Make new user sub-folders inherit parent permissions

[Phill Whiteside]

Hi,

have a read of
http://manpages.ubuntu.com/manpages/oneiric/man8/usermod.8.html

(usemod is pretty unchanged ever, as it is a 'core' Linux tool and applies
across all versions and flavours - Debian / Red Hat based).

I prefer to write down the user / group hierarchy on paper to envision how
the users apply to groups, you can either use the usermod function (always
use the *-aG* and not just -*G* or -*g* for 'adding' [appending] a user to
groups).

I also prefer to use the CLI usermod command, but you can do all these
tasks with the menu --> System Tools --> Users and Groups, which is the GUI
for usermod.

Regards,

Phill.

On 21 January 2013 02:50, Ioannis Vranos <ioannis.vranos at gmail.com> wrote:

> On Mon, Jan 21, 2013 at 2:40 AM, John Hupp <lubuntu at prpcompany.com> wrote:
> >
> > OK, thanks to all who have responded so far.
> >
> > From the several responses here and additional reading, I'm glad to come
> to
> > the understanding that there is only one set of user/group configuration
> > information (/etc/passwd, /etc/group and /etc/shadow), though it can be
> > managed by different available tools.  (This in contrast to network
> > configuration, which really does support two different configuration
> > systems.)
> >
> > For a case where it is desirable for a couple users to work with the same
> > set of files, I'm now thinking that my fundamental approach was not quite
> > right and that I do not need to involve or maybe should not involve the
> > "users" system group.
> >
> > What I'm now thinking should be the setup:
> > 1) Assign /home/user1 as the co-home directory for user2.
> > 2) Assign user2 to the user1 group as user2's *primary* group.
> > 3) Leave the ownership of /home/user1 as Owner: user1 and Group: user1.
> > With the /home/user1 permissions such that owner and group can edit,
> user1
> > and user2 should then be able to freely create, access and edit
> everything
> > in /home/user1.
> > 4) Delete /home/user2.
> >
> > I expect then that this would solve my original problem in which new
> > sub-folders did not inherit ownership by the "users" group.  And maybe
> > better respects Linux design principles.
> >
> > Is that a good and workable proposed setup?  Is there any obvious
> > consideration I am missing?
>
>
> Linux ownership also includes SetUID, and SetGID.
>
> If SetUID is set for an executable, then when any user runs this file,
> it is as if the user set by SetUID is running the file.
>
> If SetGID is set for an executable, it is as if the user that runs it,
> belongs to the group specified by SetGID.
>
>
> If SetGID is set for a directory, then all files created in this
> directory, by any user, have their group ownership set to the group
> specified by SetGID, and not to the primary group of the user that
> creates the file.
>
> So, I think in your situation, a nice approach is to add user1 and
> user2 to group "users" (NOT as their primary group), and then set the
> SetGID attribute of their common directory to "users".
>
>
> --
> Ioannis Vranos
>
> http://cppsoftware.binhoster.com
>
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