How to change meta data(robots meta tag) from controller in Magento ? Is there a way to access head block from controller and append new value in it ?
Yes definitely you can use the following code in your controller action method:
$this->getLayout()->getBlock('head')->setTitle($this->__('My Custom Meta Title'));
You just need to ensure that this code is called after
$this->loadLayout(); and before
setDescriptionto set the meta description
setKeywordsto set the meta keywords