Re: getting weird output out of 'echo' w/args
On Thu, 30 May 2013 08:53:48 +0300, Pierre Gaston pierre.gas...@gmail.com
wrote:
Missing quotes around [ ] can be nasty eg
#!/bin/bash
shopt -s nullglob # sounds a good idea!
.
.
i=0
while read a[i++]; do
echo ${a[i]} # why oh why nothing is printed!
done hello
It seems to me this has nothing to do with missing quotes around [ ], or I
don't get what you mean.
--
D.
Re: getting weird output out of 'echo' w/args
Pierre is referring to the fact that [i++] is evaluated as a glob by
the shell, the reason it doesn't work is because $i is postincremented
instead of preincremented. You can see what he means here:
$ shopt -u nullglob
$ i=0
$ while read a[++i]; do
echo ${a[i]}
done hello
hello
$ shopt -s nullglob
$ while read a[++i]; do
echo ${a[i]}
done hello
$
On 30 May 2013 16:49, Davide Brini dave...@gmx.com wrote:
On Thu, 30 May 2013 08:53:48 +0300, Pierre Gaston pierre.gas...@gmail.com
wrote:
Missing quotes around [ ] can be nasty eg
#!/bin/bash
shopt -s nullglob # sounds a good idea!
.
.
i=0
while read a[i++]; do
echo ${a[i]} # why oh why nothing is printed!
done hello
It seems to me this has nothing to do with missing quotes around [ ], or I
don't get what you mean.
--
D.
Re: getting weird output out of 'echo' w/args
On Thu, 30 May 2013 16:56:36 +0800, Chris Down ch...@chrisdown.name wrote:
Pierre is referring to the fact that [i++] is evaluated as a glob by
the shell, the reason it doesn't work is because $i is postincremented
instead of preincremented. You can see what he means here:
$ shopt -u nullglob
$ i=0
$ while read a[++i]; do
echo ${a[i]}
done hello
hello
$ shopt -s nullglob
$ while read a[++i]; do
echo ${a[i]}
done hello
$
But he was doing postincrement, so it wouldn't have worked anyway, since
the code was assigning to a[0] and printing a[1].
PS: Better put a
a=()
before each run.
--
D.
Re: getting weird output out of 'echo' w/args
That's... why I said he was unintentionally doing postincrement...
On 30 May 2013 17:04, Davide Brini dave...@gmx.com wrote:
On Thu, 30 May 2013 16:56:36 +0800, Chris Down ch...@chrisdown.name wrote:
Pierre is referring to the fact that [i++] is evaluated as a glob by
the shell, the reason it doesn't work is because $i is postincremented
instead of preincremented. You can see what he means here:
$ shopt -u nullglob
$ i=0
$ while read a[++i]; do
echo ${a[i]}
done hello
hello
$ shopt -s nullglob
$ while read a[++i]; do
echo ${a[i]}
done hello
$
But he was doing postincrement, so it wouldn't have worked anyway, since
the code was assigning to a[0] and printing a[1].
PS: Better put a
a=()
before each run.
--
D.
Re: getting weird output out of 'echo' w/args
On Thu, May 30, 2013 at 12:04 PM, Davide Brini dave...@gmx.com wrote:
On Thu, 30 May 2013 16:56:36 +0800, Chris Down ch...@chrisdown.name wrote:
Pierre is referring to the fact that [i++] is evaluated as a glob by
the shell, the reason it doesn't work is because $i is postincremented
instead of preincremented. You can see what he means here:
$ shopt -u nullglob
$ i=0
$ while read a[++i]; do
echo ${a[i]}
done hello
hello
$ shopt -s nullglob
$ while read a[++i]; do
echo ${a[i]}
done hello
$
But he was doing postincrement, so it wouldn't have worked anyway, since
the code was assigning to a[0] and printing a[1].
PS: Better put a
a=()
before each run.
--
D.
ok sorry for not having try my example, my point is that it was not
assigning to a[0] because of the nullglob and that this one can be
hard to spot
Re: getting weird output out of 'echo' w/args
On Thu, 30 May 2013 17:06:08 +0800, Chris Down ch...@chrisdown.name wrote: That's... why I said he was unintentionally doing postincrement... Doh! Indeed you said that. Apologies for reading too fast. -- D.
Re: getting weird output out of 'echo' w/args
Pierre Gaston wrote: ok sorry for not having try my example, my point is that it was not assigning to a[0] because of the nullglob and that this one can be hard to spot --- Generally don't feel good about that op except in very narrow circumstances...for exactly those types of reasons...what you can't see CAN hurt you! ;-)
Re: getting weird output out of 'echo' w/args
On 30 May 2013 17:59, Linda Walsh b...@tlinx.org wrote: Generally don't feel good about that op except in very narrow circumstances...for exactly those types of reasons...what you can't see CAN hurt you! ;-) It doesn't have anything to do with the operator, it's to do with the usage of square brackets to indicate the index.
