[Georgio]

Код:

@echo off
setlocal enabledelayedexpansion
for %%i in (
 Jan Feb Mar Apr May Jun
 Jul Aug Sep Oct Nov Dec
) do (
 set /a n+=1
 set month=0!n!
 set month=!month:~-2!
 set !month!=%%i
)
(
for /f "usebackq tokens=1-5 delims=-, " %%i in (
 "log.txt"
) do (
 echo %%m - - [%%k/!%%j!/%%i:%%l +0400] "ip"
)>"log_new.txt"
endlocal
exit /b