Bulk move posts with various tag to a category with WP-CLI

browser-console.js

// To run in the browser console to get the list of ids to copy and paste to the shell script 
function extractIdsFromTable() {
   const rows = document.querySelectorAll('tr');

   let idValues = [];

   rows.forEach((row) => {
     const idCell = row.querySelector('td.term_id');

     if (idCell) {
       idValues.push(idCell.textContent.trim());
     }
   });

   console.log(idValues.join(' '));
 }

 extractIdsFromTable();

bulk-move.php

<?php
// Bulk move CLI, it is based on the bulk-move plugin code
// wp eval-file ./bulk-move.php --skip-plugins --skip-themes 27704 46900
// Where the first id is the tag id and the second is the category tag
$wp_query = new WP_Query();

$old_tag = $args[0];
$new_cat = $args[1];

$posts = $wp_query->query( array(
    'tag__in'   => $old_tag,
    'post_type' => 'post',
    'nopaging'  => 'true',
));

echo "Found " . count($posts) . " posts\n";

$i = 0;
foreach ( $posts as $post ) {
    $i++;
    $current_cats = wp_get_post_categories( $post->ID );
    if (!in_array($new_cat, $current_cats)) {
        if ( -1 !== $new_cat ) {
            // Add to existing categories.
            $current_cats[] = $new_cat;
        }

        if ( count( $current_cats ) == 0 ) {
            $current_cats = array( get_option( 'default_category' ) );
        }
        $current_cats = array_values( $current_cats );
        wp_update_post( array(
            'ID'            => $post->ID,
            'post_category' => $current_cats,
        ) );
        echo "- Parsed " . $post->ID . "\n";
    }
}

if ($i === count($posts)) {
    wp_delete_term($old_tag, "post_tag");
    echo "Removed tag\n";
}
echo sprintf( _n( 'Moved %d post from the selected tag to the new category.', 'Moved %d posts from the selected tag to the new category.' , count( $posts ), 'bulk-move' ), count( $posts ) ) . "\n";

bulk-move.sh

#!/bin/bash

ids=(26310 45654 44303 44081)

for id in "${ids[@]}"; do
    echo "Processing ID: $id"
    ./wp eval-file ./bulk-move.php --skip-plugins --skip-themes "$id" 46900
done

wp-snippet.php

// Adds on the backend a column with all the term ids in category and tags
add_filter('manage_edit-category_columns', 'add_term_id_column');
add_filter('manage_edit-post_tag_columns', 'add_term_id_column');

function add_term_id_column($columns) {
    // Insert the ID column after the first column (usually the checkbox or name)
    $columns = array_slice($columns, 0, 1, true) +
    array('term_id' => 'ID') +
    array_slice($columns, 1, count($columns) - 1, true);
    return $columns;
}

add_action('manage_category_custom_column', 'populate_term_id_column', 10, 3);
add_action('manage_post_tag_custom_column', 'populate_term_id_column', 10, 3);

function populate_term_id_column($out, $column_name, $term_id) {
    if ($column_name == 'term_id') {
        $out = $term_id;
    }
    return $out;
}