:BEGIN
  @echo off
  @echo Save old log file
  if exist <FILENAME> GOTO SAVE
  echo "No file to save"
:START
  echo Start logging...
  start putty.exe -load "SESSIONNAME"
  GOTO END
:SAVE
  setlocal
  set /a cnt = 0
:LOOP:
  set /a cnt += 1
  if exist <FILENAME>%cnt% GOTO LOOP
  copy <FILENAME> <FILENAME>%cnt%
  del <FILENAME>
  echo Last file saved as <FILENAME>%cnt%
  GOTO START
:END
  @echo on
  @exit 0