ls is a standard on many different shells, with different implementations.

Are there shells where `ls` is a built-in?

I just replied to another comment where I wanted to say that I don't mind that the PowerShell version is different because `ls` is a built-in. But then I discovered it's not. So I just used `cd` in that comment...

Read about the C shell's "ls-F" built-in command.

Don't get me started on the awfulness of csh...