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From: erik@srava.sra.co.jp (Erik M. van der Poel)
Newsgroups: comp.unix.wizards
Subject: Re: file attributes
Message-ID: <1818@sranha.sra.co.jp>
Date: 28 Jun 91 06:49:31 GMT
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greywolf@unisoft.com writes:
> You said something elsewhere that (paraphrased) "/etc/magic and file(1)
> were invented by computer nerds who were worried about performance and
> disk space usage.  Disk space is cheap, and nobody worries about performance
> these days."

I pressed some of the "wrong" buttons.

Let me explain. Suppose we have a few guys working on a system that
can accept either audio or video data. They decide to add headers to
the data to identify the type of data. Their first thought is to use
"Audio" and "Video", but someone says that they don't need to use so
many characters ("It's inefficient!"), so they can just abbreviate to
"A" and "V", since audio and video is all they're worried about in
*this* system anyway.

In another part of the world, we have some guys working on a database
that can be used either for addresses or recipes. Guess what. They
chose "A" and "R", coz it was sufficient in their own little world.

So now we have ambiguity (audio "A" vs address "A"), ***IF*** the data
is not cloaked in some outer context (e.g. labelling the tape: "Acme
Inc. Audio/Video System, `Jane Goes to Kindergarten - 1995'"). In the
real world, this often works well. But sometimes it doesn't. What if
the label is glued badly and is lost? What if the human forgot to
label it?

And what about:

  "No no no! That's a DOS floppy. You can't use it like a Unix floppy.
  You need to type this special command: `blah blah blah'."

Our mothers have had just about enough of this, thank you very much.

Now maybe there is something to be said for compact representation of
metadata on disk (or anywhere else), but I think there is also
something to be said for keeping the mapping between that
representation and the readable stuff that the human sees, simple.
KISS. Perhaps we should keep it compact on disk, and readable on
tapes?

By the way, if people know of other work in this area, I would be
grateful if the info could be forwarded.


> 	- make the file command smarter

No matter how hard you work on the `file' command, it will not get
smart. We have to make the data smarter.


> What happens if we click on an object file?
> ...from another architecture?

Exactly. If we label these things, at least the system can give an
intelligent error message.


>  * Also, we need to officially register names and values, so that
>  * everyone agrees on their meaning (even in the non-Unix world).
> 
> Let's worry about this after we settle the first issue, hm?  Don't bite
> off more than you can chew.

What I have done is to think of a reasonable goal to shoot for, and to
give an outline of the migration steps to get there.

I.e. I want the information technology industry to get together to
coordinate the plan(s) and write the specifications, *before* we
implement. How many times do we have to take this lesson before we
learn it?
-
-- 
EvdP