Just add the following stub to the beginning of your perl program will allow your script to print to both STDOUT and results.txt. The stub works transparently so you do not have to change your print statements.

use strict;
use warnings;

# ---- add this stub to the start of your program ----
use IO::File;
use IO::Capture::Stdout;

our $capture;
BEGIN{
    $capture = IO::Capture::Stdout->new();
    $capture->start();
}

END{
  $capture->stop();
  my $f = new IO::File "results.txt", "w" or die "Can not create file"
+;
  while (defined ($_ = $capture->read())) {
    print $f "$_";
    print "$_";
  }
}

# ---- your stuff here ----
print "Test Line One\n";
print "Test Line Two\n";
print "";
print "Test Line Three\n";
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