@echo off
Setlocal Enabledelayedexpansion
set str=^<a^>&set dos=&set fn=9.txt
for /f "tokens=*" %%i in ('findstr /n "$" %fn%') do (
set aa=%%i&set aa=!aa:*:=!
if not defined dos (
set dos=cndos
if defined aa (echo !str!!aa!>%fn%) else echo.>%fn%
) else if defined aa (echo !str!!aa!>>%fn%) else echo.>>%fn%
)