[alpap]

Код:

@echo off
set "d=C:\papka"
set "f=file.txt"

<"%f%" set /p z=
for /f "tokens=1* delims=[]" %%a in ('dir /a-d/b "%d%\*.jpg"^|find /n /v ""') do ren "%d%\%%b" "%z%_%%a%%~xb"
pause