GPLv2: Section by Section
Table of Contents
Introduction
The goal of this article is to explain the terms and
conditions of the GNU General Public License, version
2.0, by stepping through the license section by
section.
You can find a copy of GPLv2 on this server
as well as on gnu.org
I am not a lawyer, this is not legal advice.
Name, Version, and Date
The text of GPLv2 starts with the name of the license,
its version, and the year it was published:
GNU GENERAL PUBLIC LICENSE
Version 2, June 1991
Note that the year of publication is 1991. While the
underlying principles of software freedom and copyleft
have remained as important and relevant
as ever, it is worth keeping in mind that GPLv2 is over
30 years old.
Copyright notice and
the "License of the License"
The copyright notice shows that the copyright holder is
the Free Software Foundation. Following the copyright
notice is a short "verbatim-only" copyright
license:
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.
This explains that you may copy the text of the
license, but you may not modify it. This is in an effort
to ensure that when you or someone else gets a copy of
the license, it will contain the same terms as any other
copy of the license.
Preamble
The preamble is a part of the text of GPLv2 but it is
not a part of the terms and conditions of the
license. Instead, the preamble is a vernacular
explanation of the intent of the license:
Preamble
The licenses for most software are designed to take away your
freedom to share and change it. By contrast...
Reading the preamble is useful for understanding the
GPL and copyleft in general, but as the preamble states: "The precise terms and conditions for copying,
distribution and modification follow."
Beginning and End
As opposed to the top and bottom matter such as the
preamble, and the "How to Apply These Terms" part at
the bottom, the actual terms and conditions of GPLv2
start at the text:
GNU GENERAL PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
...and continue through to the text (found after
section 12):
END OF TERMS AND CONDITIONS
Indeed, it is in this part of the of text, the terms
and conditions, that we will be focusing our attention.
Section 0
For reference, here is the text of section 0 of
GPLv2:
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.
Section 0 addresses the following questions:
- What does the license apply to?
- How much of the work does the license cover?
- Which activities does the license cover?
- Does the license cover the output of a program?
I. What does the license apply to?
The license applies to any program or work that has a
notice on it declaring that it is under GPLv2. Only the
copyright holder of the work is allowed to place such a
notice, and nobody but the copyright holder can change
or remove it.
II. How much of the work does the license
cover?
Section 0 states that the license covers the
following:
- The entire work.
- Any work which would be considered a derivative
of the work under copyright law. Note that what is
considered a derivative is defined by law and not by the
GPL; you won't find a definition of "derivative" in
the GPL.
- Anything that contains any portion of the work,
either modified or as-is. For example: copy-pasting code
from a GPL'd work, or giving a compiler or interpreter a
directive to include a GPL'd work (which is simply asking
the machine to do the copying and pasting for you.)
- A translation of the work to another
language.
III. Which activities does the license cover?
The GPLv2 covers copying, distribution, and
modification. Running the program is explicitly not
covered by the license.
IV. Does the license cover the output of a
program?
The output of the program isn't covered by the license,
unless that output contains portions or derivatives of
the code.
Section 1
Here is the text of section 1 of GPLv2:
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.
Section 1 answers the following questions:
- Am I allowed to distribute unmodified copies of
the the source code of the program?
- Can I charge money for distributing a copy?
- Can I offer a warranty for a fee?
I. Am I allowed to distribute
unmodified copies of the source code?
Section 1 of GPLv2 states that you are allowed to make
copies of the unmodified source code of the program and
distribute them in any medium, as long as you comply
with a number of conditions.
Note that this section doesn't mention binaries.
This only applies to source code, and unmodified source
code at that. Also note that this is permitted
in any medium. Which would include, for
example, giving someone a copy on a hard-disk, over the
Internet, a paper printout, transmitted over
software-controlled radio, printed on a t-shirt, etc.
You can do the above only if you comply with a number
of conditions. You must do all of the following:
- publish all the appropriate copyright notices
- publish the disclaimer of warranty
- keep intact notices that refer to GPLv2
- keep intact the notices stating the absence of
any warranty
- give a copy of the GPLv2 license text to anyone
you give the work
II. Can I charge money for
distributing a copy?
