if (open(OUTFILE, ... )) {
  push(@file_did_save, $filename);
} else {
  push(@did_not_save, $filename . ' ' . $!);
}

##</code><code>##

$config{'image_upload_dir'}.$fntwo

##</code><code>##

$config{'image_upload_dir'} . '/' . $fntwo

##</code><code>##

use File::Spec::Functions;
catfile($config{'image_upload_dir'}, $fntwo)