LDP/LDP/retired/GNU-Build-System-HOWTO/GNU-Build-System-HOWTO.xml

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<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
The version history of this document, along with the comments is at the
end of the file.
Last modification info:
$Id$
-->
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [
<!ENTITY make "<command>make</command>">
<!ENTITY autoconf "<command>autoconf</command>">
<!ENTITY automake "<command>automake</command>">
<!ENTITY libtool "<command>libtool</command>">
<!ENTITY libtoolize "<command>libtoolize</command>">
<!ENTITY configure_cmd "<command>configure</command>">
<!ENTITY m4 "<command>m4</command>">
<!ENTITY makefile "<filename>Makefile</filename>">
<!ENTITY makefile_in "<filename>Makefile.in</filename>">
<!ENTITY makefile_am "<filename>Makefile.am</filename>">
<!ENTITY configure_in "<filename>configure.in</filename>">
<!ENTITY configure_file "<filename>configure</filename>">
<!ENTITY cmdline "<prompt>[jrh ~/gbs]$ </prompt>">
<!ENTITY howto "http://tldp.org/HOWTO/">
<!ENTITY gnu "http://www.gnu.org/">
]>
<article>
<articleinfo>
<!-- Use "HOWTO", "mini HOWTO", "FAQ" in title, if appropriate -->
<title>GNU-Build-System HOWTO</title>
<titleabbrev>GBS-HOWTO</titleabbrev>
<copyright>
<year>2003</year>
<holder>Mark Hoebeke</holder>
<holder>Y Giridhar Appaji Nag</holder>
</copyright>
<authorgroup>
<author>
<firstname>Giridhar</firstname>
<othername>Appaji Nag</othername>
<surname>Y</surname>
<affiliation>
<address>
<email>appaji{at}ibiblio{dot}org</email>
</address>
</affiliation>
</author>
<author>
<firstname>Mark</firstname>
<othername></othername>
<surname>Hoebeke</surname>
<affiliation>
<address>
<email>mark{dot}hoebeke{at}orange{dot}fr</email>
</address>
</affiliation>
</author>
</authorgroup>
<!-- All dates specified in ISO "YYYY-MM-DD" format -->
<pubdate>None Yet!</pubdate>
<!-- Most recent revision goes at the top; list in descending order -->
<revhistory>
<revision>
<revnumber>0.1</revnumber>
<date>2003-11-05</date>
<authorinitials>mh</authorinitials>
<revremark>first formatting of consensus TOC</revremark>
</revision>
</revhistory>
<!-- Provide a good abstract; a couple of sentences is sufficient -->
<abstract>
<para>
This HOWTO aims to help beginning developers to leverage the power
the GNU Build System (GBS). The GBS is composed of well-known
tools such as &make; and of less-used utilities such as
&autoconf;, &automake; or &libtool;. The primary goal of the
HOWTO is to ring developers up to speed with each of these tools,
and, at another level to explain some of their inner workings.
</para>
<para>
Document last updated $Date$.
</para>
</abstract>
</articleinfo>
<!-- Content follows...include introduction, license information -->
<sect1 id="introduction">
<title>Introduction</title>
<sect2 id="about-howto">
<title>About this HOWTO</title>
<para>
If you ever installed packages from source on a Unix environment,
you will have encountered &makefile; that is used to compile the
package. When there was no &automake; or &autoconf;, it was a non
trivial task to get big source packages to compile, leave alone
getting them to work for you. It often involved tweaking of the
&makefile; and making changes to source. Finding the necessary
things that you need (like libraries, the right version of the
library needed) before you could compile a particular package, was
a difficult task.
</para>
<para>
Another major problem that many software developers face is that
of maintaining portability, achieving platform independence and
building libraries. This is important if the code written should
run on a variety of platforms. Finding the specifics of a machine
and the operating system, and configuring the source of a package
for successful compilation and working, is also a problem of
interest.
</para>
<para>
The GNU Autotools address these issues. This HOWTO is a resource
for first time users of the <emphasis>autotools</emphasis>. It is
intended to be an introductory guide, to help with GNU &make;,
&autoconf;, &automake; &libtool; etc. It also tries to provide an
explanation as to how these tools work. To be able to follow
the explanations given in here, the reader is expected to be
familiar with Unix like operating systems and the basics of
programming.
