Show Post/Page IDs in backend

functions.php

add_filter('manage_posts_columns', 'posts_columns_id', 5);
add_action('manage_posts_custom_column', 'posts_custom_id_columns', 5, 2);
add_filter('manage_pages_columns', 'posts_columns_id', 5);
add_action('manage_pages_custom_column', 'posts_custom_id_columns', 5, 2);
 
function posts_columns_id($defaults){
    $defaults['wps_post_id'] = __('ID');
    return $defaults;
}
 
function posts_custom_id_columns($column_name, $id){
    if($column_name === 'wps_post_id'){
        echo $id;
    }
}