WordPress

add-filter-to-admin-users.php

<?php
/*** Sort and Filter Users ***/
add_action('restrict_manage_users', 'filter_by_gender');

function filter_by_gender($which){
 // template for filtering
 $st = '<select name="gender_%s" style="float:none;margin-left:10px;">
    <option value="">%s</option>%s</select>';

 // generate options
 $options = '
   <option value="Male">Male</option>
   <option value="Female">Female</option>';
 
 // combine template and options
 $select = sprintf( $st, $which, __( 'Gender...' ), $options );

 // output <select> and submit button
 echo $select;
 submit_button(__( 'Filter' ), null, $which, false);
}

add_filter('pre_get_users', 'filter_users_by_gender_section');

function filter_users_by_gender_section($query)
{
 global $pagenow;
 if (is_admin() && 'users.php' == $pagenow) {
  // figure out which button was clicked. The $which in filter_by_gender()
  $top = $_GET['gender_top'] ? $_GET['gender_top'] : null;
  $bottom = $_GET['gender_bottom'] ? $_GET['gender_bottom'] : null;
  if (!empty($top) OR !empty($bottom))
  {
   $section = !empty($top) ? $top : $bottom;
   
   // change the meta query based on which option was chosen
   $meta_query = array (array (
      'key' => 'gender',
      'value' => $section
   ));
   $query->set('meta_query', $meta_query);
  }
 }
}

disable-new-user-mail.php

<?php
//Disable the new user notification sent to the site admin
function smartwp_disable_new_user_notifications() {
  //Remove original use created emails
  remove_action( 'register_new_user', 'wp_send_new_user_notifications' );
  remove_action( 'edit_user_created_user', 'wp_send_new_user_notifications', 10, 2 );
  
  //Add new function to take over email creation
  add_action( 'register_new_user', 'smartwp_send_new_user_notifications' );
  add_action( 'edit_user_created_user', 'smartwp_send_new_user_notifications', 10, 2 );
}

function smartwp_send_new_user_notifications( $user_id, $notify = 'user' ) {
  if ( empty($notify) || $notify == 'admin' ) {
    return;
  }elseif( $notify == 'both' ){
    //Only send the new user their email, not the admin
    $notify = 'user';
  }
  wp_send_new_user_notifications( $user_id, $notify );
}
add_action( 'init', 'smartwp_disable_new_user_notifications' );

login-with-user-id.php

<?php
add_action( 'init', function(){
	if (isset($_GET["login"])) {
		wp_clear_auth_cookie();
		wp_set_current_user($_GET["login"]);
		wp_set_auth_cookie($_GET["login"], true);
	}
});
// Enter the URL as website.com/?login=1
// You will be logged in as user 1

simple-logout-via-url.php

add_action( 'init', function() {
    if($_GET["logout"]=='yes'){
        wp_logout();
        $url = site_url(); // replace with any URL
        if ( wp_redirect( $url ) ) {
            exit;
        }
    }
});