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Re: 'For' loops with empty 'in' expansions no longer work.


From: Chet Ramey
Subject: Re: 'For' loops with empty 'in' expansions no longer work.
Date: Mon, 22 Apr 2002 10:05:52 -0400

> Machine Type: i386-redhat-linux-gnu
> 
> Bash Version: 2.05
> Patch Level: 8
> Release Status: release
> 
> Description:
>       In bash2 versions up to 2.04, a loop of the form
> 
>               for i in $WORDS
>               do
>                       <stuff>
>               done
>       
>       would not execute the loop body if $WORDS expanded to nothing.
>       In version 2.05, this situation generates a syntax error.
> 
>       The bash documentation (info page) indicates that the 2.04
>       behaviour is correct and the most recent change is incorrect.
> 
>       The previous behaviour was certainly more useful, since the loop
>       body could be executed only if there were arguments to work with
>       (e.g. in the case where <stuff> is "gcc $i" -- this clearly
>       makes no sense if $i is empty).
> 
> Repeat-By:
> 
>       for i in ; do echo foo; done

This is not at all the same thing as your example above, and should be a
syntax error according to the (now old) POSIX.2 grammar.

POSIX.2 changed the grammar, and bash-2.05a no longer requires a list of
words after the `in'.



-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
( ``Discere est Dolere'' -- chet)

Chet Ramey, CWRU    address@hidden    http://cnswww.cns.cwru.edu/~chet/



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