Re: Brace expansion inside of command substitution - broken or is it me?

[Andreas Schwab]

Greg Wooledge <wooledg@eeg.ccf.org> writes:

> On Fri, Feb 18, 2011 at 10:32:13PM +0100, Peter Hofmann wrote:
>> 
>>  $ echo "$(echo "{1..3}")"
>>  1 2 3
>> 
>> Huh?
>
> Brace expansion is a funny thing.  My belief at the moment -- I'm sure
> someone will correct me if I'm wrong -- is that because you've got
> everything quoted up, it's all seen as one "word" by the parser.  And
> it's a word that just happens to have a brace expansion in it.  So,
> the parser expands it out something like this:
>
> $ echo "$(echo "1")" "$(echo "2")" "$(echo "3")"
>
> Counting PIDs on my sequentially-generating-PIDs OS seems to confirm that
> it's running three child processes, so that lends a tiny bit of evidence
> to my theory.

$ set -x
$ echo "$(echo "{1..3}")"
++ echo 1
++ echo 2
++ echo 3
+ echo 1 2 3
1 2 3

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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