title: How to Get a Substring Using Positive and Negative Indexes in Bash
body: <p>What I want is pretty simple. Given a string 'this is my test string,' I want to return the substring from the 2nd position to the 2nd to last position. Something like: 
  <code>substring 'this is my test string' 1,-1</code>. I know I can get stuff from the beginning of the string using cut, but I'm not sure how I can calculate easily from the end of the string. Help?</p>