That is a posixly correct method to do arithmetic expressions.

i forget on the same day; i literally keep a log of everything i did that day so i can look it up. lol

Okay XD it's less funny when you have to explain the joke XD sorry !!

That twist at the end. Bloody hell.

Yeah, that's kind of my least favorite part about the existence of LLMs. Before, when someone wrote some code, there was a non-zero chance that they understood what they were doing and that the code is at least sane on a basic level. If they did some complex shit or even just wrote rather verbose code, you could be reasonably certain that they tried something simpler first.

Now, all of those assumptions are out the window. The biggest dumbass can generate code that looks alright at first glance and if you have to review it, you really don't know how to interpret it or how much to explain when you find fairly obvious mistakes.

Thats sounds a lot like C, in bash you cans also do for item in list; do echo $item; done

Arguably, I never fully learned Bash syntax, but it also is just a stupid if-statement. There shouldn’t be that much complexity in it.

There isn't. The syntax is

if COMMANDthenCOMMAND(s)...elseCOMMAND(s)...fi

I believe, if you write the then onto the next line, then you don’t need the semicolon.

Yes, but that's true of all commands.

foo; bar; baz

is the same as

foobarbaz

All the ] and -z stuff has nothing to do with if. In your example, the command you're running is literally called [. You're passing it three arguments: -z, "$var", and ]. The ] argument is technically pointless but included for aesthetic reasons to match the opening ] (if you wanted to, you could also write test -z "$var" because [ is just another name for the test command).

Since you can logically negate the exit status of every command (technically, every pipeline) by prefixing a !, you could also write this as:

if ! test "$var"; then ...

The default mode of test (if given one argument) is to check whether it is non-empty.

Now, if you don't want to deal with the vagaries of the test command and do a "native" string check, that would be:

case "$var" in  "") echo "empty";;  *) echo "not empty";;esac

Why -z? I have no idea.

From man test (note that [ <expr> ] is just sugar for test <expr>):

       -n STRING
              the length of STRING is nonzero

       -z STRING
              the length of STRING is zero

So, -z stands for Zero.

Hope this helps you remember it!

You could write that as 1 line:

[ -z "$var" ] && echo "empty" || echo "no it aint"

-z means zero length and mostly [[ ]] are used when you want to add multiple conditions. But there are also few test cases which are only in bash so they also need double brackets

OH!