66
Preamble
The licenses for most software are designed to take away
your freedom to share and change it. By contrast, the
GNU General Public License is intended to guarantee your
freedom to share and change free software--to make sure
the software is free for all its users. This General Public
License applies to most of the Free Software Foundation’s
software and to any other program whose authors commit
to using it. (Some other Free Software Foundation software
is covered by the GNU Lesser General Public License
instead.) You can apply it to your programs, too.
When we speak of free software, we are referring to
freedom, not price. Our General Public Licenses are
designed to make sure that you have the freedom to
distribute copies of free software (and charge for this service
if you wish), that you receive source code or can get it if you
want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these
things.
To protect your rights, we need to make restrictions that
forbid anyone to deny you these rights or to ask you to
surrender the rights. These restrictions translate to certain
responsibilities for you if you distribute copies of the
software, or if you modify it.
For example, if you distribute copies of such a program,
whether gratis or for a fee, you must give the recipients all
the rights that you have. You must make sure that they, too,
receive or can get the source code. And you must show
them these terms so they know their rights.
We protect your rights with two steps: (1) copyright the
software, and (2) offer you this license which gives you legal
permission to copy, distribute and/or modify the software.
Also, for each author’s protection and ours, we want to
make certain that everyone understands that there is no
warranty for this free software. If the software is modi ed by
someone else and passed on, we want its recipients to know
that what they have is not the original, so that any problems
introduced by others will not re ect on the original authors’
reputations.
Finally, any free program is threatened constantly by
software patents. We wish to avoid the danger that
redistributors of a free program will individually obtain
patent licenses, in effect making the program proprietary. To
prevent this, we have made it clear that any patent must be
licensed for everyone’s free use or not licensed at all.
The precise terms and conditions for copying, distribution
and modi cation follow.
TERMS AND CONDITIONS FOR COPYING,
DISTRIBUTION AND MODIFICATION
This License applies to any program or other work which
0.
contains a notice placed by the copyright holder saying it
may be distributed under the terms of this General Public
License. The “Program”, below, refers to any such program
or work, and a “work based on the Program” means either
the Program or any derivative work under copyright law:
that is to say, a work containing the Program or a portion
of it, either verbatim or with modi cations and/or translated
into another language. (Hereinafter, translation is included
without limitation in the term “modi cation”.) Each licensee
is addressed as “you”.
Activities other than copying, distribution and
modi cation are not covered by this License; they are
outside its scope. The act of running the Program is not
restricted, and the output from the Program is covered
only if its contents constitute a work based on the
Program (independent of having been made by running
the Program). Whether that is true depends on what the
Program does.
You may copy and distribute verbatim copies of the
1.
Program’s source code as you receive it, in any medium,
provided that you conspicuously and appropriately
publish on each copy an appropriate copyright notice
and disclaimer of warranty; keep intact all the notices
that refer to this License and to the absence of any
warranty; and give any other recipients of the Program a
copy of this License along with the Program.
You may charge a fee for the physical act of transferring
a copy, and you may at your option offer warranty
protection in exchange for a fee.
You may modify your copy or copies of the Program
2.
or any portion of it, thus forming a work based on the
Program, and copy and distribute such modi cations or
work under the terms of Section 1 above, provided that
you also meet all of these conditions:
You must cause the modi ed les to carry prominent
a)
notices stating that you changed the les and the
date of any change.
You must cause any work that you distribute or
b)
publish, that in whole or in part contains or is derived
from the Program or any part thereof, to be licensed
as a whole at no charge to all third parties under the
terms of this License.
If the modi ed program normally reads commands
c)
interactively when run, you must cause it, when
started running for such interactive use in the most
ordinary way, to print or display an announcement
including an appropriate copyright notice and a notice
that there is no warranty (or else, saying that you
provide a warranty) and that users may redistribute
the program under these conditions, and telling the
user how to view a copy of this License. (Exception: if
the Program itself is interactive but does not normally
print such an announcement, your work based on the
Program is not required to print an announcement.)
GNU GENERAL PUBLIC LICENSE
J
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
