"php -S"

PHP
cd path/to/your/app
php -S localhost:8000<?php
echo "Hello world";

// ... more code

echo "Last statement";

// the script ends here with no PHP closing tag

// Example usage for: Null Coalesce Operator
$action = $_POST['action'] ?? 'default';

// The above is identical to this if/else statement
if (isset($_POST['action'])) {
    $action = $_POST['action'];
} else {
    $action = 'default';
}
Source

Also in PHP: