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From: arnold@skeeve.com
To: dot@dotat.at, arnold@skeeve.com
Cc: tuhs@tuhs.org, doug@cs.dartmouth.edu
Subject: Re: [TUHS] Additional groups and additional directory permissions
Date: Sun, 04 Aug 2019 00:40:47 -0600	[thread overview]
Message-ID: <201908040640.x746elpl029042@freefriends.org> (raw)
In-Reply-To: <alpine.DEB.2.20.1908021139530.11612@grey.csi.cam.ac.uk>

> arnold@skeeve.com <arnold@skeeve.com> wrote:
> > Arthur Krewat <krewat@kilonet.net>:
> > > There's also the setgid bit on directories, that when files are created,
> > > they will be in the group that the parent directory has on it.
> >
> > IIRC this was a Sun invention. It was in SunOS 4.x, and may even have
> > been in SunOS 3.x.

Tony Finch <dot@dotat.at> wrote:
> When Bill Joy added the "multi-group stuff" to BSD all directories became
> implicitly set-gid:

Yes.  But the commercial world had backwards compatibility to worry about.
Thus the setgid bit on directories. I'm no longer sure who first came
up with it.

> As I understand it, when group support was improved in System V they did
> not change creat() to match BSD but instead used the directory set-gid bit
> to provide opt-in BSD semantics. I don't know if this was in Solaris or
> earlier?

Correct, but not sure when it was first done.

> > > Also, I don't think it's been mentioned, but there's the setuid bit on
> > > directories - otherwise known as the sticky bit. When set, even if you
> > > have rights to "write" the directory (meaning, delete files), you can't
> > > delete those owned by other users. Useful for /tmp
> >
> > Also a SunOS invention, IIRC.
>
> BSD again :-) SCCS revision 6.6 so I think it appeared in 4.3BSD

That sounds right. I stand corrected.

Thanks,

Arnold

  reply	other threads:[~2019-08-04  6:41 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-01 12:35 [TUHS] Who's behind the UNIX filesystem permission Doug McIlroy
2019-08-01 16:22 ` John P. Linderman
2019-08-01 16:35   ` Arthur Krewat
2019-08-02  8:35   ` [TUHS] Additional groups and additional directory permissions arnold
2019-08-02 11:18     ` Tony Finch
2019-08-04  6:40       ` arnold [this message]
2019-08-02 12:45     ` Arthur Krewat
2019-08-02 13:06     ` Clem Cole
2019-08-02 13:28     ` Clem Cole
2019-08-02 19:00       ` Thomas Paulsen
2019-08-01 17:01 ` [TUHS] Who's behind the UNIX filesystem permission Nemo Nusquam
2019-08-01 18:26   ` Arthur Krewat
2019-08-01 20:14     ` Lyndon Nerenberg
2019-08-01 21:23 ` Dave Horsfall
2019-08-02 19:44 [TUHS] Additional groups and additional directory permissions Norman Wilson
2019-08-10  4:02 Kirk McKusick
2019-08-10  6:02 ` Thomas Paulsen

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