wp_install_maybe_enable_pretty_permalinks(): bool

496function wp_install_maybe_enable_pretty_permalinks() {497	global $wp_rewrite;498 499	// Bail if a permalink structure is already enabled.500	if ( get_option( 'permalink_structure' ) ) {501		return true;502	}503 504	/*505	 * The Permalink structures to attempt.506	 *507	 * The first is designed for mod_rewrite or nginx rewriting.508	 *509	 * The second is PATHINFO-based permalinks for web server configurations510	 * without a true rewrite module enabled.511	 */512	$permalink_structures = array(513		'/%year%/%monthnum%/%day%/%postname%/',514		'/index.php/%year%/%monthnum%/%day%/%postname%/',515	);516 517	foreach ( (array) $permalink_structures as $permalink_structure ) {518		$wp_rewrite->set_permalink_structure( $permalink_structure );519 520		/*521		 * Flush rules with the hard option to force refresh of the web-server's522		 * rewrite config file (e.g. .htaccess or web.config).523		 */524		$wp_rewrite->flush_rules( true );525 526		$test_url = '';527 528		// Test against a real WordPress post.529		$first_post = get_page_by_path( sanitize_title( _x( 'hello-world', 'Default post slug' ) ), OBJECT, 'post' );530		if ( $first_post ) {531			$test_url = get_permalink( $first_post->ID );532		}533 534		/*535		 * Send a request to the site, and check whether536		 * the 'X-Pingback' header is returned as expected.537		 *538		 * Uses wp_remote_get() instead of wp_remote_head() because web servers539		 * can block head requests.540		 */541		$response          = wp_remote_get( $test_url, array( 'timeout' => 5 ) );542		$x_pingback_header = wp_remote_retrieve_header( $response, 'X-Pingback' );543		$pretty_permalinks = $x_pingback_header && get_bloginfo( 'pingback_url' ) === $x_pingback_header;544 545		if ( $pretty_permalinks ) {546			return true;547		}548	}549 550	/*551	 * If it makes it this far, pretty permalinks failed.552	 * Fallback to query-string permalinks.553	 */554	$wp_rewrite->set_permalink_structure( '' );555	$wp_rewrite->flush_rules( true );556 557	return false;558}