Wordpress Change Default Display Name Publicy As for all existing users

Question

does anyone know of way I can change the existing display name publicly as for all users. I want to have firstname lastname as the default because this will reflect in the forum

Answer 1

Quick and dirty hack would be to edit the file 'wp-includes/user.php' edit the folowing

if ( empty($display_name) )
    $display_name = $user_login;
    $display_name = apply_filters('pre_user_display_name', $display_name);

Edit this line

$display_name = $user_login;

Change to:

$display_name = $first_name . ' ' . $last_name;

The above solution should work, assuming that the user.php file isn't changed in a WordPress update or alternativly you could add something like this to your functions.php

//force display-name of users to Firstname Lastname
add_action('admin_head','force_pretty_displaynames');
function force_pretty_displaynames() {
    $current_user = wp_get_current_user();
    if ($current_user->display_name != $current_user->first_name." ".$current_user->last_name){ 
       update_user_meta($current_user->ID, 'display_name', $current_user->first_name." ".$current_user->last_name);
    }

}

but agian a few checks on this above could be added to see if the user is logged in, is an admin, contributor etc..etc..

but should do what your looking for..

Source: http://wordpress.org/support/topic/change-default-display-name-1

Marty