since you're building this data structure manually, you have the ability to keep it in a config file, and do or eval it when neccessary. if you have unique values, for instance HTTP_USER_AGENT, you can use this as the key to the hash. i have an example below.

if you don't have unique values, or require some combination of values for a unique key, you'll have to modify the data structure a little bit, to make sure your keys are unique.

in any case, a read through perldsc will give you insight on working with complex data structures like hashes of hashes.

my %passed = { 
    "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)"=> { 
        NAME        =>    "MS Internet Explorer",
        VERSION     =>    "5.0",
        PLATFORM    =>    "NT",
        # more specialized info here
    }, 
    # more HTTP_USER_AGENT strings here...
    URI_REDIRECT => 'http://passaddress/', 
};

# if $test_key is the unique browser identifier you're looking for
# you may print like...
my $message = join( ' ', 
    $passed{$test_key}->{NAME}, 
    $passed{$test_key}->{VERSION}, '/',
    $passed{$test_key}->{PLATFORM),
    # etc.
);
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~Particle ;Þ