Yes, you may charge money for giving someone a
copy. Since they get the copy under the terms of GPLv2
as well, it means that they in turn can charge money, if
they wish, for further distributing the software under
GPLv2.
III. Can I offer a warranty for
a fee?
Yes, you may offer a warranty for a fee, and so may
anyone to whom you give the software if they further
distribute it.
Section 2
What follows is the text of section 2 of GPLv2:
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:
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 announcement.)
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 it.
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.
Section 2 is a heavy-hitter, and deals with the
following questions:
- Am I allowed to distribute a modified version of
the work?
- What do I need to do when I modify a file in the
work?
- What do I need to distribute, and what of that
does the license cover?
- Can I charge for licensing?
- Does the user interface need to state that the
program is licensed under the terms of the GPL?
- Which parts of the work are not covered by
GPLv2?
First, an important note on how GPLv2 works. Note the
following text from the beginning of section 2:
...under the terms of Section 1 above, provided that
you also...
Section 2 builds on section 1. You will see going
forward that each section of GPLv2 builds on all of the
previous sections. Thus, there is no way to be in
compliance with section 2, without first abiding by the
conditions of section 1. The same will be true of all
the proceeding sections.
Also, keep in mind that like the preceding section,
section 2 doesn't address binaries; we are still
focusing on just the source code.
I. Am I allowed to distribute a
modified version of the work?
Yes, you are allowed to modify the source code and
distribute the modification as long as you comply with
section 1 (see above), and also meet all of the
conditions of sections 2(a), 2(b) and 2(c).
II. What do I need to do when I
modify the work?
Section 2(a)
You need to place a notice in each file you've changed
showing that you've modified it, and when you did so. An
accepted way of doing this is to add your copyright
notice to the top of the file. This process is important
enough to warrant a separate article
with the details.
III. What do I need to
distribute, and what of that does the license cover?
Section 2(b)
Section 2(b) requires you to distribute the entire work
under the terms of GPLv2. This means that the following
would have to be distributed under the terms of the
license:
- the entire program
- any part/portion of the program
- any derivative of the program
- any derivative of any part/portion of the program
As you can see, this includes pretty much
everything. This is one of the reasons why the GPL is
called a "strong" copyleft license.
IV. Can I charge for licensing?
The short answer is no. Read on for the not-so-short
answer:
Section 2(b) of GPLv2 contains the condition that
the distributed program "be licensed as a whole at no charge to all
third parties under the terms of this
License". This means that while, as per section 1
of GPLv2, you can charge money for the physical act of
giving someone a copy of the program, you cannot charge
money for that copy being under GPLv2.
What does that last part mean, exactly? Let us use a
hypothetical example: suppose that you have a copy of
the program FOO, and that FOO is licensed under the terms
of GPLv2.
As per section 1 of GPLv2, you can distribute copies of
FOO and charge $200 for each copy, and each recipient
gets their copy under the terms of GPLv2. Each recipient
is then free to (among other things) further distribute
their copies of FOO in return for a fee, or gratis and
at no charge.
But as per section 2 of GPLv2, you cannot distribute
copies of FOO and tell people that if they don't pay
then their copy will not be under GPLv2. To put it
another way, you cannot say "You can have a copy, but
you can have it under the terms of GPLv2 only if you pay
me."
If we take sections 1 and 2 together, we understand
that no matter if we charge for distributing a
GPLv2-licensed work, or distribute it gratis and at no
cost, the work remains under GPLv2. Whether the
recipient gets it under the terms of GPLv2 isn't up to
us; it is always under GPLv2 no matter what.
V. Does the user interface need
to state that the program is licensed under the terms of
the GPL?
Section 2(c)
If the user interface of the program displays an
announcement that the software is licensed under the
GPL, along with copyright and warranty information, then
you need to preserve that notice and update it as
needed (for example, if you are offering a specific
warranty with your copy.) But you don't need to add such
an announcement if none was there to begin with. These
announcements typically look something like this (text
taken from the HOW-TO section at the bottom of GPLv2):
Gnomovision version 69, Copyright (C) year 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 details.
