[gora]

Devils0411, попробуйте так:

Код:

@Echo Off
Setlocal EnableDelayedExpansion
For /F "Delims=" %%I In (a.txt) Do (
	Set Line=%%~dpI
	Echo !Line:~3,-1!>>temp.txt
)
Copy /y temp.txt a.txt
Del /q temp.txt
Pause