title: Match line not containing a pattern in BBEdit with Grep
body: <p>I am having trouble finding the correct grep expression for not matching entire lines in BBEdit that do not contain a date, despite having found many "match ... not containing" topics on this on the web...</p>
  
  <p>I have this text document:</p>
  
  <pre><code>Some Text
  Some more text,even more text,2015-06-17,2015-06-20
  A third line of text
  Last line of text, 2015-06-17
  </code></pre>
  
  <p>This expression will select all lines that contain a date reference, in the form of 4 digits + "-" + 2 digits + "-" + 2 digits</p>
  
  <pre><code>^.*\d\d\d\d-\d\d-\d\d.*$
  </code></pre>
  
  <p>I would like to match exactly the opposite, with the intention to remove all lines that do not contain a date reference. I have tried solutions like</p>
  
  <pre><code>^.*[^\d\d\d\d-\d\d-\d\d].*$
  </code></pre>
  
  <p>but with no success so far. Can someone point me in the right direction?
  Thank you.</p>