Login/Logout Shortcode

login-out.php

<?php //<~ remove if using in functions.php

add_shortcode( 'login_logout', 'login_logout' );
/**
 * Add a login/logout shortcode button
 * @since 1.0.0
 */
function login_logout() {
ob_start();
    if (is_user_logged_in()) : 
    // Set the logout URL - below it is set to the root URL
    ?>
    <a role="button" href="<?php echo wp_logout_url('/'); ?>">Log Out</a>

<?php 
    else : 
    // Set the login URL - below it is set to get_permalink() - you can set that to whatever URL eg '/whatever'
?>
    <a role="button" href="<?php echo wp_login_url(get_permalink()); ?>">Log In</span></a>

<?php 
    endif;

return ob_get_clean();
}