Coming Soon Snippet

// add a page called Coming Soon and adjust it to your needs
// your url should look like this: domain.com/coming-soon/
// then simply paste this into you themes functions.php

add_action( 'init', function()
{

    if( ! is_user_logged_in() )
    {

        if ( isset( $_SERVER['REQUEST_URI'] )
            && ( '/coming-soon/' == $_SERVER['REQUEST_URI']
                || '/wp-admin/' == $_SERVER['REQUEST_URI']
                || false !== strpos( $_SERVER['REQUEST_URI'], 'wp-login.php' ) ) ) return;

        wp_redirect( '/coming-soon/' );

        exit;

    }

});