On Tue, Oct 02, 2007 at 11:49:16AM -0700, Andrew Sackville-West wrote:
> [EMAIL PROTECTED]:~$ for i in {1..3}; do echo $i; done
> 1
> 2
> 3
I don't get that result (you did say 'bash', right?):
[EMAIL PROTECTED]:~/ 0$ for i in {1..3}; do echo $i; done
{1..3}
Hmm... that was on a sarge system, with bash 2.05b-26; on a sid box,
bash 3.1dfsg-8, I do get your result.
> [EMAIL PROTECTED]:~$ TEST=3; for i in {1..$TEST}; do echo $i; done
> {1..3}
>
>
> in the first example, its obvious. In the second, $TEST gets replaced
> with 3, but then the {} doesn't get expanded. I'm sure I have to do
> some kind of wacky $({[ type thing, but I'm not able to grok it. any
> ideas?
I don't see the {1..3} construct in bash(1), so not sure how it's working
for you in the first place. Brace expansion is a different animal,
not applicable to what you're doing. But that was on sarge... On sid,
the construct is described (26% into the manpage):
A sequence expression takes the form {x..y}, where x and y are either
integers
or single characters. When integers are supplied, the expression expands
to
each number between x and y, inclusive. When characters are supplied,
the
expression expands to each character lexicographically between x and y,
inclu-
sive. Note that both x and y must be of the same type.
I think this is to taken at face value, and the parameters have to be
integers (or characters), and not variables which would expand to same.
I'm not a bash basher, but the language has its share of quirks (and
then some). I've been pushing at it quite a bit, though, and there's
a lot you can get done using bash.
> the purpose is to be able to easily update some loops in a script for
> different numbers of object to iterate over. obvious, I guess.
Maybe the for loop would be appropriate?
for (( expr1 ; expr2 ; expr3 )) ; do list ; done
First, the arithmetic expression expr1 is evaluated according to the
rules described below under ARITHMETIC EVALUATION. The arithmetic
...
Ken
--
Ken Irving, [EMAIL PROTECTED]
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