How to save Log in a text file using Zend Framework

We can do that using Zend Log & Zend Log Writer Stream classes.
Ex:
 $logText        =    'TEST TO LOG THE STRING IN TEXT FILE';
 $stream        =    fopen('/var/www/log/path/filename.txt', 'a');
 if( $stream ){
   $writer        =    new Zend_Log_Writer_Stream($stream);
   $logger        =    new Zend_Log($writer);
   $logger->log($logText,Zend_Log::INFO);
  }

How to redirect in Zend Framework without using standard redirect function

If you want to use Zend redirect without using standard redirect function from controller, you can use the below code in any of the plugin or function.
 $redirector = Zend_Controller_Action_HelperBroker::getStaticHelper('redirector');
  $redirector->gotoUrl('/profile/change-password/')->redirectAndExit();

How to get HTTP REFERER value in Zend Framework

You can get that directly in Controller using the below code
     $requestUri    =    $this->getRequest()->getServer('HTTP_REFERER');
 If you want to get that outside of Controller you can use the Zend Front Contorller class
 $requestUri    =    Zend_Controller_Front::getInstance()->getRequest()->getRequestUri();