GNU GENERAL PUBLIC LICENSE
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc. 59
Temple Place, Suite 330, Boston, MA 02111 USA
Everyone is permitted to copy and distribute verbatim copies of
this license document, but changing it is not allowed.
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 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
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
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
a) You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.
b) You must cause any work that you distribute or 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.
c) If the modified program normally reads commands 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
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the
Program, and can be reasonably considered independent and
separate works in themselves, then this License, and its terms,
do not apply to those sections when you distribute them as
separate works. But when you distribute the same sections as
part of a whole which is a work based on the Program, the
distribution of the whole must be on the terms of this License,
whose permissions for other licensees extend to the entire
whole, and thus to each and every part regardless of who wrote
Thus, it is not the intent of this section to claim rights or
contest your rights to work written entirely by you; rather, the
intent is to exercise the right to control the distribution of
derivative or collective works based on the Program.
In addition, mere aggregation of another work not based on the
Program with the Program (or with a work based on the Program)
on a volume of a storage or distribution medium does not bring
the other work under the scope of this License.
3. You may copy and distribute the Program (or a work based on
it, under Section 2) in object code or executable form under the
terms of Sections 1 and 2 above provided that you also do one of
a) Accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of
Sections 1 and 2 above on a medium customarily used for software
b) Accompany it with a written offer, valid for at least three
years, to give any third party, for a charge no more than your
cost of physically performing source distribution, a complete
machine-readable copy of the corresponding source code, to be
distributed under the terms of Sections 1 and 2 above on a
medium customarily used for software interchange; or,
c) Accompany it with the information you received as to the
offer to distribute corresponding source code. (This
alternative is allowed only for non-commercial distribution and
only if you received the program in object code or executable
form with such an offer, in accord with Subsection b above.)
The source code for a work means the preferred form of the work
for making modifications to it. For an executable work,
complete source code means all the source code for all modules
it contains, plus any associated interface definition files,
plus the scripts used to control compilation and installation of
the executable. However, as a special exception, the source
code distributed need not include anything that is normally
distributed (in either source or binary form) with the major
components (compiler, kernel, and so on) of the operating system
on which the executable runs, unless that component itself
accompanies the executable.
If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are
not compelled to copy the source along with the object code.
4. You may not copy, modify, sublicense, or distribute the
Program except as expressly provided under this License. Any
attempt otherwise to copy, modify, sublicense or distribute the
Program is void, and will automatically terminate your rights
under this License. However, parties who have received copies,
or rights, from you under this License will not have their
licenses terminated so long as such parties remain in full
5. You are not required to accept this License, since you have
not signed it. However, nothing else grants you permission to
modify or distribute the Program or its derivative works. These
actions are prohibited by law if you do not accept this License.
Therefore, by modifying or distributing the Program (or any work
based on the Program), you indicate your acceptance of this
License to do so, and all its terms and conditions for copying,
distributing or modifying the Program or works based on it.
6. Each time you redistribute the Program (or any work based on
the Program), the recipient automatically receives a license
from the original licensor to copy, distribute or modify the
Program subject to these terms and conditions. You may not
impose any further restrictions on the recipients' exercise of
the rights granted herein. You are not responsible for
enforcing compliance by third parties to this License.
7. If, as a consequence of a court judgment or allegation of
patent infringement or for any other reason (not limited to
patent issues), conditions are imposed on you (whether by court
order, agreement or otherwise) that contradict the conditions of
this License, they do not excuse you from the conditions of this
License. If you cannot distribute so as to satisfy
simultaneously your obligations under this License and any other
pertinent obligations, then as a consequence you may not
distribute the Program at all. For example, if a patent license
would not permit royalty-free redistribution of the Program by
all those who receive copies directly or indirectly through you,
then the only way you could satisfy both it and this License
would be to refrain entirely from distribution of the Program.
If any portion of this section is held invalid or unenforceable
under any particular circumstance, the balance of the section is
intended to apply and the section as a whole is intended to
apply in other circumstances.
It is not the purpose of this section to induce you to infringe
any patents or other property right claims or to contest
validity of any such claims; this section has the sole purpose
of protecting the integrity of the free software distribution
system, which is implemented by public license practices. Many
people have made generous contributions to the wide range of
software distributed through that system in reliance on
consistent application of that system; it is up to the
author/donor to decide if he or she is willing to distribute
software through any other system and a licensee cannot impose
This section is intended to make thoroughly clear what is
believed to be a consequence of the rest of this License.
8. If the distribution and/or use of the Program is restricted
in certain countries either by patents or by copyrighted
interfaces, the original copyright holder who places the Program
under this License may add an explicit geographical distribution
limitation excluding those countries, so that distribution is
permitted only in or among countries not thus excluded. In such
case, this License incorporates the limitation as if written in
the body of this License.
9. The Free Software Foundation may publish revised and/or new
versions of the General Public License from time to time. Such
new versions will be similar in spirit to the present version,
but may differ in detail to address new problems or concerns.
Each version is given a distinguishing version number. If the
Program specifies a version number of this License which applies
to it and "any later version", you have the option of following
the terms and conditions either of that version or of any later
version published by the Free Software Foundation. If the
Program does not specify a version number of this License, you
may choose any version ever published by the Free Software
10. If you wish to incorporate parts of the Program into other
free programs whose distribution conditions are different, write
to the author to ask for permission. For software which is
copyrighted by the Free Software Foundation, write to the Free
Software Foundation; we sometimes make exceptions for this. Our
decision will be guided by the two goals of preserving the free
status of all derivatives of our free software and of promoting
the sharing and reuse of software generally.
11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO
WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE
LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT
WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING,
BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE
QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
SERVICING, REPAIR OR CORRECTION.
12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO
IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE
LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS
OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH
ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN
ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
END OF TERMS AND CONDITIONS
Appendix: How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the
greatest possible use to the public, the best way to achieve
this is to make it free software which everyone can redistribute
and change under these terms.
To do so, attach the following notices to the program. It is
safest to attach them to the start of each source file to most
effectively convey the exclusion of warranty; and each file
should have at least the "copyright" line and a pointer to where
the full notice is found.
<one line to give the program's name and a brief idea of what
it does.> Copyright (C) 19yy <name of author>
This program is free software; you can redistribute it
and/or modify it under the terms of the GNU General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public
License along with this program; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
MA 02111 USA
Also add information on how to contact you by electronic and
If the program is interactive, make it output a short notice
like this when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) 19yy name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type
`show w'. This is free software, and you are welcome to
redistribute it under certain conditions; type `show c' for
The hypothetical commands `show w' and `show c' should show the
appropriate parts of the General Public License. Of course, the
commands you use may be called something other than `show w' and
`show c'; they could even be mouse-clicks or menu
items--whatever suits your program.
You should also get your employer (if you work as a programmer)
or your school, if any, to sign a "copyright disclaimer" for the
program, if necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the
program `Gnomovision' (which makes passes at compilers) written
by James Hacker.
<signature of Ty Coon>, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your
program into proprietary programs. If your program is a
subroutine library, you may consider it more useful to permit
linking proprietary applications with the library. If this is
what you want to do, use the GNU Library General Public License
instead of this License.