wp_not_installed() WordPress Function

function wp_not_installed() {
	if ( is_multisite() ) {
		if ( ! is_blog_installed() && ! wp_installing() ) {
			nocache_headers();

			wp_die( __( 'The site you have requested is not installed properly. Please contact the system administrator.' ) );
		}
	} elseif ( ! is_blog_installed() && ! wp_installing() ) {
		nocache_headers();

		require ABSPATH . WPINC . '/kses.php';
		require ABSPATH . WPINC . '/pluggable.php';

		$link = wp_guess_url() . '/wp-admin/install.php';

		wp_redirect( $link );
		die();
	}
}
Uses	Description
wp-includes/load.php:wp_installing()	Check or set whether WordPress is in “installation” mode.
wp-includes/l10n.php:__()	Retrieve the translation of $text.
wp-includes/pluggable.php:wp_redirect()	Redirects to another page.
wp-includes/load.php:is_multisite()	If Multisite is enabled.
wp-includes/functions.php:wp_guess_url()	Guess the URL for the site.
wp-includes/functions.php:wp_die()	Kills WordPress execution and displays HTML page with an error message.
wp-includes/functions.php:is_blog_installed()	Determines whether WordPress is already installed.
wp-includes/functions.php:nocache_headers()	Set the headers to prevent caching for the different browsers.