Lately I find myself re-using these handy bits of code in many of my WordPress themes. They will help you identify the name of the current template file being used in the front-end or admin. If you’re interested in checking against the current theme template then you should check out the core is_page_template() function.

In the Front-end

To get the name of the current theme template file name you need to intercept the template_include filter and save a new PHP global variable that can be referenced anywhere.

To do this add the following function to your functions.php file:

/**
 * Define current template file
 *
 * Create a global variable with the name of the current
 * theme template file being used.
 *
 * @param $template The full path to the current template
 */
function define_current_template( $template ) {
    $GLOBALS['current_theme_template'] = basename($template);

    return $template;
}
add_action('template_include', 'define_current_template', 1000);

Now that you have the global $current_theme_template variable available you need a function that can display or return the variable.

/**
 * Get Current Theme Template Filename
 *
 * Get's the name of the current theme template file being used
 *
 * @global $current_theme_template Defined using define_current_template()
 * @param $echo Defines whether to return or print the template filename
 * @return The name of the template filename, including .php
 */
function get_current_template( $echo = false ) {
    if ( !isset( $GLOBALS['current_theme_template'] ) ) {
        trigger_error( '$current_theme_template has not been defined yet', E_USER_WARNING );
        return false;
    }
    if ( $echo ) {
        echo $GLOBALS['current_theme_template'];
    }
    else {
        return $GLOBALS['current_theme_template'];
    }
}

That should do it, you can use get_current_template() to check the template name in your theme. If you want to display the filename for any reason you can pass a true value as a parameter.

In the WordPress Admin

If you want to display a specific item in the WordPress admin for a particular theme template you can get the template filename from the postmeta table in WordPress like this:

$post_id = ( isset($_GET['post']) ) ? intval($_GET['post']) : intval($_POST['post_ID']);
$template_file = get_post_meta( $post_id, '_wp_page_template', TRUE );

This can be useful to display a metabox, or maybe additional Help API items, on specific page templates in a theme. I use it all the time.