</para>
</sect2>
<sect2 id="latest-version">
<title>Keeping up-to-date</title>
<para>
New versions of this document that are released would be available
from The LDP website and its mirrors. Since a few mirrors are
broken or not up-to-date, it is highly recommended that the latest
released version be accessed from <ulink
url="&howto;GNU-Build-System-HOWTO/">
http://tldp.org/HOWTO/GNU-Build-System-HOWTO/</ulink>. The latest
in-progress version of this document is available at the <ulink
url="http://www.appaji.net/stuff/gbsh.html">GNU-Build-System HOWTO
home page</ulink>.
</para>
</sect2>
<!-- Legal Sections -->
<sect2 id="license">
<title>Document license</title>
<!-- The LDP recommends, but doesn't require, the GFDL -->
<para>
This document, the <emphasis>GNU-Build-System HOWTO</emphasis>, is
distributed under the terms of the <citetitle>GNU General Public
License</citetitle>. The word <emphasis>Program</emphasis> in the
license is to be interpreted as <emphasis>document</emphasis>. The
term <emphasis>source code</emphasis> refers to the DocBook/XML
format of this document and the term <emphasis>object
code</emphasis> refers to one, many or all the other formats that
this document is available in, after conversion from the
<emphasis>source code</emphasis>.
</para>
<para>
This program is free software; you can redistribute it and/or
modify it under the terms of the <link linkend="gnu-gpl">
<citetitle>GNU General Public License</citetitle></link> as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version. A copy of the
license is available at <ulink
url="http://www.gnu.org/licenses/gpl.txt">
http://www.gnu.org/licenses/gpl.txt</ulink> and can be found in
<xref linkend="gnu-gpl"/>.
</para>
<para>
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
02111-1307 USA
</para>
</sect2>
<sect2 id="disclaimer">
<title>Disclaimer</title>
<para>
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.
</para>
<para>
All copyrights are held by their by their respective owners,
unless specifically noted otherwise. Use of a term in this
document should not be regarded as affecting the validity of any
trademark or service mark. Naming of particular products or
brands should not be seen as endorsements.
</para>
</sect2>
</sect1>
<sect1 id="hello-gbs">
<title>Hello build system!</title>
<para>
The GNU Build System encompasses a number of components that assist
a developer in each stage of the configure, compile and distribute
process. Projects using the suite of the GBS are recognizable by
the ease with which they are installed. The ubiquitous
<command>./configure &amp;&amp; make &amp;&amp; make
install</command> does it all.
</para>
<para>
This section of the document introduces the build tools and explains
how to use them. Though the treatment would not be in depth, it
should help you understand the files that these tools operate on.
The aim is to take the reader step by step, through the stages
turning a set of source files of a <quote>project</quote> to conform
to the <command>./configure &amp;&amp; make &amp;&amp; make
install</command> mantra. We will work through each of these
components using a <literal>Hello World!</literal> styled example.
</para>
<sect2 id="hello-make">
<title>Hello GNU &make;!</title>
<para>
If you are reading this document, it is possible that you already
have prior experience with the &make; utility. However, any
discussion of the build system would be incomplete without a
mention of &make;.
</para>
<sect3 id="make-whatis">
<title>What is &make;?</title>
<para>
&make; is a utility for automatic compilation of a project's
source code. It is used in projects to find out if the files
(typically C sources) that a certain <quote>target</quote>
(typically object files and executables) depends on have
changed, and re-generates the target. It makes compiling only
the necessary files of a big project as simple as typing
&make;, when a few of them have been modified. The input to
the &make; utility is a &makefile;.
</para>
</sect3>
<sect3 id="make-example">
<title>&make; in action</title>
<para>
A very minimal &makefile; to &make; a program called
<filename>foo</filename> from its C source file,
<filename>foo.c</filename> would look like:
</para>
<screen>
&cmdline;<userinput>cat Makefile</userinput>
foo: foo.c
gcc -o foo foo.c
&cmdline;
</screen>
<para>
The target in this &makefile; is <filename>foo</filename> and it
depends on the <filename>foo.c</filename> dependency. The
second line (command) tells make how to build the target in case
the dependency changes. The command should be on its own line
with a <emphasis>tab</emphasis> character (and
<emphasis>not</emphasis> spaces) before it.
