* identical to System V tar format,
> this gives me a great problem, since I have many source tapes of BSD
> that I would like to read on a System V!

The BSD "tar" format is a superset of the V7/S3/S5 "tar" format.  It puts
out "funny" entries for directories; other "tar"s don't put out any
information about directories.  Reading a BSD "tar" tape on a non-BSD system
causes some warning messages about the directory entries, but all the files
and containing directories are created as before.  (Of course, if it's a
4.2BSD "tar" tape with symbolic links, it won't work if your system doesn't
support symbolic links.)

If the "tar" tape was written with the default block size on a BSD system
(20*512 bytes), you may have trouble reading it on 3B20s with the loser tape
controller or other such machines which can't support large block sizes on
tape.  Otherwise, just mount up the tar tape and start reading.

	Guy Harris