How does the $_SERVER['REMOTE_USER'] variable work in PHP when multiple users log in through htaccess?

When multiple users log in through htaccess, the $_SERVER['REMOTE_USER'] variable in PHP will only contain the username of the user who authenticated last. This can be an issue if you need to identify all users who have logged in. One way to solve this is to store the usernames in a session variable when users log in and retrieve them from there when needed. 

session_start();

if (isset($_SERVER['REMOTE_USER'])) {
    $_SESSION['logged_in_users'][] = $_SERVER['REMOTE_USER'];
}

// To retrieve all logged in users
if (isset($_SESSION['logged_in_users'])) {
    foreach ($_SESSION['logged_in_users'] as $user) {
        echo $user . "<br>";
    }
}

Keywords

$_SERVER REMOTE_USER PHP htaccess multiple users

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