</para>
<para>
The <filename>foo</filename> executable can then be created by
issuing a <command>make foo</command> command in the directory
where the above &makefile; is present.
</para>
<screen>
&cmdline;<userinput>make</userinput>
gcc -o foo foo.c
&cmdline;
</screen>
<para>
A slightly more useful example would be:
</para>
<screen>
&cmdline;<userinput>cat Makefile</userinput>
all: hw
hw: main.o hello.o world.o
gcc main.o hello.o world.o -o hw
world.o: world.c hello.h world.h
gcc -Wall -c hello.c
hello.o: hello.c hello.h
gcc -Wall -c hello.c
world.o: world.c world.h
gcc -Wall -c world.c
clean:
rm -f hw hello.o world.o
&cmdline;
</screen>
<para>
The default target in this &makefile; (which is the first target
that appears in the &makefile;) is <literal>all</literal>.
<literal>all</literal> depends on <literal>hw</literal> which
in-turn depends on <filename>main.o</filename>,
<filename>hello.o</filename> and <filename>world.o</filename>.
These can be <quote>made</quote> using the rules that have been
specified for them respectively. For example,
<filename>hello.o</filename> is created using the command
<command>gcc -Wall -c hello.c</command> whenever
<filename>hello.c</filename> or <filename>hello.h</filename> are
modified.
</para>
<screen>
&cmdline;<userinput>make</userinput>
gcc -Wall -c main.c
gcc -Wall -c hello.c
gcc -Wall -c world.c
gcc main.o hello.o world.o -o hw
&cmdline;
</screen>
<para>
Another invocation of &make; (or <command>make all</command>)
does nothing. This is because none of the files that &make;
looks at have been modified.
</para>
<screen>
&cmdline;<userinput>make all</userinput>
make: Nothing to be done for `all'.
&cmdline;
</screen>
<para>
However, if one of the files is changed (say
<filename>hello.h</filename>), &make; will figure out the right
files to be re-compiled (based on the dependencies in the
&makefile;) and generate a new <filename>hw</filename>.
</para>
<screen>
&cmdline;<userinput>touch hello.h</userinput>
&cmdline;<userinput>make all</userinput>
gcc -Wall -c main.c
gcc -Wall -c hello.c
gcc main.o hello.o world.o -o hw
&cmdline;
</screen>
<para>
The other target <literal>clean</literal> in the &makefile; can
be invoked explicitly to remove the target files that have been
generated.
</para>
<screen>
&cmdline;<userinput>make clean</userinput>
rm -f hw main.o hello.o world.o
&cmdline;
</screen>
</sect3>
<sect3 id="make-variables">
<title>Variables in &makefile;s</title>
<para>
A &makefile; can also be written using variables and wild-cards
making it easy to modify and maintain. For example, the above
&makefile; can be re-written as:
</para>
<screen>
&cmdline;<userinput>cat Makefile</userinput>
TARGET = hw
OBJS = main.o hello.o world.o
CC = gcc
CCOPTS = -Wall -c
RM = rm
RMOPTS = -f
all: $(TARGET)
$(TARGET): $(OBJS)
$(CC) $(OBJS) -o $(TARGET)
main.o: main.c hello.h world.h
$(CC) $(CCOPTS) $&lt;
%.o: %.c %.h
$(CC) $(CCOPTS) $&lt;
clean:
$(RM) $(RMOPTS) $(TARGET) $(OBJS)
&cmdline;
</screen>
<para>
Every <literal>$(VARIABLE)</literal> in the &makefile; is
replaced with its value. The generic rule <literal>%.o: %.c
%.h</literal>
<footnote>
<para>
In general, one source file would depend on more than one
header file (like the <filename>main.o</filename>
dependency) and the dependency rule is not as simple as
this. It is infact difficult to keep track of dependencies
on header files and their dependencies with nested includes.
