How To Add One Tag to Multiple Posts?

Question

I have nearly 1500 posts in my wordpress blog. Before moving to a new design, I need to tag all these posts with one tag 'old'. How can I do this? I tried to bulk edit posts and it will always go only upto 78 posts every time I tried. I tried increasing server limits and still it won't work! How can I do this?

Answer 1

If you have the ability to use wp-cli on a bash-like shell it's a handy way to do this:

for ID in $(wp post list --post_type=post --post_status=any --field=ID); do wp post term add $ID post_tag old; done

• for ID in $(…); do starts a loop for each line of output of the internal command
• wp post list --post_type=post --post_status=any --field=ID lists all post IDs of posts. It's in fact a command line interface to WP_Query.
• wp post term add $ID post_tag old assigns the term old of the taxonomy post_tag to each post of the loop, identified by the loop variable $ID. If the term does not exist, it gets created on the first time.
• done marks the end of the loop

Answer 2

Please try this

   global $post;
   $args = array( 'posts_per_page' => -1);
   $myposts = get_posts( $args );
   foreach( $myposts as $post ) : setup_postdata($post); 
        wp_set_post_tags( the_ID(), 'old', true );
   endforeach;