title: How to modify the filename in shell script?
body: <p>I have 3 text files.I want to modify the file name of those files using for loop  as below .</p>
  
  <p>Please find the files which I have </p>
  
  <p>1234.xml</p>
  
  <p>333.xml</p>
  
  <p>cccc.xml</p>
  
  <p>Output:</p>
  
  <p>1234_R.xml</p>
  
  <p>333_R.xml</p>
  
  <p>cccc_R.xml</p>