There are ways of handling this (see the manual page of
<command>makedepend</command> on your Linux machine and the
<option>-M</option> option to <command>gcc</command>), but
using &automake; makes this a cake-walk.
</para>
</footnote>
says that each <filename>.o</filename> file is dependent on the
corresponding <filename>.c</filename> and the
<filename>.h</filename> files. <literal>$@</literal> refers to
the current target and <literal>$&lt;</literal> refers to the
first one among the list of dependencies of the current target.
Note that this version of the &makefile; does not need a lot of
modifications if a single source file and the corresponding
header files are added.
</para>
<para>
GNU &make; provides several other useful features like the
<literal>VPATH</literal> directive to locate the source files
that are not co-located with the &makefile;, facility for
sophisticated wildcards, etc. These are described in the <link
linkend="resources"><citetitle>official GNU &make;
manual</citetitle></link>.
</para>
</sect3>
<sect3 id="make-gnumakefile">
<title>A GNU &makefile;</title>
<para>
A &makefile; that goes with software packages that follow the
GNU &makefile; conventions has a few standard targets and
provides useful and commonly used functionality like:
</para>
<itemizedlist>
<listitem>
<para>
<literal>all</literal>: to build the package
</para>
</listitem>
<listitem>
<para>
<literal>clean</literal>: which removes all the generated
files
</para>
</listitem>
<listitem>
<para>
<literal>tags</literal>: generates the TAGS file for source
browsing
</para>
</listitem>
<listitem>
<para>
<literal>check</literal>: which executes any automated test
cases that have been included with the package.
</para>
</listitem>
<listitem>
<para>
<literal>dist</literal>: creates a .tar.gz distribution of
the software package.
</para>
</listitem>
<listitem>
<para>
<literal>install</literal>: installs the compiled binaries,
manual pages, documents at their appropriate location.
</para>
</listitem>
<listitem>
<para>
<literal>uninstall</literal>: removes the files that have
been installed
</para>
</listitem>
</itemizedlist>
<para>
and many more ...
</para>
<para>
Writing the dependencies and rules for these targets is a
non-trivial task and involves some effort. &automake; solves
this problem by generating all the standard targets.
</para>
</sect3>
</sect2>
<sect2 id="hello-autoconf">
<title>Hello &autoconf;!</title>
<sect3 id="autoconf-whatis">
<title>What is &autoconf;?</title>
<para>
We need to rely on other tools to ensure that a project is built
and runs correctly on most flavors of Unix (including Linux of
course). These platform specific parameters are detected by the
&configure_file; script generated by &autoconf;. &autoconf; also
generates a &makefile;. The input to the &configure_file;
script are the &makefile_in; and the &configure_in; files.
</para>
</sect3>
</sect2>
<sect2 id="hello-automake">
<title>Hello &automake;!</title>
<sect3 id="whatis-automake">
<title>What is &automake;?</title>
<para>
The final (?) step to build a well-behaved and distributable
software project is to supply &make; with a set of standard
targets (<xref linkend="make-gnumakefile"/>) and to use a set of
thoroughly tested recipes to build them. This is where
&automake; comes into play. Starting from a high-level
description of the project's components (source files, binaries
to be built, documentation, additional data files) found in a
&makefile_am;, &automake; is capable of generating a suitable
&makefile_in;. This can be used by the &configure_file; script
to generate the &makefile;.
</para>
</sect3>
</sect2>
<sect2 id="hello-libtool">
<title>Hello &libtool;!</title>
<para>
So that's it? Now we've got our GBS compliant project
architecture, isn't it? Indeed, but our toolkit would be
incomplete if we omitted to mention &libtool;.
</para>
<sect3 id="whatis-libtool">
<title>What is &libtool;?</title>
<para>
The &libtool; component favors the use of program libraries
(sets of related object files grouped into a single archive).
These libraries can the be used by all executables of a project,
and in some cases, without being copied in every single
executable. Ways of building libraries vary much from platform
to platform, fortunately, &libtool; simplifies this process,
lifting the burden from the programmer.
