title: Updating File Created Date by x number of days Mac OSX
body: <p>I have a folder of videos (Mac OSX Yosemite) for which I need to change the Created Date by adding 2180 days to the existing Created Date.</p>
  
  <p>Using SetFile from Terminal I am able to manipulate the Created Date, for example I can set it as equivalent to the Modified Date of the same file:</p>
  
  <pre><code>SetFile -d "$(GetFileInfo -m /Users/myfilename.mov)" /Users/myfilename.mov
  </code></pre>
  
  <p>However, if I try to add the ‘Add 2180 days’ part it stops working:</p>
  
  <pre><code>SetFile -d "$(GetFileInfo -d /Users/myfilename.mov) +2180 days" /Users/myfilename.mov
  </code></pre>
  
  <p>I suspect it is an issue with bracket and speech marks but the following did not work either:</p>
  
  <pre><code>SetFile -d "$(GetFileInfo -d /Users/myfilename.mov +2180 days)" /Users/myfilename.mov
  </code></pre>
  
  <p>How exactly should I be incorporating the '+2180 days' into it?</p>
  
  <p>Edi: Mark Setchell has a solution which works but I am keen to know if there is in fact a way to incorporate '+2180 days' into the GetFileInfo-based -d date variable.</p>