First I done it within include.inc.php and assigned the variables in template files.

But after creating smarty function i can use it like:

function smarty_function_metatag($params, &$smarty) {

if(!isset($params['tmpl'])) {
$smarty->trigger_error(“metatag: parameter ‘tmpl’ missing”);
return;
}
else if(!isset($params['ttype'])) {
$smarty->trigger_error(“metatag: parameter ‘ttype’ missing”);
return;
}

$pfile = $params['tmpl'];

switch ($params['ttype']) {

case ‘keywords’:

$array_keywords = array(
‘login’=>’Login,Extentia’,
‘faq’=>’FAQ,Extentia’,
‘news’=>’News,Extentia’,
‘contact’=>’Contact Us,Extentia’,
‘careers’=>’Careers,Extentia’,
‘forgot’=>’Forgot Password,Extentia’
);

if (array_key_exists($pfile, $array_keywords)) {
return $array_keywords[$pfile];
}

break;

case ‘description’:

$array_description = array(
‘login’=>’Login to Extentia,Extentia’,
‘faq’=>’FAQ about Extentia,Extentia’,
‘news’=>’News about Extentia,Extentia’,
‘contact’=>’Contact Us,Extentia’,
‘careers’=>’Careers at Extentia,Extentia’,
‘forgot’=>’Forgot Password,Extentia’,
);

if (array_key_exists($pfile, $array_description)) {
return $array_description[$pfile];
}

break;
}
}

Your post helped me a lot.

Thank you Viral Patel.