</para>
</sect3>
</sect2>
</sect1>
<sect1 id="real-example">
<title>The real world</title>
<para>
After the entry-level guided tour, a real world programming project
will be subjected to the whole above slew of procedures here.
</para>
<sect2 id="example-make">
<title>A real GNU &make; example</title>
<para></para>
</sect2>
<sect2 id="example-autoconf">
<title>A real &autoconf; example</title>
<para></para>
</sect2>
<sect2 id="example-automake">
<title>A real &automake; example</title>
<para></para>
</sect2>
<sect2 id="example-libtool">
<title>A real &libtool; example</title>
<para></para>
</sect2>
<sect2 id="other-tools">
<title>Accompanying tools</title>
<para>
A note on <command>makedepend</command>,
<command>autoheader</command>, <command>autoscan</command>,
<command>ifnames</command>, <command>aclocal</command>,
<command>autoproject</command>, <command>autoupdate</command>,
<command>autoreconf</command> etc.
</para>
</sect2>
</sect1>
<sect1 id="inside-look">
<title>An inside look</title>
<para>
To the survivors of the former section, this is an inside look at
the workings of all the GBS components. For starters, it describes
the innards of the &make; before covering a rather ill-known macro
programming language, <command>m4</command> upon which several of
the GBS tools are built. It then scrutinizes &autoconf;, &automake;
and &libtool; to answer <emphasis>what</emphasis> and
<emphasis>how</emphasis>.
</para>
<sect2 id="inside-make">
<title>Inside GNU &make;</title>
<para></para>
</sect2>
<sect2 id="inside-m4">
<title>The &m4; macro processor</title>
<para></para>
</sect2>
<sect2 id="inside-autoconf">
<title>Inside &autoconf;</title>
<para></para>
</sect2>
<sect2 id="inside-automake">
<title>Inside &automake;</title>
<para></para>
</sect2>
<sect2 id="inside-libtool">
<title>Inside &libtool;</title>
<para></para>
</sect2>
</sect1>
<sect1 id="tools-install">
<title>Installing the tools</title>
<para>
This section of the HOWTO covers the installation of the GBS
components, either from pre-packaged files specific to Linux
distributions, or from source <filename>.tar.gz</filename> (or
<filename>.tar.bz2</filename>) archives (also called
<emphasis>tarballs</emphasis>).
</para>
<sect2 id="distro-install">
<title>From distribution packages</title>
<para></para>
<sect3 id="fedora-install">
<title>Fedora</title>
<para></para>
</sect3>
<sect3 id="suse-install">
<title>SuSE</title>
<para></para>
</sect3>
<sect3 id="debian-install">
<title>Debian</title>
<para></para>
</sect3>
<sect3 id="mandrake-install">
<title>Mandrake</title>
<para></para>
</sect3>
</sect2>
<sect2 id="source-install">
<title>Installation from source</title>
<para></para>
</sect2>
</sect1>
<sect1 id="final-words">
<title>Final Words</title>
<!-- Translations -->
<sect2 id="translations">
<title>Translations</title>
<para></para>
<!--
<para>
Pointers to available translations are nice.
Also, your translators tend to give very important inputs.
</para>
<itemizedlist>
<listitem>
<para>
<ulink url="http://tldp.org/">French Translation</ulink>
provided by Individual <email>someone (at) somewhere.fr</email>
</para>
</listitem>
<listitem>
<para>
<ulink url="http://tldp.org/">German Translation</ulink>
provided by Individual <email>someone (at) somewhere.de</email>
</para>
</listitem>
</itemizedlist>
-->
</sect2>
<!-- Feedback -->
<sect2 id="feedback">
<title>Comments and Suggestions</title>
<para>
Comments and suggestions regarding this document may be sent to
<email>mark{dot}hoebeke{at}orange{dot}fr</email> and
<email>appaji@ibiblio.org</email>. Please point out
any mistakes, omissions, broken links and possible improvements so
that they can be incorporated in future revisions of the document.
In case you have additions and improvements that would change
major portions of the document, it would be great if you could
send them as a patch against the latest DocBook/XML version.
