wp_shortlink_wp_head()

Source

File: wp-includes/link-template.php

function wp_shortlink_wp_head() {
	$shortlink = wp_get_shortlink( 0, 'query' );

	if ( empty( $shortlink ) ) {
		return;
	}

	echo "<link rel='shortlink' href='" . esc_url( $shortlink ) . "' />\n";
}