Re: The Free Unices (GPL restrictions)

[phr@netcom.com (Paul Rubin)]

The GPL requires that (1) you must ship source or make it available;
(2) anyone who receives the program from you can redistribute it
further under the GPL; (3) any modified versions that you distribute
of a GPL'd program must also be GPL'd.  The idea is to make sure that
not only is the original GPL'd program free, but everyone can get the
source so that they can modify and improve it, and the improved
versions are also free.  Although the Linux kernel is GPL'd BSD
4.4-lite kernel is not, all the complete programming environments
that I know of based on these kernels, including the commercial BSDI
system, depend heavily on GPL'd software such as the GNU C compiler.
So if you buy a BSDI system, its kernel is proprietary but you're
allowed to freely redistribute the C compiler that came with it.

For more info, see the GPL itself (distributed with Linux and with all
GNU programs such as GNU Emacs), or the article "What is Copyleft?"
in the Free Software Foundation newsletter "GNU's Bulletin",
or write fsf@gnu.ai.mit.edu.

The list has been very active lately--I hope we can keep further
traffic on this subject to a minimum.
Thanks