WordPress Plugin to update WordPress posts in bulk, changing any post field, not just the ones WP admin allows. Customize the code inside the foreach loop as desired. Save this in a file, place it in your plugins directory and activate it. The changes will run on activation. Delete the plugin after the change. Article on this here: http://kakoma…

WordPressPlugin-Update posts in bulk

<?php
/**
  * Plugin Name:       Post Bulk Update
  * Description:       On activation, I'll updates certain fields of your posts at once. Can't wait!
  * Version:           1.0.0
  * Author:            Your name here
  * License:           GPL-2.0+
  * License URI:       http://www.gnu.org/licenses/gpl-2.0.txt
  *  */
if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly 
 
if ( ! class_exists( 'MyPlugin_BulkUpdatePosts' ) ) : 
 
class MyPlugin_BulkUpdatePosts {          
 
public function __construct(){
      register_activation_hook( __FILE__, array( $this, 'do_post_bulk_update' ) );//Run this code only on activation
}          
 
//Put your code in this function
public function do_post_bulk_update(){
    $posts_to_update = get_posts('cat=x&showposts=1000');//Retrieve the posts you are targeting. CHANGE THIS to retrieve the posts you want to update
    foreach ( $posts_to_update as $update_this_post ):
           $update_this_post->post_title = 'Post Prefix: '.$update_this_post->post_title;//The post field you are updating.
           wp_update_post( $update_this_post );
    endforeach;
 }
 
}
endif;
 
return new MyPlugin_BulkUpdatePosts();