User-specified file sharing

[Stephen R. van den Berg]

Gary Mills writes:
>Does anyone know of a way that groups of users can share files among
>themselves without requiring action by the administrator?

Suppose users "george" and "henry" want to share the files "fa" and "fb",
consider the following setup:

~henry						drwxr-xr-x 1 henry
     |george					drwx------ 1 george
     |	   |fa					-rw-rw-rw- 2 henry
     |	   |fb					-rw-rw-rw- 2 henry
     |henry					drwx------ 1 henry
          |fa					-rw-rw-rw- 2 henry
	  |fb					-rw-rw-rw- 2 henry

Where fa and fb are physically linked (ln henry/fa george/fa).

The only restriction is, that files can not be arbitrarily created or
removed.  (Though a suitably secure suid henry and george program can take
care of that).
--
Sincerely,                 berg at marvin.e17.physik.tu-muenchen.de
           Stephen R. van den Berg.
"I code it in 5 min, optimize it in 90 min, because it's so well optimized:
it runs in only 5 min.  Actually, most of the time I optimize programs."