use Algorithm::Loops qw( NextPermute );

my $word = 'tool';

my @list = sort ' ', $word =~ /(.)/g;
my $last_word = '';
while (NextPermute(@list)) {
   my $new_word = join('', @list);
   $new_word =~ s/ .*//;
   next if ($new_word eq $last_word);
   $last_word = $new_word;
   print($new_word, $/);
}