damn is this tmpfs thing on #macOS stupid.

turns out:
> sudo mount -t tmpfs -- -i ~/tmp

as well as
> sudo mount -t tmpfs -- -- ~/tmp

WORK. They currently pass the arguments along as is to the mount_tmpfs command and that one doesn't like the string "tmpfs" as its first argument.

And apple for whatever reason assumed that this would work (maybe it did in the past, don't know):
> sudo mount -t tmpfs ~/tmp

but it doesn't as mount doesn't allow that syntax.

#tmpfs #mount