Question about nethack and setgid

[Brandon Gooch]

On Wed, Mar 2, 2011 at 4:51 PM, David Demelier <demelier.david at gmail.com> wrote:
> Hello,
>
> I don't understand how nethack can store the score in
> /usr/local/lib/nethack/logfile.
>
> the real binary is here /usr/local/lib/nethack/nethack
>
> And the mode is
>
> -rwxr-sr-x  1 games  games  1793635 25 Jan 2011
> /usr/local/lib/nethack/nethack
>
> So that means people in games group will run nethack as games user (owner of
> file) but I'm not in games group ! and I can save the file located in
>
> /usr/local/lib/nethack/logfile which mode is -rw-rw-r--  games  games
>
> I'm writing a game that will store file too, because I can't make it works
> like nethack I was planning using the setuid mode but I don't like much this
> ..
>
> What am I misunderstanding?
>
> Cheers,
>
> --
> David Demelier

Take a look at:

http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/permissions.html#AEN4027

I believe that it will demystify the behavior you're seeing.

-Brandon