title: productsign error: SignData failed: CSSMERR_CSP_NO_USER_INTERACTION
body: <p>When signing an app from an ssh terminal session,  I am getting the following error:</p>
  
  <pre><code>productsign[29321:707] SignData failed: CSSMERR_CSP_NO_USER_INTERACTION (-2147415840)
  </code></pre>
  
  <p><em>productsign</em> was working until recently.</p>
  
  <p>How do I get around this error?</p>