title: MongoDB: replSet can't get local.system.replset config from self or any seed "server is not running with --replSet"
body: <p>I try to setup a Replica Set on Ubuntu 14.04 x64.
  First error I run into when trying   </p>
  
  <pre><code>$ sudo mongod --port 27017 --replSet rs0:
  
  replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)
  </code></pre>
  
  <p>I read that <code>&gt; rs.initiate()</code> solves that issue, so I do  </p>
  
  <pre><code>$ sudo service mongod start
  $ mongo
  rs.initiate()
  </code></pre>
  
  <p>which throws:</p>
  
  <pre><code>{ "ok" : 0, "errmsg" : "server is not running with --replSet" }
  </code></pre>
  
  <p>So if I can't start mongod with <code>--replSet</code> how can I solve the error within <code>rs.initiate()</code> which I need to solve the first error?
  It's like a vicious circle!</p>