how to share a directory tree with files in it with multiple users (Re: [gentoo-user] local shared directory)

[hw]

hw schrieb:
> Neil Bothwick schrieb:
>> On Thu, 17 Mar 2016 18:38:56 -0400, Rich Freeman wrote:
>>
>>>> umask is just not viable either, as a) it's global and affects all
>>>> files a user creates and b) by definition umask is modifiable by the
>>>> user (it's a feature to help users out so they don't need to chmod
>>>> every file every time) and c) you can't stop them doing it (by
>>>> design).
>>>
>>> Actually, this is completely viable.  Just set the default umasks to
>>> 007, and create a new group for each user as their default group (and
>>> don't have all their home directories be owned by some users group).
>>> This is how this sort of situation was handled long before POSIX ACLs
>>> became common, and I know that some distros behave this way by default
>>> for this reason (this was the case in the distro I used right before I
>>> switched to Gentoo).
>>>
>>> If users chmod a file then tell them not to.  If you must, set up some
>>> cron job to clean up after them.
>>>
>>> But, you can of course do this with ACLs as well.  I haven't tried
>>> setting those up personally.
>>
>> I've done this with ACLs in the past, which is why I suggested it, but
>> it's a pain to set up if you haven't used them before. Alan's suggestion
>> of using inotify is probably simplest. Install incrond and put something
>> like this in a file in /etc/incron.d
>>
>> /shared/dir IN_CREATE,IN_MODIFY chmod g+w $#
>>
>>
>
> PS: How about subdirectories?  The users sharing the directory can
> create and delete them as well, and files within them; yet incron
> ignores what happens in subdirectories.
>
> Using 'chmod -R g+w $#' isn't very appealing, and how safely does it
> handle file names?
>
>


PPS: Since it is impossible to share a local directory tree with 
multiple users, I'm trying to use a directory tree on a server, which is 
exported using samba and mounted by an entry in fstab.  (I could also 
use nfs, if it helps.)

That still doesn't work.  How do I calculate an appropriate 'create 
mask' for the smb.conf to at least force the files group writable?  I 
wouldn't even mind if all the files belonged to the same user.  Or what 
would I need to do?

Has it become entirely impossible to share a directory tree and the 
files in it with multiple users when Linux is involved?  This should be 
a very simple thing to accomplish.