VI. Which parts of the work are
not covered by GPLv2?
Section 2 - the last three paragraphs
The last three paragraphs of section 2 of GPLv2 go into
the fine details of derivatives, compatibility, and
rights. This part of GPLv2 contains some subtle points
that are often misunderstood, and demands careful
reading.
We will deal with the text piecemeal, starting with
this:
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. ...
What does this mean, and how does it relate to the
requirement in section 2(b) to distribute the entire
work under GPLv2?
It means that if you have an independent work that is
distributed separately from the GPLv2-licensed program,
then that independent work doesn't have to be
distributed under the terms of GPLv2 just because a
GPLv2-licensed program uses it.
As long as they are separate and
independently-developed programs, then the fact that the
one is under the terms of GPLv2 doesn't affect the
other.
This brings us to the next part:
... 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 it.
That means that when you distribute that same
independently-developed program as a part of your
GPLv2-licensed work (for example, as a library) then the
terms of GPLv2 apply to the work as a whole.
It is important to stress the fact that this applies
only to when you distribute the work as a whole. GPLv2
doesn't change the license of the
independently-developed parts. Instead, GPLv2 determines
under which terms the work as a whole is being
distributed. The license makes this point here:
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.
Section 2 ends with a statement about aggregate works,
making clear that merely adding an otherwise unrelated
GPLv2-licensed work to a disk or other storage medium
doesn't affect the license of everything else on that
disk.
Section 3
Here is the text of section 3 of GPLv2:
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 the following:
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 interchange; or,
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 noncommercial 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.
Section 3 provides answers for the following:
- Am I allowed to distribute a program, either
modified or unmodified, as a binary?
- How does GPLv2 define source code?
- What isn't considered source code?
- Do I always have to package the source code with
the binary?
Section 3 builds upon the source code requirements of
sections 1 and 2, and introduces conditions for
distributing object code, aka binaries. Section 3
achieves something that is at the heart of the GPL,
which is to ensure that if someone gets an executable or
binary, they also get the corresponding source code.
I. Am I allowed to distribute a
program, either modified or unmodified, as a binary?
Yes, you are allowed to distribute a program or a
modified version of that program as a binary if you
abide by the terms of sections 1 and 2, and also do one
of either section 3(a), 3(b), or 3(c). Which one of
sections 3(a), 3(b), or 3(c) you choose depends on your
situation, and it is up to you to choose the one you can
fulfill.
Section 3(a) of GPLv2 reads:
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 interchange ...
Section 3(a) provides the most straightforward way of
fulfilling the requirement to provide source code along
with a binary: when you give someone the binary, give
them the source code as well.
The source code is required to be "corresponding" to
the binary. This means that the recipient should be able
to use that source code to produce a binary similar to
the one you distributed. It isn't technically feasible
to demand that the source code be able to produce an
exact and bit-perfect copy of the binary, and so the GPL
doesn't require that.
The source code is also required to be
"machine-readable". This requirement helps ensure that
the source code is in a format that the recipient can
actually use in a practical way to produce their own
binary.
You are still free to provide the source code in any
medium, as in section 1, but if you are providing the
corresponding source for a binary, then that medium and
format must be machine-readable.
Section 3(b) is much more involved. It should quickly
become clear why section 3(a) is preferable unless you
have no choice but to rely on section 3(b):
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...
This permits you distribute the program with an offer
to provide the source on demand, under the following
conditions:
- You have to honor the offer for the next three
years (the clock starts when you distribute the
binary).
- Anyone (yes, anyone) who has a copy of the offer
can ask for the source code from you, and you'll have to
give it to them.
- You can't charge money for giving anyone the
source code in this way, beyond what it would cost you
to physically do it.
Section 3(c) deals with an edge case:
c) Accompany it with the information you received as to
the offer to distribute corresponding source code. (This
alternative is allowed only for noncommercial distribution and
only if you received the program in object code or executable
form with such an offer, in accord with Subsection b above.)
