This Drush command opens an interactive PHP shell for a Drupal site. It uses the Readline library if available.
This command is useful for quickly testing code snippets, making DB queries, and so forth. For more robust scripts, use the php-script or write a custom drush command.
Example usage:
> drush php-cli
>> $u = user_load(1);
(stores user object into variable $u)
>> print_r($u);
(prints user object)
>> $count = db_result(db_query("SELECT COUNT(*) FROM users"));
(stores value into variable $count)
The PHP_Shell library is available here: http://jan.kneschke.de/projects/php-shell