Date: Mon, 6 Mar 2000 09:55:22 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
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To: Alain Magloire <alain AT qnx DOT com>
cc: Nate Eldredge <neldredge AT hmc DOT edu>, djgpp-workers AT delorie DOT com
Subject: Re: DJGPP innovations ?????
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On Sun, 5 Mar 2000, Alain Magloire wrote:

> The Daemon thing is another step nothing special about it, you start a cron
> job or any shell scripts.

Running a program in background is easy, but finding files that are
identical (efficiently) is not.

> > But you'd also need something like copy-on-write to deal with one of the
> > files being modified, if you wanted it to be transparent.
> 
> Why do you want COW (Copy On Write)?  I would expect any modifications
> to be reflected on all the files.

I think you forget that the links were not created by the user, they
were created by a program which didn't have any clue whether the user
did or didn't want these files to be linked.  Since the user didn't
link the files, she might be mightily surprised when changing one of
them changes the other(s) as well.

For example, imagine that you have 5 different versions of the Grep
distribution on your disk ;-).  Suppose that the ``link daemon'' finds
out that all 5 versions have the same dfa.c in them, and decides to
link them together.  Then you modify dfa.c in one of the directories.
Then you want to diff it against the old version, to send diffs to
your pretesters.  Imagine your surprise when Diff reports identical
files...