This usually messes stuff up pretty good:<p><pre><code>  perl -e &#x27;$file = &#x27;&#x2F;dev&#x2F;sda&#x27;;\
  $s = -s $file;\
  $i = $s&#x2F;2;\
  while(--$i &gt; 0){\
    $r = int rand($s);\
    system(&quot;dd if=&#x2F;dev&#x2F;urandom of=$file skip=$r count=1&quot;);\
  }&#x27;</code></pre>