Update node field programmatically

gistfile1.txt

$query = new EntityFieldQuery();

  $query->entityCondition('entity_type', 'node')
    ->entityCondition('bundle', 'article');

  $result = $query->execute();

  if (isset($result['node'])) {
    $nodes = entity_load('node', array_keys($result['node']));

    foreach ($nodes as $node) {
      $node->field_show_feedback[LANGUAGE_NONE][0]['value'] = 1;
      $node->field_show_updated_date[LANGUAGE_NONE][0]['value'] = 1;
      node_save($node);
    }
  }