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Asking how to read tar tapes

    Date: Fri, 20 Jul 90 12:40:48 EDT
    From: djs@stdb.jhuapl.edu (David J. Scheerer)

    Could someone please tell me if there is a way to read tar tapes
    from a Symbolics?  E-mail to me or post to SLUG.  Thanks!

    - David J. Scheerer  [djs@stdb.jhuapl.edu]  (301) 792-5000 x3144, 3440 -
    - JHU/Applied Physics Lab 7-113 Johns Hopkins Rd. Laurel, MD 20723     -
In Genera 8.0 there is a command :READ TAR TAPE that works if the files you want
to retrieve are character files.  There is a distinction on the Lispm, and of
course none on Unix, so whether that assumption is correct or not can't be told
from the data on the tape.  Obviously executable binaries are probably not useful
on a Lispm, but there are many other binary files (e.g. images, various data
files) which are useful, so I consider this a deficiency.  There are discussions
going on right now on how to improve this for a later release.

The source code for READ TAR TAPE is distributed and if you want to read
ONLY binary data, it is fairly trivial to make the changes (I can send you a
private patch if you want).

If you want to read a tape that has mixed character and binary files, you can
either make two passes through the tape (loading the binary patch in the middle
and selecting the character files first) or modify the code to ask which way
you want any particular file.  

(BTW, there is a functional interface for reading tar FILES [as opposed to tapes];
I'm lobbying for a future release to support this at the command level, in addition
to allowing reading of compressed tar files.  Of course, I'm not guaranteeing that
these enhancements will make it into Genera or when.)