Section 3(c) states that if you've received a binary
from someone along with an offer for the source code (as
above), and you simply want to share that binary with
someone, then you can pass along that offer along with
the binary. Section 3(c) states that this can't be done
commercially, so you can't really have this be part of
your business model; this is more about helping our your
neighbor.
II. How does GPLv2 define
source code?
Section 3 requires that you accompany a binary with its
corresponding source code, so it is important to define
exactly that is. We'll look at the next part of section 3
piece by piece, starting with:
The source code for a work means the preferred form of
the work for making modifications to it.
This helps ensure the source code is provided in a way
that the recipient can actually use to study, modify,
and compile into a binary.
Next, section 3 provides a complete definition of what
is considered the source code for a given binary:
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.
This definition covers everything a programmer
needs. It starts with all of the source code for every
part of the binary, then adds the interface files that
connect all of those parts together, the code required
to compile it all, and finally the scripts that control
installation.
III. What isn't considered
source code?
The above definition of source code includes libraries
which are part of the operating system and serve to
allow the program to interact with the operating system
and its major components; we call these "system
libraries". It may not be possible for you to
distribute the system libraries in question. Therefore
GPLv2 has a system library exception:
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.
The system library exception means you don't need to
distribute the source code to anything that would be
considered a system library, unless you distribute that
system library alongside the binary.
IV. Do I always have to package
the source code with the binary?
No, that isn't always necessary. For instance, you can
offer a link to the binary, and also an equivalent link
to the source. Section 3 ends with a detailed
explanation:
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.
You don't even need to ensure that the recipients of
the binary also grabbed a copy of the source. It's your
job to make the source available, but you don't need to
force anyone to take it.
Section 4
Here is section 4 of GPLv2:
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
compliance.
Section 4 answers the following questions:
- Does GPLv2 permit any other ways to copy, modify, sublicense, or distribute the Program?
- What would happen if I copied, modified, sublicensed, or distributed the work in a way GPLv2 doesn't permit?
- If my rights under GPLv2 are terminated for the work, what happens to the rights of people to whom I gave copies of the work?
I. Does GPLv2 permit any other
ways to copy, modify, sublicense, or distribute the
Program?
No. The first part of section 4 makes it clear that
your only options to do any of those things with the
program are those detailed in the license:
You may not copy, modify, sublicense, or distribute the
Program except as expressly provided under this License.
II. What would happen if I
copied, modified, sublicensed, or distributed the program in a
way GPLv2 doesn't permit?
If you did any of those things with the work in a way
GPLv2 doesn't permit then the license immediately and
automatically becomes void for you. You lose all of the
permissions GPLv2 granted; your license is terminated:
Any attempt otherwise to copy, modify, sublicense or
distribute the Program is void, and will automatically terminate
your rights under this License.
With GPLv2 this happens immediately. There is no grace
period. It also happens automatically, that is, the
copyright holder of the program doesn't need to do
anything to trigger it.
III. If my rights under GPLv2
are terminated for the program, what happens to the
rights of people to whom I gave copies of the program?
As long as they continue to abide by the terms of the
license they can enjoy the permissions granted by the
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 compliance.
Section 5
Next, let's examine section 5 of GPLv2:
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.
Section 5 deals with the following questions:
- What if I don't accept the license?
- How do I accept the license?
I. What if I don't accept the license?
If you don't accept the conditions of GPLv2 then you
can't modify or distribute the program. GPLv2 doesn't
require you to accept the license, but it also doesn't
confer any rights to you unless you accept its terms:
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.
II. How do I accept the license?
Under the terms of GPLv2, you show that you accept the
terms of the license by modifying or distributing the
work or its derivatives:
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.
Section 6
Section 6 of GPLv2 reads:
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.
Section 6 of GPLv2 answers the following:
- Under which terms do people receive copies of the work I distribute?
- Can I add any restrictions of my own when I distribute the work?
- When I give someone a copy of the work, am I then responsible for them complying with the license?
I. Under which terms do people receive copies of the work I distribute?
Section 6 of GPLv2 states that when you further
distribute the work, the recipient gets a license from
the copyright holder:
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.
