То же, но без If
Код:

@Echo Off
cls
Set "Prg="Program.exe" /F"
Set "Mask=log*."
Set "BoxIn=C:\11"
FOR /F "usebackq delims=" %%f IN (`2^>nul Dir "%BoxIn%\%Mask%" /B /A:-D /O:-D /T:C`) DO (
Start " " %Prg% "%BoxIn%\%%f"
Exit /B
)
Echo !!! Folder Or Files "%BoxIn%\%Mask%" not found
Exit /B 1