`elsif`

     55          if ($ct_scanout ) {
     ...          
     69          } elsif ($ct_scanout==0) {
     ...
     79          }

When you write if-elsif, ask yourself what should happen in the other cases
Sometimes the answer is 'do nothing'
- Then you omit the else clause
Sometimes the answer is 'that can never happen'
- Then you should consider adding

         else {
            die "Can't happen";
         }