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From: Stephane CHAZELAS on 7 Feb 2010 04:45
2010-02-07, 12:58(+08), Hongyi Zhao:
> On Thu, 4 Feb 2010 12:18:29 +0000 (UTC), Stephane CHAZELAS
> <stephane_chazelas(a)yahoo.fr> wrote:
>
>>url=http://www.google.com/
>>file=myfile
>>(
>> set -C
>> ext= n=0
>> until command exec 3> "$file$ext"; do
>> ext=.$((++n))
>> done
>> exec curl "$url" >&3
>>)
>
> The above code will give annoying output like this:
>
> line 15: myfile: cannot overwrite existing file.
>
> How can I suppress these output?

until { command exec 3> "$file$ext"; } 2> /dev/null; do


--
St�phane
From: Stephane CHAZELAS on 7 Feb 2010 08:27
2010-02-07, 20:28(+08), Hongyi Zhao:
> On Sun, 7 Feb 2010 09:45:21 +0000 (UTC), Stephane CHAZELAS
> <stephane_chazelas(a)yahoo.fr> wrote:
>
>>until { command exec 3> "$file$ext"; } 2> /dev/null; do
>
> Good, thanks a lot. It does the trick.
>
> BTW, why cann't I use the following one:
>
> {until command exec 3> "$file$ext"; } 2> /dev/null; do
[...]

First, because, to be recognised as such the "{" keyword must be
followed by a blank, and then, the until is part of a "until,
do, done" sequence. {...} is group of commands, the
until,do,done would be unfinished in the {...}.

You could do:

{
until ...; do
wget...
done
} 2> /dev/null

or simply:

until ...; do
wget...
done 2> /dev/null

but then, the stderr of wget would also be redirected to
/dev/null, which is probably not what you want.


--
St�phane
From: Stephane CHAZELAS on 8 Feb 2010 12:52
2010-02-08, 15:02(+08), Hongyi Zhao:
> On Thu, 4 Feb 2010 12:18:29 +0000 (UTC), Stephane CHAZELAS
> <stephane_chazelas(a)yahoo.fr> wrote:
>
>>url=http://www.google.com/
>>file=myfile
>>(
>> set -C
>> ext= n=0
>> until command exec 3> "$file$ext"; do
>> ext=.$((++n))
>> done
>> exec curl "$url" >&3
>>)
>
> I've another issue on the above code:
>
> When I run it for the first time, I'll obtain a file with the name
> myfile. My issue is: the initial value of ext should be _.0_, so I
> think the above script should name the output as myfile.0. Any hints
> on this?


It shouldn't be that hard to figure it out by yourself.

url=http://www.google.com/
file=myfile
(
set -C
n=0
until { command exec 3> "$file.$n"; } 2> /dev/null; do
n=$(($n + 1))
done
exec curl "$url" >&3
)


--
St�phane
From: Stephane CHAZELAS on 9 Feb 2010 16:16
2010-02-09, 10:43(+08), Hongyi Zhao:
[...]
>>>>url=http://www.google.com/
>>>>file=myfile
>>>>(
>>>> set -C
>>>> ext= n=0
>>>> until command exec 3> "$file$ext"; do
>>>> ext=.$((++n))
>>>> done
>>>> exec curl "$url" >&3
>>>>)
[...]
> My poor English. In fact, I want to know why your original code will
> name the first downloaded file as myfile instead of myfile.0.
> According to my understanding, it should also name the first
> downloaded file as myfile.0 just as the below code does. Any hints?
[...]

You could try to add a "set -x" at the top, to see what happens.

--
St�phane
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