Intermediate

You can write basic scripts but you keep hitting bugs that make no sense — a variable that won't update inside a loop, a comparison that's always false, a script that "works" but leaves junk in your environment. This level explains why, and gives you the patterns that make batch scripts reliable.

Lessons

#	Lesson	You'll learn
1	Delayed expansion	setlocal enabledelayedexpansion, !var!, the loop-variable bug
2	String manipulation	substrings %v:~n,m%, substitution %v:a=b%, length, case
3	for /F deep dive	tokens, delims, skip, eol, usebackq; parsing command output
4	Error handling & exit codes	errorlevel vs %errorlevel%, &&, ||, exit /b n
5	setlocal, endlocal & scope	environment isolation, returning a value past endlocal
6	Arrays & pseudo data structures	set "a[0]=...", counts, iteration, associative lookups
7	Date, time & math	%date%/%time% locale traps, set /a operators & bases
8	User interaction & menus	choice, set /p, a robust menu loop
9	Scheduling & running scripts	schtasks, start, elevation, runas, working directory
10	Capstone: backup utility	logging, rotation, error handling, exit codes

How to work through it

• Every lesson here fixes a bug you have already hit or are about to. Type the "broken" examples too — seeing the failure is the point.
• Keep Lesson 1 (delayed expansion) close; it explains half of all batch weirdness.

When you're done

Go to Advanced.