Just as an aside (very tangentially related), if you've got (say) external code in a module you can't easily change with printfs you need to capture you could always locally set STDOUT to a filehandle opened on a scalar ref.

#+begin_src perl :results output drawer
  use strict;
  use 5.026;

  my $output;
  do {
    open( my $fh, q{>}, \$output ) or die "Problem redirecting to scal
+ar: $!\n";
    local( *STDOUT ) = $fh;

    ## pretend this bit is in some 3rd party module you can't modify
    printf( "This should go %s", qq{elsewhere} );
    };

  say qq{\$output is '$output'};
#+end_src

#+RESULTS:
:results:
$output is 'This should go elsewhere'
:end:
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