Filter
Top Products
GNU Lesser General Public Licence (LGPL)
Version 2.1, February 1999
Copyright (C) 1991, 1999 Free Software Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Everyone is permitted
to copy and distribute verbatim copies of this licence document, but changing it is not allowed.
[This is the first released version of the Lesser GPL. It also counts as the successor of the GNU Library Public Licence, version 2, hence the
version number 2.1.]
Preamble
The licences for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public Licences are
intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users.
This licence, the Lesser General Public Licence, applies to some specially designated software packages--typically libraries--of the Free Software
Foundation and other authors who decide to use it. You can use it too, but we suggest you first think carefully about whether this licence or the
ordinary General Public Licence is the better strategy to use in any particular case, based on the explanations below.
When we speak of free software, we are referring to freedom of use, not price. Our General Public Licences 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 and use pieces of it in new free programs; and that you are informed that you can do these things.
To protect your rights, we need to make restrictions that forbid distributors to deny you these rights or to ask you to surrender these rights. These
restrictions translate to certain responsibilities for you if you distribute copies of the library or if you modify it.
For example, if you distribute copies of the library, whether gratis or for a fee, you must give the recipients all the rights that we gave you. You must
make sure that they, too, receive or can get the source code. If you link other code with the library, you must provide complete object files to the
recipients, so that they can relink them with the library after making changes to the library and recompiling it. And you must show them these terms
so they know their rights.
We protect your rights with a two-step method: (1) we copyright the library, and (2) we offer you this licence, which gives you legal permission to
copy, distribute and/or modify the library.
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 modified 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 reputation will not be affected
by problems that might be introduced by others.
Finally, software patents pose a constant threat to the existence of any free program. We wish to make sure that a company cannot effectively
restrict the users of a free program by obtaining a restrictive licence from a patent holder. Therefore, we insist that any patent licence obtained for a
version of the library must be consistent with the full freedom of use specified in this licence.
Most GNU software, including some libraries, is covered by the ordinary GNU General Public Licence. This licence, the GNU Lesser General Public
Licence, applies to certain designated libraries, and is quite different from the ordinary General Public Licence. We use this licence for certain libraries
in order to permit linking those libraries into non-free programs.
When a program is linked with a library, whether statically or using a shared library, the combination of the two is legally speaking a combined work,
a derivative of the original library. The ordinary General Public Licence therefore permits such linking only if the entire combination fits its criteria of
freedom.
The Lesser General Public Licence permits more lax criteria for linking other code with the library.
We call this licence the “Lesser” General Public Licence because it does Less to protect the user’s freedom than the ordinary General Public
Licence. It also provides other free software developers Less of an advantage over competing non-free programs. These disadvantages are
the reason we use the ordinary General Public Licence for many libraries. However, the Lesser licence 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 little to gain by limiting the free library to free software only, so we use the Lesser General Public
Licence.
In other cases, permission to use a particular library in non-free programs enables a greater number of people to use a large body of free software.
For example, permission to use the GNU C Library in non-free programs enables many more people to use the whole GNU operating system, as
well as its variant, the GNU/Linux operating system.
Although the Lesser General Public Licence is Less protective 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 modified version of the Library.
The precise terms and conditions for copying, distribution and modification follow. Pay close attention to the difference between a “work based
on the library” and a “work that uses the library”. The former contains code derived from the library, whereas the latter must be combined with the
library in order to run.
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. This Licence Agreement applies to any software library or other program which contains a notice placed by the copyright holder or other
authorized party saying it may be distributed under the terms of this Lesser General Public Licence (also called “this Licence”). Each licencee is