I went to the Code Catacombs to post my script for finding cryptographic matches for a given pattern, and discovered that merlyn had already posted pat. (Some time ago, in fact. :) merlyn's script also has the nice feature of allowing the user to specify literal letters, which appear unchanged in the matching word(s).

By the way, depending on your system, /usr/dict/words may not be very useful at all for solving cryptograms. /usr/dict/words was originally intended for use with the spell utility, which does stemming to guess if a word is spelled correctly. Thus, /usr/dict/words may contain only root words and irregular forms, i.e. talk but not talks, talked, or talking.

I've been working on my own program in Perl to solve cryptograms. I recommend the ENABLE word list.

P.S. Oh, what the heck. My code works somewhat differently from merlyn's, so I'll go ahead and post it here. I expect his use of regexes will be faster than my use of split and hashes, though.

#!/usr/local/bin/perl -w

use strict;
use Getopt::Std;

use vars qw($opt_w);

getopts('w:') || die "Bad options.\n";

my $dict = $opt_w || 'wordlist';

open(DICT, $dict) or die "Can't open $dict: $!\n";

my $crypto = shift;

my $match = &crypto_canon($crypto);

while (<DICT>) {
    chomp;

    next if length $match != length $_;
    next if $match ne &crypto_canon($_);

    print "$_\n";
}

sub crypto_canon {
    my($word) = @_;

    my $canon;
    my %letters;
    my $next = 'a';

    foreach (split //, $word) {
        if ($_ !~ /[a-z]/) {
            $canon .= $_;
            next;
        } elsif (not exists $letters{$_}) {
            $letters{$_} = $next++;
        }
        $canon .= $letters{$_};
    }
    $canon;
}
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