setlocal enabledelayedexpansion
set str=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz
set n=%time::=%
set n=%n:.=%
set /a v1=%n%%%52
set /a n/=52
set /a v2=%n%%%52
set /a n/=52
set /a v3=%n%%%52
echo.&echo !str:~%v1%,1!!str:~%v2%,1!!str:~%v3%,1!
@echo off
setlocal enabledelayedexpansion
set "str=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
set /a v1=%random%%%52
set /a v2=%random%%%52
set /a v3=%random%%%52
echo.&echo !str:~%v1%,1!!str:~%v2%,1!!str:~%v3%,1!
pause >nul
@echo off
setlocal enabledelayedexpansion
set z=ABCDEFGHIJKLMNOPabcdefqrstuvwxyz
for /l %%1 in (1,1,300) do (set c=&for /l %%2 in (1,1,3) do set /a a=!random!%%32&for %%# in (!a!) do set c=!c!!z:~%%#,1!)&echo !c!
pause