2
Preamble
T
he 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 Library 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 modified 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
reflect 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 modification follow.
GNU GENERAL PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. This License applies to any program or other work which 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 modifications and/or translated into another language. (Hereinafter, translation is included without
limitation in the term “modification”.) Each licensee is addressed as “you”.
Activities other than copying, distribution and modification 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.
1. You may copy and distribute verbatim copies of the 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.
2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the
Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided
that you also meet all of these conditions:
