Filter
Top Products
61EN
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 License therefore permits such linking only if the entire combination fits 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 software developers Less of an
advantage over competing 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 little to gain by limiting the free library to free software only, so we use the
Lesser General Public License.
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 License 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.
GNU LESSER GENERAL PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. This License 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 License (also called "this License"). Each licensee is addressed as "you".
A "library" means a collection of software functions and/or data prepared so as to be conveniently
linked with application programs (which use some of those functions and data) to form executables.
The "Library", below, refers to any such software library or work which has been distributed under these
terms. A "work based on the Library" means either the Library or any derivative work under copyright
law: that is to say, a work containing the Library or a portion of it, either verbatim or with modifications
and/or translated straightforwardly into another language. (Hereinafter, translation is included without
limitation in the term "modification".)
"Source code" for a work means the preferred form of the work for making modifications to it. For a
library, 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 library.
Activities other than copying, distribution and modification 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 constitute a work based on the Library (independent of the use
of the Library in a tool for writing 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 verbatim 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 notice and disclaimer of warranty; keep intact all the notices that refer to this License and to
the absence of any warranty; and distribute a copy of this License along with the Library.
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 Library or any portion of it, thus forming a work based on
the Library, 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) The modified work must itself be a software library.
b) You must cause the files modified to carry prominent notices stating that you changed the files and
the date of any change.
c) You must cause the whole of the work to be licensed at no charge to all third parties under the terms
of this License.
d) If a facility in the modified Library refers to a function or a table of data to be supplied by an
application program that uses the facility, other than as an argument passed when the facility is
invoked, then you must make a good faith effort to ensure that, in the event an application does not
supply such function or table, the facility still operates, and performs whatever part of its purpose
remains meaningful.
(For example, a function in a library to compute square roots has a purpose that is entirely well-
defined independent of the application. Therefore, Subsection 2d requires that any application-
supplied function or table used by this function must be optional: if the application does not supply
it, the square root function must still compute square roots.)
These requirements apply to the modified work as a whole. If identifiable sections of that work are not
derived from the Library, 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 Library, 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 Library.
In addition, mere aggregation of another work not based on the Library with the Library (or with a work
based on the Library) on a volume of a storage or distribution medium does not bring the other work
under the scope of this License.
3. You may opt to apply the terms of the ordinary GNU General Public License instead of this License to a
given copy of the Library. To do this, you must alter all the notices that refer to this License, so that they
refer to the ordinary GNU General Public License, version 2, instead of to this License. (If a newer version
than version 2 of the ordinary GNU General Public License has appeared, then you can specify that
version instead if you wish.) Do not make any other change in these notices.
Once this change is made in a given copy, it is irreversible for that copy, so the ordinary GNU General
Public License applies to all subsequent copies and derivative works made from that copy.
This option is useful when you wish to copy part of the code of the Library into a program that is not a
library.
4. You may copy and distribute the Library (or a portion or derivative of it, under Section 2) in object code
or executable form under the terms of Sections 1 and 2 above provided that you 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.
If distribution of 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 satisfies the requirement to distribute the
source code, even though third parties are not compelled to copy the source along with the object code.
5. A program that contains no derivative of any portion of the Library, but is designed to work with the
Library by being compiled or linked with it, is called a "work that uses the Library". Such a work, in
isolation, is not a derivative work of the Library, and therefore falls outside the scope of this License.
However, linking a "work that uses the Library" with the Library creates an executable that is a derivative
of the Library (because it contains portions of the Library), rather than a "work that uses the library". The
executable is therefore covered by this License. Section 6 states terms for distribution of such
executables.
When a "work that uses the Library" uses material from a header file that is part of the Library, the object
code for the work may be a derivative work of the Library even though the source code is not. Whether
this is true is especially significant if the work can be linked without the Library, or if the work is itself a
library. The threshold for this to be true is not precisely defined by law.
If such an object file uses only numerical parameters, data structure layouts and accessors, and small
macros and small inline functions (ten lines or less in length), then the use of the object file is
unrestricted, regardless of whether it is legally a derivative work. (Executables containing this object
code plus portions of the Library will still fall under Section 6.)
Otherwise, if the work is a derivative of the Library, you may distribute the object code for the work
under the terms of Section 6. Any executables containing that work also fall under Section 6, whether or
not they are linked directly with the Library itself.
6. As an exception to the Sections above, you may also combine or link a "work that uses the Library" with
the Library to produce a work containing portions of the Library, and distribute that work under terms
of your choice, provided that the terms permit modification of the work for the customer's own use and
reverse engineering for debugging such modifications.
You must give prominent notice with each copy of the work that the Library is used in it and that the
Library and its use are covered by this License. You must supply a copy of this License. If the work during
execution displays copyright notices, you must include the copyright notice for the Library among
them, as well as a reference directing the user to the copy of this License. Also, you must do one of these
things:
a) Accompany the work with the complete corresponding machine-readable source code for the Library
including whatever changes were used in the work (which must be distributed under Sections 1 and 2
above); and, if the work is an executable linked with the Library, with the complete machine-readable
"work that uses the Library", as object code and/or source code, so that the user can modify the
Library and then relink to produce a modified executable containing the modified Library. (It is
understood that the user who changes the contents of definitions files in the Library will not
necessarily be able to recompile the application to use the modified definitions.)
b) Use a suitable shared library mechanism for linking with the Library. A suitable mechanism is one that
(1) uses at run time a copy of the library already present on the user's computer system, rather than
copying library functions into the executable, and (2) will operate properly with a modified version of
the library, if the user installs one, as long as the modified version is interface-compatible with the
version that the work was made with.
c) Accompany the work with a written offer, valid for at least three years, to give the same user the
materials specified in Subsection 6a, above, for a charge no more than the cost of performing this
distribution.
d) If distribution of the work is made by offering access to copy from a designated place, offer
equivalent access to copy the above specified materials from the same place.
e) Verify that the user has already received a copy of these materials or that you have already sent this
user a copy.
For an executable, the required form of the "work that uses the Library" must include any data and
utility programs needed for reproducing the executable from it. However, as a special exception, the
materials to be 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.
It may happen that this requirement contradicts the license restrictions of other proprietary libraries
that do not normally accompany the operating system. Such a contradiction means you cannot use
both them and the Library together in an executable that you distribute.
7. You may place library facilities that are a work based on the Library side-by-side in a single library
together with other library facilities not covered by this License, and distribute such a combined library,
provided that the separate distribution of the work based on the Library and of the other library
facilities is otherwise permitted, and provided that you do these two things:
a) Accompany the combined library with a copy of the same work based on the Library, uncombined
with any other library facilities. This must be distributed under the terms of the Sections above.
b) Give prominent notice with the combined library of the fact that part of it is a work based on the
Library, and explaining where to find the accompanying uncombined form of the same work.
8. You may not copy, modify, sublicense, link with, or distribute the Library except as expressly provided
under this License. Any attempt otherwise to copy, modify, sublicense, link with, or distribute the
Library 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.
9. 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 Library or its derivative works. These actions are prohibited
by law if you do not accept this License. Therefore, by modifying or distributing the Library (or any work
based on the Library), you indicate your acceptance of this License to do so, and all its terms and
conditions for copying, distributing or modifying the Library or works based on it.
10. Each time you redistribute the Library (or any work based on the Library), the recipient automatically
receives a license from the original licensor to copy, distribute, link with or modify the Library 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 with
this License.