Get all the multisite paths from Drush.

multsite_paths.drush.inc

<?php
/**
 * Get Local Paths.
 *
 * Returns an array of full paths to the local Drupal sites.
 *
 * @return array Array of full paths for local sites or an empty array.
 */
function _multisite_get_path(){

  $sites_record = (array) drush_sitealias_get_record('@sites');
  $self_record = (array) drush_sitealias_get_record('@self');

  if (drush_valid_drupal_root($self_record['root'])){

    foreach ($sites_record['site-list'] as $key => $value) {
      $sites[$key] = str_replace('#', '/'.$sites_record['#name'].'/', $value);
    }
  }

  return $sites;
}