PHP built in server and .htaccess mod rewrites

Here's the router that I use for the builtin php webserver that serves assets from the filesystem if they exist and otherwise performs a rewrite to an index.php file.

Run using:

php -S localhost:8080 router.php

router.php:

<?php

chdir(__DIR__);
$filePath = realpath(ltrim($_SERVER["REQUEST_URI"], '/'));
if ($filePath && is_dir($filePath)){
    // attempt to find an index file
    foreach (['index.php', 'index.html'] as $indexFile){
        if ($filePath = realpath($filePath . DIRECTORY_SEPARATOR . $indexFile)){
            break;
        }
    }
}
if ($filePath && is_file($filePath)) {
    // 1. check that file is not outside of this directory for security
    // 2. check for circular reference to router.php
    // 3. don't serve dotfiles
    if (strpos($filePath, __DIR__ . DIRECTORY_SEPARATOR) === 0 &&
        $filePath != __DIR__ . DIRECTORY_SEPARATOR . 'router.php' &&
        substr(basename($filePath), 0, 1) != '.'
    ) {
        if (strtolower(substr($filePath, -4)) == '.php') {
            // php file; serve through interpreter
            include $filePath;
        } else {
            // asset file; serve from filesystem
            return false;
        }
    } else {
        // disallowed file
        header("HTTP/1.1 404 Not Found");
        echo "404 Not Found";
    }
} else {
    // rewrite to our index file
    include __DIR__ . DIRECTORY_SEPARATOR . 'index.php';
}

It is not possible to handle .htaccess using PHP's built-in webserver (it is not relying on apache, it is implemented entirely in PHP's core). However, you can use router script (described here: http://php.net/manual/en/features.commandline.webserver.php).

E.g. php -S localhost -S localhost:8080 router.php

We're currently working with legacy projects and I came accross with the same problem. Based on @Caleb's answer, we managed to add a few more controls:

1. Route the request to an old htaccess router (url.php on the example below);
2. Work with query string;
3. Change the current directory to work with PHP includes;
4. Plus: naming to server.php to match Laravel's PHP Builtin router.

Just type in the cmd: php -S localhost:8888 server.php

chdir(__DIR__);
$queryString = $_SERVER['QUERY_STRING'];
$filePath = realpath(ltrim(($queryString ? $_SERVER["SCRIPT_NAME"] : $_SERVER["REQUEST_URI"]), '/'));
if ($filePath && is_dir($filePath)){
    // attempt to find an index file
    foreach (['index.php', 'index.html'] as $indexFile){
        if ($filePath = realpath($filePath . DIRECTORY_SEPARATOR . $indexFile)){
            break;
        }
    }
}
if ($filePath && is_file($filePath)) {
    // 1. check that file is not outside (behind) of this directory for security
    // 2. check for circular reference to server.php
    // 3. don't serve dotfiles
    if (strpos($filePath, __DIR__ . DIRECTORY_SEPARATOR) === 0
        && $filePath != __DIR__ . DIRECTORY_SEPARATOR . 'server.php' 
        && substr(basename($filePath), 0, 1) != '.'
    ) {
        if (strtolower(substr($filePath, -4)) == '.php') {
            // change directory for php includes
            chdir(dirname($filePath));

            // php file; serve through interpreter
            include $filePath;
        } else {
            // asset file; serve from filesystem
            return false;
        }
    } else {
        // disallowed file
        header("HTTP/1.1 404 Not Found");
        echo "404 Not Found";
    }
} else {
    // rewrite to our router file
    // this portion should be customized to your needs
    $_REQUEST['valor'] = ltrim($_SERVER['REQUEST_URI'], '/');
    include __DIR__ . DIRECTORY_SEPARATOR . 'url.php';
}