tireless

@echo off
set file="1.txt"
set "old=FFFFFFFFFF"
set "new=别的字符"
 
(for /f "delims=" %%a in ('findstr /n .* %file%') do (
  set var=%%a
  setlocal enabledelayedexpansion
  if "!var:%old%=!" neq "!var!" (
    set var=!var:*:=!
    echo;!var:%old%=%new%!
  ) else echo;!var:*:=!
  endlocal
))>.new
 
copy %file% %file%.backup>nul
move .new %file%
start "" %file%COPY