wp_get_mu_plugins() │ WP 3.0.0

Retrieves an array of must-use plugin files.

The default directory is wp-content/mu-plugins. To change the default directory manually, define WPMU_PLUGIN_DIR and WPMU_PLUGIN_URL in wp-config.php.

Internal function — this function is designed to be used by the kernel itself. It is not recommended to use this function in your code.

No Hooks.

Returns

String[]. Array of absolute paths of files to include.

Usage

wp_get_mu_plugins();

Changelog

Since 3.0.0 Introduced.

wp_get_mu_plugins() code WP 6.9.1

wp-includes/load.php 
function wp_get_mu_plugins() {
	$mu_plugins = array();

	if ( ! is_dir( WPMU_PLUGIN_DIR ) ) {
		return $mu_plugins;
	}

	$dh = opendir( WPMU_PLUGIN_DIR );
	if ( ! $dh ) {
		return $mu_plugins;
	}

	while ( ( $plugin = readdir( $dh ) ) !== false ) {
		if ( str_ends_with( $plugin, '.php' ) ) {
			$mu_plugins[] = WPMU_PLUGIN_DIR . '/' . $plugin;
		}
	}

	closedir( $dh );

	sort( $mu_plugins );

	return $mu_plugins;
}