title: Windows batch script: substring calculation
body: <p>I have a situation like this. I have a list of urls in a file.</p>
  
  <p><code>SET str1="http://www.domain.com/dir1/dir2/dir3/dir4/dir5/file1.txt"</code></p>
  
  <p>In the above string <code>http://www.domain.com/dir1/dir2/dir3</code> is constant in all the urls. 
  I need to extract the rest of the path in each url.</p>
  
  <p>I mean, i need to get the final string from the above url is <code>/dir4/dir5/file1.txt</code></p>
  
  <p>Thanks</p>