title: How to rename a file by retaining first 6 characters of my file name and remove rest of the characters?
body: <p>I have file names like: Rv0012_gyrB.txt, Rv0001_Rv.txt
  How to rename a file by retaining first 6 characters of my file name and remove rest of the characters?
  My desired output should be:
  Rv0012.txt and Rv0001.txt
  Please let me know, how to do it using a script in Linux for multiple files.</p>