Manual
Table Of Contents
47
To protect each distributor, we want to make it very clear that there is no warranty for the free library. Also, if the library is modied by someone else and
passed on, the recipients should know that what they have is not the original version, so that the original author’s reputaon will not be aected by problems
that might be introduced by others.
Finally, soware patents pose a constant threat to the existence of any free program. We wish to make sure that a company cannot eecvely restrict the
users of a free program by obtaining a restricve license from a patent holder. Therefore, we insist that any patent license obtained for a version of the library
must be consistent with the full freedom of use specied in this license.
Most GNU soware, including some libraries, is covered by the ordinary GNU General Public License. This license, the GNU Lesser General Public License,
applies to certain designated libraries, and is quite dierent from the ordinary General Public License. We use this license for certain libraries in order to
permit linking those libraries into non-free programs.
When a program is linked with a library, whether stacally or using a shared library, the combinaon of the two is legally speaking a combined work, a
derivave of the original library. The ordinary General Public License therefore permits such linking only if the enre combinaon ts its criteria of freedom.
The Lesser General Public License permits more lax criteria for linking other code with the library.
We call this license the “Lesser” General Public License because it does Less to protect the user’s freedom than the ordinary General Public License. It also
provides other free soware developers Less of an advantage over compeng non-free programs. These disadvantages are the reason we use the ordinary
General Public License for many libraries. However, the Lesser license provides advantages in certain special circumstances.
For example, on rare occasions, there may be a special need to encourage the widest possible use of a certain library, so that it becomes a de-facto standard.
To achieve this, non-free programs must be allowed to use the library. A more frequent case is that a free library does the same job as widely used non-free
libraries. In this case, there is lile to gain by liming the free library to free soware only, so we use the Lesser General Public License.
In other cases, permission to use a parcular library in non-free programs enables a greater number of people to use a large body of free soware. For
example, permission to use the GNU C Library in non-free programs enables many more people to use the whole GNU operang system, as well as its variant,
the GNU/Linux operang system.
Although the Lesser General Public License is Less protecve of the users’ freedom, it does ensure that the user of a program that is linked with the Library
has the freedom and the wherewithal to run that program using a modied version of the Library.
The precise terms and condions for copying, distribuon and modicaon follow. Pay close aenon to the dierence between a “work based on the
library” and a “work that uses the library”. The former contains code derived from the library, whereas the laer must be combined with the library in order
to run.
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. This License Agreement applies to any soware library or other program which contains a noce placed by the copyright holder or other authorized party
saying it may be distributed under the terms of this Lesser General Public License (also called “this License”). Each licensee is addressed as “you”.
A “library” means a collecon of soware funcons and/or data prepared so as to be conveniently linked with applicaon programs (which use some of those
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The “Library”, below, refers to any such soware library or work which has been distributed under these terms. A “work based on the Library” means either
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“Source code” for a work means the preferred form of the work for making modicaons to it. For a library, complete source code means all the source code
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Acvies other than copying, distribuon and modicaon are not covered by this License; they are outside its scope. The act of running a program using the
Library is not restricted, and output from such a program is covered only if its contents constute a work based on the Library (independent of the use of the
Library in a tool for wring it). Whether that is true depends on what the Library does and what the program that uses the Library does.
1. You may copy and distribute verbam copies of the Library’s complete source code as you receive it, in any medium, provided that you conspicuously and
appropriately publish on each copy an appropriate copyright noce and disclaimer of warranty; keep intact all the noces that refer to this License and to the
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You may charge a fee for the physical act of transferring a copy, and you may at your opon oer warranty protecon in exchange for a fee.
2. You may modify your copy or copies of the Library or any poron of it, thus forming a work based on the Library, and copy and distribute such
modicaons or work under the terms of Secon 1 above, provided that you also meet all of these condions:
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b) You must cause the les modied to carry prominent noces stang that you changed the les and the date of any change.
c) You must cause the whole of the work to be licensed at no charge to all third pares under the terms of this License.
d) If a facility in the modied Library refers to a funcon or a table of data to be supplied by an applicaon program that uses the facility,
other than as an argument passed when the facility is invoked, then you must make a good faith eort to ensure that, in the event
an applicaon does not supply such funcon or table, the facility sll operates, and performs whatever part of its purpose remains
meaningful.