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user private groups and a src group

   Date: Mon, 07 Mar 1994 13:45:59 +1000
   From: Matthew Hannigan <matth@ucc.su.OZ.AU>

   birkholz@midnight.com (Matt Birkholz) writes in part:
   > Linux still implements the SYSV method for assigning group
   > membership to new files.  (It assigns the default group of the process
   > creating the file.)

   Linux will (at least for ext2, I presume it is fs independent) use BSD
   semantics for the group of new files if you set the gid of the
   directory.  This gid bit is also inherited by new sub-directories.
   This makes the scheme quite workable.

Thank you.  That's the bit I was missing.

   I pointed this out (obliquely) in my message which started this thread.

I'm glad you did.

   But I don't particularly care if debian takes this route although I
   think it brings big benefits if you're cooperating in groups.
   And very little cost (a bigger group file).

It's nice not to have to maintain lots of diffs between the distribution
and the setup you actually use.  Thus, I care, at least a little bit.  The
need for root to maintain groups doesn't seem to be an obstacle.  Group
membership is changed only infrequently and there is always sudo.

   Date: Mon, 7 Mar 94 04:33 PST
   From: "Remy Card" <card@masi.ibp.fr>

	   Hmm, this is SVR4 semantics.  Every file system in Linux honors
   the setgid bit on directories.  When a directory has the setgid bit set,
   new files and subdirectories inherit the directory's group.

That's good to know.

	   Note that ext2fs also has support for true BSD semantics.  If you
   mount a file system with the `bsdgroups' option (or the `grpid' option which
   is a synonym added for SunOS compatibility), new files and subdirectories
   inherit the group id of the parent directory regardless of the setgid
   bit.  The default behavior is SVR4 semantics (`sysvgroups' or `nogrpid'
   option) but you can change it at mount time.

That beats munging all my directories to get the same effect.  Thanks!

Matthew Birkholz

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