Re: "until continue" causes bash to exit.

2016-07-20 Thread Dan Douglas 
On 07/19/2016 09:45 PM, Chet Ramey wrote:
> On 7/19/16 7:15 PM, Dan Douglas wrote:
>> Hi, I could reproduce this in all bash versions.
>>
>> bash -c 'set -x; until continue; do :; done; echo test1'; echo test2
>> + continue
>> test2
>>
>> I'm not actually sure whether this is supposed to work at all. Almost
>> all shells do something strange when given continue in the first
>> compound-list. E.g. ksh93 does like bash and exits, and zsh breaks
>> out of the loop.
> 
> It should probably print `test1'

That's what I figured. Playing around with this test the current bash
continues an outer loop if levels=1 while the "normal" ones (dash/mksh)
do so at levels=2. I suppose technically a script that before would
have continued the n+1th nested loop will now be off by one. (Not too
likely such a script exists or they would have noticed this.)

 $ { bash /dev/fd/9; echo; } 9<<\EOF
set -x; n=-1 levels=1
let 1 2>/dev/null || let() { IFS=, command eval test '$(($*))' -ne 0; }

until
  echo 1
  let n+=1 && break
do
  until
echo 2;
continue "$levels"
  do :
  done
  echo 3
done
EOF

+ n=-1
+ levels=1
+ let 1
+ echo 1
1
+ let n+=1
+ echo 2
2
+ continue 1
+ echo 1
1
+ let n+=1
+ break



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Re: "until continue" causes bash to exit.

2016-07-19 Thread Chet Ramey 
On 7/19/16 7:15 PM, Dan Douglas wrote:
> Hi, I could reproduce this in all bash versions.
> 
> bash -c 'set -x; until continue; do :; done; echo test1'; echo test2
> + continue
> test2
> 
> I'm not actually sure whether this is supposed to work at all. Almost
> all shells do something strange when given continue in the first
> compound-list. E.g. ksh93 does like bash and exits, and zsh breaks
> out of the loop.

It should probably print `test1', and I'll change bash to make it do that.
`continue' just sets a flag saying how many loop levels to break, but
it doesn't get reset if the loop test causes the loop to break.  I imagine
ksh93 does the same thing.  dash and mksh go into an infinite loop.

Chet
-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/



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Re: "until continue" causes bash to exit.

2016-07-19 Thread konsolebox 
On Wed, Jul 20, 2016 at 7:15 AM, Dan Douglas  wrote:
> Hi, I could reproduce this in all bash versions.
>
> bash -c 'set -x; until continue; do :; done; echo test1'; echo test2
> + continue
> test2
>
> I'm not actually sure whether this is supposed to work at all. Almost
> all shells do something strange when given continue in the first
> compound-list. E.g. ksh93 does like bash and exits, and zsh breaks
> out of the loop.
>

I see nothing wrong using continue before `do`.   I've used it a lot
of times and I never had issues with it.  It is useful when trying to
imitate `do {} until ...`, or `do {} while ...`.

However, I won't mind if it just skips checking `$?` when an explicit
control command like `continue` is used since it's more sensible that
way.  Currently, `continue` is just synonymous to `break` when used in
an `until` loop, and I find that counter-intuitive.  Four others
shells don't behave that way.

-- 
konsolebox

"until continue" causes bash to exit.

2016-07-19 Thread Dan Douglas 
Hi, I could reproduce this in all bash versions.

bash -c 'set -x; until continue; do :; done; echo test1'; echo test2
+ continue
test2

I'm not actually sure whether this is supposed to work at all. Almost
all shells do something strange when given continue in the first
compound-list. E.g. ksh93 does like bash and exits, and zsh breaks
out of the loop.



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