@echo off
Setlocal Enabledelayedexpansion
set "str=abcdefghijklmnopqrstuvwxyz1234567890+-_"
for /l %%a in (1 1 200) do (
set /a "m=!random!%%39"
call set "var1=%%var1%%%%str:~!m!,1%%"
)
set "var=%var1%"
for /l %%a in (1 1 20) do (
set "var2=!var:~,10!"
set /p =!var2! <NUL
set "var=!var:~10!"
)
echo.&echo.&set "var=%var1%"
for /l %%a in (1 1 20) do (
set "var2=!var:~,10!"
echo.!var2!
set "var=!var:~10!"
)
pause>nul