title: Rename multiple files, but only rename part of the filename in Bash
body: <p>I know how I can rename files and such, but I'm having trouble with this.</p>
  
  <p>I only need to rename <code>test-this</code> in a for loop.</p>
  
  <pre><code>test-this.ext
  test-this.volume001+02.ext
  test-this.volume002+04.ext 
  test-this.volume003+08.ext 
  test-this.volume004+16.ext 
  test-this.volume005+32.ext 
  test-this.volume006+64.ext 
  test-this.volume007+78.ext 
  </code></pre>