[Foreigner]

Код:

@echo off

for /f "tokens=1,2" %%i in (' dir /b "file data.*" ') do ren "%%i %%j" "%%i%%j"

Код:

@echo off
setlocal

for /f "tokens=*" %%i in (' dir /b ') do call:ren "%%i"
goto:eof

:ren
set "file=%~1"
ren %1 %file: =%