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Re: Question on $@ vs $@$@


From: Steffen Nurpmeso
Subject: Re: Question on $@ vs $@$@
Date: Wed, 28 Aug 2024 02:03:54 +0200
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Robert Elz wrote in
 <14146.1724799924@jacaranda.noi.kre.to>:
 |    Date:        Tue, 27 Aug 2024 22:02:34 +0200
 |    From:        Steffen Nurpmeso <steffen@sdaoden.eu>
 |    Message-ID:  <20240827200234.95X76_wN@steffen%sdaoden.eu>
 |
 |
 ||   Any character in IFS delimits a field, adjacent IFS whitespace
 ||   characters are then ignored.
 |
 |Not quite.   Any sequence of any amount of IFS whitespace, and no
 |more than one other IFS character delimits a field.

That confuses me again, unfortunately i got a bug report and
distracted.  I mean, i would

1. skip leading whitespace anyhow (IFS or not, which
   is a "documented bug" here i would say),
   for the shell this would be: leading IFS whitespace,

2. pass by none-to-many non-IFS bytes, the "field data", then

3.
   a. if there is a non-IFS-whitespace character:
      - delimit the field, even with empty "field data",

   b. if there is a IFS-whitespace character:
      - delimit the field only with non-empty "field data",

4. skip trailing (new leading) (IFS-) whitespace

 || To the contrary i would now say that with a non-default non-empty
 || $IFS only IFS characters that are not also IFS whitespace create
 || empty fields.
 |
 |The preconditions there are irrelevant.
 |Only IFS chars that are not IFS whitespace create empty fields.

Yes.

 |Where IFS is empty, there are no IFS chars, hence nothing delimits
 |a field.   When IFS is unset (default case) it consists of $' \t\n'
 |(there is no difference whatever, for field splitting, or "$*" for
 |that matter) between an unset IFS and IFS=$' \t\n'
 |
 |||You have to look at the definition of IFS whitespace.
 || Already forgotten at that point.
 |
 |Unfortunately, when reading the standard, you cannot forget a
 |single word of it.  Everything (normative) applies.

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)



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