Discussion
Various LLMs tell me that Mac OS X used to use User Private Groups https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/5/html/deployment_guide/s1-users-groups-private-groups
While this does ring a bell for me, I can't find any links to confirm it (nor can the LLMs when I ask for a source link for this info). Does any human out there have a source link? (Information source or source code, I guess.)
Unix for Mac OS X 10.4 Tiger: Visual QuickPro Guide (2nd Edition) by Matisse Enzer confirms it in the "About Users and Groups" chapter:
"In some Unix systems (including Mac OS X 10.4 Tiger) a new group is normally created when you create a new user account. The new group has the same name as the user's user name, and the gid number is the same as the new uid number. The new user will be the only member of this user private group."
@siracusa well now I’m going to fall down the rabbit hole of how the hell did I miss that?!
@siracusa I feel like that’s half true. I think the gid and uid are the next available. If you first create a group and then create a user (which creates a group), the gid would be one higher.
Also confirmed using Tiger on infinitemac.org:
@siracusa man, these modals were so great...
@siracusa Interesting, I don't know if I have ever created a non-admin user on MacOS does tiger have the same behavior for a admin user? It begs the question why did Apple stop using private groups.
@glennbrown I don't know what it does for a non-admin user, but I suspect it's the same. (The emulator was really slow, so it was quite a slog to test this. Feel free to try it on you own.)
@siracusa I still have a Mac running Tiger…
@siracusa I've got 10.2 emulating in UTM and umask does show 022. Just based on my limited understanding that seems to indicated that it did support UPGs.
@siracusa Mac OS X has never had this. I don’t know about developer previews or next step or whatever. Source: I’ve done Unix development and porting on my Mac since 10.0. I don’t have a link because it’s hard to prove a negative.
@siracusa if you wanted to, one thing you could try is running Mac OS X versions on https://infinitemac.org and taking a look, but it doesn’t have all versions available
@siracusa unfortunately I think the person to ask is John Siracusa.
@siracusa i noticed that when i first started using macos x in the early aughts. ( A group name the same as a username ) . I’ve never seen it documented or a reason for it .
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@siracusa pretty sure the llm is wrong in this case, macOS as long as I have used it defaults to using the group staff for users. Most major Linux distributions have defaulted to private groups matching the username for many years now for local accounts.