One big difference with POSIX/UNIX is the lack of multiple users. My understanding is Haiku is working to add support for multi-user/privilege separation of some kind, but at least for BeOS this was a fairly big difference.
Haiku already has support for multiple users at the kernel and filesystem level. You can `useradd`, `passwd`, and then `su` (or even SSH into your newly-created user on your Haiku install from another machine), and also `chown`, `chmod`, etc.
What isn't properly supported yet is running GUI applications as anything other than UID 0. Adding support for that will require some careful refactoring across a few different components. Actually, if you added a handful of hacks in a few places it might work already...
What isn't properly supported yet is running GUI applications as anything other than UID 0. Adding support for that will require some careful refactoring across a few different components. Actually, if you added a handful of hacks in a few places it might work already...