[tpm] How to pipe variable content to shell scripts

Shlomi Fish shlomif at shlomifish.org
Tue Jan 21 10:42:28 PST 2014

Hi Antonio,

On Tue, 21 Jan 2014 12:29:43 -0500
Antonio Sun <tpm.ats at spamgourmet.com> wrote:

> Hi,
> I have a script that works on xml content. A thousand time simplified
> version is:
>  xml_output | perl -n000e 's,(?<=">)(.*?)(?=</HttpBody>),`echo $1 | wc
> -c`,eg; print'

why are you doing `echo $1 | wc -c` instead of simply doing «length($1)»?
Also see http://perl-begin.org/topics/security/code-markup-injection/ and
http://perl-begin.org/tutorials/bad-elements/#calling-the-shell-too-much .

> I.e., I need to pipe the matching string ($1, content between tag HttpBody)
> to an external program via shell. As you can tell, if the matching content is
> too big for shell parameter length, my script will fail.
> I *have to* process the matching string via the external program. Is there
> any way I can get around this?

If you need to do so use https://metacpan.org/pod/IPC::Run or
https://metacpan.org/pod/String::ShellQuote or
https://metacpan.org/pod/IPC::System::Simple .


	Shlomi Fish

Shlomi Fish       http://www.shlomifish.org/
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