[Georgio]

Код:

@echo off

pushd "logs\old"
(
for /f "usebackq delims=" %%i in ("..\new.log") do (
 for %%j in (
  "old1.log"
  "old2.log"
  "old3.log"
  ) do (
  for /f "usebackq delims=" %%k in (%%j) do (
   set /p=%%k<nul| findstr /lc:"%%i">nul&& (
   set /a count+=1
   for /f %%l in ('
    set /a count
   ') do (
    if %%l==5 (
     echo.%%i
     )
    )
    )
   )
  )
 set count=
 )
)>"%~dp0result.log"
popd

exit /b