srawls, your .= solution doesn't work in this case: http://www.something.com/something (one of the formats the poster was expecting). Trying, perhaps a conditional statement would fix your solution:

if($address =~ m!/$!) { $address .= 'index.html' }
                 else { $address .= '/index.html' }
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As per srawls' last solution offered, you can add a simple regex check to the condition clause, as well, if only certain $address variables are desired.