Even if you are doing the distribution, the recipient
isn't getting a license from you but from the copyright
holder (the so-called "original licensor".)
II. Can I add any restrictions of my own when I distribute the work?
No, you cannot add any restrictions when you further
distribute your copy of the work. Section 6 states that:
You may not impose any further restrictions on the
recipients' exercise of the rights granted herein.
This makes sense in light of the previous question: you
aren't the licensor and so you can't modify the
license.
III. When I give someone a copy of the work, am I then responsible for them complying with the license?
No, you are not responsible for what other people do
with the work. In the same manner, the person who gave
you your copy of the work isn't responsible if you
violate the license:
You are not responsible for enforcing compliance by
third parties to this License.
Section 7
Section 7 of GPLv2 is as follows:
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 that choice.
This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.
Section 7 of GPLv2 deals with a single question:
I. What if I'm legally prohibited from doing what GPLv2 requires of me?
If you can't legally distribute the work under the
terms of GPLv2, then you can't distribute the work at
all. For example, if you have a court order against you,
or a law in your local jurisdiction, or a similar
external restriction that prohibits you from
distributing the corresponding source to the work (or
complying with any other requirement of GPLv2), then you
can't distribute any of the work in any form.
Section 8
Section 8 of GPLv2 reads:
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.
Section 8 of GPLv2, like the previous section, answers a single question:
I. Can a work under GPLv2 restrict to which countries the work can be distributed?
Yes, it can. If the copyright holder of a work placed a
geographical restriction on their work because of patent
or copyright laws then you will have to treat that
restriction as if it was part of GPLv2.
Take note that this only applies to the copyright
holder of the work. If you have similar restrictions
then you cannot add any terms of the license.
Section 9
Section 9 of GPLv2 states:
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
Foundation.
Section 9 of GPLv2 answers the following questions:
- I. Will the Free Software Foundation publish newer versions of the GPL? If so, what kind of license will that be?
- II. Can I upgrade from an older version of the GPL to a newer one?
- III. What if my copy doesn't specify which version of the GPL it is under?
I. Will the Free Software Foundation publish newer versions of the GPL? If so, what kind of license will that be?
GPLv2 contains within it a promise to the free software
community that future versions of the GPL will have the
same goals:
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.
II. Can I upgrade from an older version of the GPL to a newer one?
Yes, you can upgrade a work from GPLv2 to a later
version of the GPL, but only if the copyright holder of
the work permitted it by explicitly stating that the
work is under GPLv2 "or later":
... 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.
III. What if my copy doesn't specify which version of the GPL it is under?
If your copy doesn't specify a version then you are
free to choose any version of the GPL:
If the Program does not specify a version number of
this License, you may choose any version ever published by the
Free Software Foundation.
Section 10
Section 10 of GPLv2 reads:
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.
Section 10 of GPLv2 concentrates on a single question:
I. What if I want to incorporate the work into my incompatibly-licensed program?
You can't do that, but you can contact the copyright
holder of the work and ask for their permission.
Section 11
Section 11 of GPLv2 emphatically states:
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.
This section leaves little doubt about the follow question:
I. What kind of warranty does the work have?
The answer is: absolutely none. GPLv2 disclaims any
warranty to the fullest extent possible. Remember though
that as per section 1 you are free to offer a different
kind of warranty.
Section 12
Section 11 of GPLv2 unequivocally proclaims the following:
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.
This section certainly settles the question:
I. What kind of liability coverage does the work have?
As in section 11, the answer is: none. GPLv2 disclaims
liability to the fullest extent it can.
The End
GPLv2 ends with the text:
END OF TERMS AND CONDITIONS
Everything beyond that is useful advice about applying
the license to your work.
Conclusion
GPLv2 is the most important free software license in
the world. More pieces of critical software such as
kernels, compilers, toolchains, etc., use GPLv2 than any
other single license. GPLv2 is the standard for free
software licensing, and is likely to remain so for the
foreseeable future. GPLv2 is also responsible for
popularizing the concept of copyleft, and provided
critical infrastructure for the growing free software
movement.