WordPress at a glance
function is not described

WP_Rewrite::using_mod_rewrite_permalinks() public WP 1.5.0

Determines whether permalinks are being used and rewrite module is enabled.

Using permalinks and index.php is not in the URL.

It's a method of the class: WP_Rewrite{}

No Hooks.

Return

true/false. Whether permalink links are enabled and index.php is NOT in the URL.

Usage

$WP_Rewrite = new WP_Rewrite();
$WP_Rewrite->using_mod_rewrite_permalinks();

Changelog

Since 1.5.0 Introduced.

Code of WP_Rewrite::using_mod_rewrite_permalinks() WP 5.5.1

<?php
public function using_mod_rewrite_permalinks() {
	return $this->using_permalinks() && ! $this->using_index_permalinks();
}