You're passing data on the command line without any quoting. In case it doesn't look like anything malicious was attempted, this will only get the first word into your script.

In other words: make your whole text your first parameter. Quote it.

If on Unix — and it looks like you are — then take a look at String::ShellQuote. It looks to me like that's a safe catch-all way to get your whole string into your script.

Another way to make sure your data gets though uncorrupted, is to use piping. Make the data come through the child script's STDIN. Thus, replace

    system("perl prn_to_file.pl $param1 > ../results/output.txt");
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with

    open SYSTEM, "| perl prn_to_file.pl > ../results/output.txt");
   print SYSTEM $param1;
   close SYSTEM;
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Untested, but basically, something like that.

And finally, I think nothing works just because your user has no rights to write to the "../results" directory — I bet the CGI isn't run under the user name "myname". That's what permissions "drwxrwxr-x" tell me: no "w" for "world".