On Thu, Dec 26, 2013 at 5:34 PM, John W. Krahn <jwkr...@shaw.ca> wrote:
> Kenneth Wolcott wrote:
>>
>> Hello;
>
>
> Hello Kenneth,
>
>
>
>> I'm trying to obtain line-by-line output from a command pipe in perl.
>>
>> Unfortunately, I am firmly held to 5.8.8 version of perl on this
>> specific machine :-(
>>
>> Apparently, creating an array for my command prevents me from
>> including the final pipe symbol when trying to use the three-argument
>> form of open when using an array for my command rather than a scalar.
>>
>> code snippet #1:
>> my @cmd = ("make", "target_name", "2>&1");
>> open my $fh, @cmd, "|" or die "blah: $!\n"; fails, "Unknown open() mode
>> '5'"
>>
>> code snippet #2:
>> my @cmd = ("make", "target_name", "2>&1", "|");
>> open my $fh, @cmd or die "blah: $!\n"; fails, "Unknown open() mode '5'"
>
>
> Those won't work because the second argument for open() has to be the mode
> and it has to be a scalar value:
>
> $ perl -le'print prototype "CORE::open"'
> *;$@
>
> So the first example is:
>
> open my $fh, 3, "|" or ...;
>
> And the second example is:
>
> open my $fh, 4 or ...;
>
> Because an array in scalar context is the number of elements in the array.
>
> The correct syntax is:
>
> open my $fh, '-|', @cmd, or ...;
>
> But using a list instead of a string means that "2>&1" will be treated as a
> text string and will not effect the STDERR stream.
>
> For STDERR redirection you need to run it through the shell by using a
> string:
>
> open my $fh, 'make target_name 2>&1 |' or ...;
>
>
>
>
> John
> --
> Any intelligent fool can make things bigger and
> more complex... It takes a touch of genius -
> and a lot of courage to move in the opposite
> direction. -- Albert Einstein
Hi John, Shawn and Shlomi;
Thank you for your help.
I am successfully running now!
Thanks,
Ken Wolcott
--
To unsubscribe, e-mail: beginners-unsubscr...@perl.org
For additional commands, e-mail: beginners-h...@perl.org
http://learn.perl.org/
