title: How to change default shell in a GCE VM instance?
body: <p>I've successfully created and logged into a GCE VM with <code>ssh -i ~/.ssh/google_compute_engine &lt;EXTERNAL IP&gt;</code>. </p>
  
  <p>The VM is running ubuntu 18.04 LTS. I've installed zsh. I've verified that the output of <code>which zsh</code> appears in <code>/etc/shells</code>. </p>
  
  <p>When I try to run <code>chsh -s $(which zsh)</code> I'm prompted for a password and I have no idea what to enter. </p>
  
  <p>When I created <code>~/.ssh/google_compute_engine</code> (which was created during a <code>gcloud ssh</code> command issued earlier) I didn't enter a passphrase for the ssh key. </p>
  
  <p>How can I change my shell?</p>
  
  <p>EDIT: Here's what I see when I've logged in:</p>
  
  <pre>
  paymahn@paymahn:~$ chsh -s $(which zsh)
  Password:
  chsh: PAM: Authentication failure
  </pre>