title: How to programmatically really clean Delete files?
body: <p>So you are about to pass your work-computer to some of your colleague. How do you make sure you really delete all your personal data?</p>
  
  <p>Re-formatting, Re-installing OS will not really solve the problem. </p>
  
  <p>I searched around and <a href="http://www.killdisk.com/wiping.htm" rel="noreferrer">found</a> <a href="http://www.guidancesoftware.com/products/ef_index.asp" rel="noreferrer">some</a> <a href="http://hddguru.com/content/en/software/2006.04.13-HDD-Wipe-Tool/" rel="noreferrer">programs</a> does "Wipe out" disks.</p>
  
  <p>This caught me thinking how does those programs work?
  I mean, What algorithms they use and how low level those implementations go?</p>
  
  <p>Any ideas?</p>