$ perl -le '@f = glob("*.mp3"); push @{$f[/ad/]}, $_ foreach @f; use Data::Dumper; print Dumper(\@f, \@{"bad.mp3"}, \@{"bar.mp3"})'
$VAR1 = [
          'bad.mp3',
          'bar.mp3',
          'foo.mp3',
          'moo.mp3'
        ];
$VAR2 = [
          'bar.mp3',
          'foo.mp3',
          'moo.mp3'
        ];
$VAR3 = [
          'bad.mp3'
        ];