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From: malte@TechFak.Uni-Bielefeld.DE
To: rc@hawkwind.utcs.toronto.edu
Subject: Re: Thoughts on a builtin read
Date: Tue, 21 Sep 1993 11:56:15 -0400	[thread overview]
Message-ID: <9309211556.AA20736@dahlie.techfak.uni-bielefeld.de> (raw)

[ rsalz@osf.org wrote ]:
    Anyhow, let's take a look at your idea.  That is,
    hould set $status to the exit value of foobar.  What should
    set $status to?  Leave it unchanged?  What about
    if the directory is empty?  And if it isn't? What about
    when /foo doesn't exist?

Yes, an assignment leaves the status unchanged. Your file name expansion 
examples are just a shorthand for
	x = `{ glob /foo/* }	# glob == echo

Currently, neither "x=*" nor "x=`{ glob *}" sets $status to some reasonable
value, it is just 0 -- always!

    You are making a simple shell very complicated, don't you think?

Complicated is your word for it, I'd rather call it more usable. I have
frequently had the problem to distinguish between a failed backquote
command and a command producing no output. There may be better solutions then
	x = `{ foo || echo '!@#$%^&*()' }
	if( ~ $x '!@#$%^&*()' )
but it seems to me to be a FAQ. The person who started this thread had
just this problem. I don't mean to offend anybody, but I have the impression
that because Tom Duff invented this shell there can't be anything wrong. But
if one takes a closer look, one sees quite a few sh'isms still in it, e.g
shift. I think rc in its original form and in its current form is an excellent
point to start a shell project. This is why I post all this to this list
and have it discussed instead of just implementing it for myself. Be assured
though, that I very much appreciate different opinions.

Back to the read problem: Currently there is no builtin which assigns
a value to a variable ( except for the special variables of course ).
There's been a discussion on shift shifting arbitrary lists with the
proposed syntax being "shift x 2" probably because "x = `{ shift x 2 }"
isn't too elegant. If this makes its way into rc, I don't mind if read
expects a variable as a command line parameter. But since I don't care
if some functionality is built into the shell, I'd prefer the
backquote substitution solution.


             reply	other threads:[~1993-09-21 15:56 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
1993-09-21 15:56 malte [this message]
1993-09-21 17:02 ` Chris Siebenmann
  -- strict thread matches above, loose matches on Subject: below --
1993-09-22 17:18 Steve_Kilbane
1993-09-21 17:26 Arnold Robbins
1993-09-21 17:11 rsalz
1993-09-21 16:58 Arnold Robbins
1993-09-21 16:52 gjv%atlas%cesar
1993-09-21 16:36 Byron Rakitzis
1993-09-21 16:50 ` Chris Siebenmann
1993-09-21 15:54 Tom Culliton x2278
1993-09-21 15:15 Alan Watson
1993-09-21 15:09 rsalz
1993-09-21 14:33 malte
1993-09-21 14:20 rsalz
1993-09-21  6:51 malte
1993-09-21 14:19 ` Chris Siebenmann
1993-09-20 22:11 Tom Culliton x2278

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