Please put <code>-Tags around your code, so it can be displayed correctly.

<code>
#! /usr/bin/perl
# just an example
use strict;
use warnings;

print "Hello World!\n";
</code>
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Also have a look at Writeup Formatting Tips. Thanks.

Updated questions and hints which came first to my mind:

• You wrote: The script runs a system function and returns data. I am stuck, it returns nothing!

  So, what is returning nothing?
  Your CGI-Script or the system call?

• It looks like you're not using strict and warnings. Please use them, they help you to write better code.
• You use start_body and end_html from the CGI module; they already provide the opening and the closing body tags.