How to redirect after login in PHP

Question

I have a simple website trying to figure out how to redirect to home.php after login at the moment it just stays in the login page.

    <?php
  session_start();



  if (!isset($_SESSION['username'])) {
    $_SESSION['msg'] = "You must log in first";
    header('location: login.php');
  }
  if (isset($_GET['logout'])) {
    session_destroy();
    unset($_SESSION['username']);
    header("location: login.php");
  }
?>

Answer 1

Add to login.php:

if (isset($_SESSION['username'])) {
header("Location: /home.php");
}