title: Extract user email address in Laravel with Artisan::call
body: <p>I want to know how can I put $user->email in the following code snippet, where the email address is. Everything works well when hard coded in but not when I put $user->email where the email address is - I get error then. Please help. thanks.</p>
  
  <pre><code>        public function runCommand(Request $request){
            $user = User::all();
            $signature = $request-&gt;input('signature');
            $command =  Artisan::call($signature, ['user' =&gt; 'myemail@email.co.za']);
            return response($command);
  }
  </code></pre>