Sometimes you may only need to run a few PHP commands after bootstrapping Drupal. For example, to view the value of a server variable, to programmatically submit a form, and to print the output of a very complex database query that needs some placeholders. Normally, to achieve this, you would copy index.php to a temporary file, remove the line that invokes the controller and type in your own code. Drush helps you do this more easily and securely through the commands php-eval and php-script.