code: private void handleBackKey() throws IOException {
  		if (commandLineBuffer.size() > 0 && curPos > 0) {
  			if (echoEnabled) {
  				ps.write(BACK);
  			}
  			String curLine = overwriteCommandlineSkippingChar(curPos - 1);
  			eraseLastCharAndMoveBack(curLine, curPos);
  			curPos--;
  		}
  	}
docs: Rewrites the command line to show changes as a result of hitting the back key
  even if the cursor is positioned in the middle of the command line
  
  @throws IOException