URL-Rewriting: Peter Kröner

.htaccess

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_URI} !^/excluded-directories-like-css-or-js/
RewriteRule ^(.*)$ not-found.php [QSA,L]

not-found.php

<?php
$redirect = array(
    '/old-1.html' => '/new-resource-1.html',
);

$uri = explode('?', $_SERVER['REQUEST_URI'], 2);

if (isset($redirect[$uri[0]])) {
    // could do some funky RegEx or DB-lookups here, too :)

    $go = $redirect[$uri[0]];
    if (!empty($uri[1])) {
        $go .= '?' . $uri[1];
    }
    
    header('Moved Permanently', true, 301);
    // Note: may want to add https?://domain "required" by HTTP/1.0 - but not a *single* browser cares
    header('Location: '. $go);
    // Note: exit; would kill a fastcgid's process for no reason
    return;
}

header('Not Found', true, 404);
// do your funky 404 business