Rebuild permissions for running via Drush (no batch process)

rebuild-perms.php

<?php

/**
 * @file
 * Rebuild the node access database with no php time limits.
 */

/**
 * Rebuilds the node access database (for use with drush php-script).
 *
 * This is code borrowed from Drupal core and slightly modified to run with
 * drush.
 *
 * @see node_access_rebuild()
 */
function node_access_rebuild_drush() {
  db_delete('node_access')->execute();
  // Only recalculate if the site is using a node_access module.
  if (count(module_implements('node_grants'))) {
    // Try to allocate enough time to rebuild node grants.
    drupal_set_time_limit(0);

    $nids = db_query("SELECT nid FROM {node}")->fetchCol();
    foreach ($nids as $nid) {
      $node = node_load($nid, NULL, TRUE);
      // To preserve database integrity, only acquire grants if the node
      // loads successfully.
      if (!empty($node)) {
        node_access_acquire_grants($node);
      }
    }
  }
  else {
    // Not using any node_access modules. Add the default grant.
    db_insert('node_access')
      ->fields(array(
      'nid' => 0,
      'realm' => 'all',
      'gid' => 0,
      'grant_view' => 1,
      'grant_update' => 0,
      'grant_delete' => 0,
      ))
    ->execute();
  }

  drupal_set_message(t('Content permissions have been rebuilt.'));
  node_access_needs_rebuild(FALSE);
  cache_clear_all();
}

// Start node access rebuild process.
node_access_rebuild_drush();

shrop said to run it like this:

time drush php-script rebuild-perms.php