my %num_letters = ( a => 1,
                    e => 2,
                    g => 1,
                    i => 1,
                    n => 1,
                    r => 1,
                    t => 2,
                  );

my $charclass = join "", keys %num_letters;
my $num_chars = 0;
$num_chars += $num_letters{$_} foreach keys %num_letters;

open DICT, "<linux.words";
WORD:
while (my $word = <DICT>) {
    my %letters = %num_letters;
    chomp $word;
    next WORD unless $word =~ /^[$char_class]{$num_chars}$/;

    while (my $letter = chop($word)) {
        $letters{$letter}--;
    }
    foreach my $letter (keys %letters) {
        next WORD if ($letters{$letter} != 0);
    }
    print "Found $word\n";
}
close DICT;