Writing BAT file

Wikipedia Batch file
a batch file is a text file containing a series of commands intended to be executed by the command interpreter.

TECH-RECIPES Using variables in Windows batch files

@echo off
set var=testing 1 2 3
echo The variable is "%var%"

Computing.net DOS variables

@Echo Off
SetLocal EnableDelayedExpansion

Set var1=hello
Set var2=you
Set var3=...
set max=3
For /L %%i in (1,1,%max%) Do Echo !var%%i!

EndLocal

蘇言霖 MS-DOS的程式語言-Batch 進階篇3-3

史萊姆的家 Easy DOS command