[jagger27]

It’s a shell built-in.

[pxc]

No, macOS has an executable called `command` so that it is available even on shells that don't implement the builtin

[jagger27]

If you look at the last part of my comment, you’ll see it’s just a shell script that invokes the built-in.

[pxc]

Yeah, I discovered that after I made my previous comment, and before I saw your whole long one.

It's a weird choice, because it means that command will sometimes tell you about 'builtins' that are not actually built in to the shell you invoke it from, including `command` itself.