</para>
</sect2>
<!-- Give credit where credit is due...very important -->
<sect2 id="thanks">
<title>Acknowledgements</title>
<para>
The authors of this document have the pleasure of acknowledging
the following people who have contributed to this document by
sending in comments and suggestions for improvements.
<!-- Please scramble addresses; help prevent spam/email harvesting -->
<!--
<itemizedlist>
<listitem>
<para>Individual 1 <email>someone1 (at) somewhere.org</email></para>
</listitem>
<listitem>
<para>Individual 2 <email>someone2 (at) somewhere.org</email></para>
</listitem>
</itemizedlist>
-->
</para>
</sect2>
</sect1>
<sect1 id="resources">
<title>References and Resources</title>
<para>
No example is good enough to expose the hurdles that inevitably show
up when things get a bit more complex. The documents and references
provided as references can be used to further experiment with the
features that the tools described have to offer.
</para>
<itemizedlist>
<listitem>
<para>
<ulink
url="http://www.st-andrews.ac.uk/~iam/docs/tutorial.html">
Learning the GNU Development Tools</ulink> by Eleftherios
Gkioulekas is a good tutorial to understand the GNU build system
and the documentation files associated with GNU style packages.
</para>
</listitem>
<listitem>
<para>
The <quote>autotools</quote> referred to in the above tutorial
can be downloaded from <ulink
url="ftp://ftp.ugcs.caltech.edu/pub/elef/autotools">
ftp://ftp.ugcs.caltech.edu/pub/elef/autotools</ulink>. Though
the author seems to be planning a rewrite, it is worth taking a
look at.
</para>
</listitem>
<listitem>
<para>
<ulink
url="http://www.mv.com/ipusers/vanzandt/">autoproject:</ulink>
In the authors words, <quote>autoproject - a script to start a
programming project using &autoconf;, &automake;, and optionally
a command line parser generator</quote>
</para>
</listitem>
<listitem>
<para>
<ulink url="http://www.newriders.com/autoconf">GNU Autoconf,
Automake and Libtool</ulink> is probably the best guide for
mastering these tools. You can also read it online at <ulink
url="http://sources.redhat.com/autobook/download.html">
http://sources.redhat.com/autobook/download.html</ulink>
</para>
</listitem>
<listitem>
<para>
The official GNU &make; manual <ulink
url="&gnu;software/make/manual/index.html">
http://www.gnu.org/software/make/manual/index.html</ulink>. You
are encouraged to explore and write more complex rules, commands
in the rules, conditional parts, transformation of text in
&makefile;s etc., all of which are detailed in the manual.
</para>
</listitem>
<listitem>
<para>
The official &autoconf; manual <ulink
url="&gnu;software/autoconf/manual/autoconf-2.57/autoconf.html">
http://www.gnu.org/software/autoconf/manual/autoconf-2.57/autoconf.html</ulink>.
Take a look at the documentation of existing tests and learn how
to write new &autoconf; macros and tests. The indices of the
manual are great for reference.
</para>
</listitem>
<listitem>
<para>
Manuals of &automake; <ulink
url="&gnu;software/automake/manual/index.html">
http://www.gnu.org/software/automake/manual/index.html</ulink>.
A few examples, alternative approaches to handling
sub-directories, how various targets work, support for test
suites etc.
</para>
</listitem>
<listitem>
<para>
The official &libtool; manual <ulink
url="&gnu;software/libtool/manual.html">
http://www.gnu.org/software/libtool/manual.html</ulink>
</para>
</listitem>
<listitem>
<para>
Yet another language to pick up. The &m4; manual with lots of
examples is at <ulink url="&gnu;software/m4/manual/index.html">
http://www.gnu.org/software/m4/manual/index.html</ulink>
</para>
</listitem>
</itemizedlist>
</sect1>
<appendix id="gnu-gpl">
<appendixinfo>
<pubdate>Version 2, June 1991</pubdate>
<copyright>
<year>1989, 1991</year>
<holder>Free Software Foundation, Inc.</holder>
</copyright>
<legalnotice>
<para>
<address>
Free Software Foundation, Inc.
<street>59 Temple Place, Suite 330</street>,
<city>Boston</city>,
<state>MA</state>
<postcode>02111-1307</postcode>
<country>USA</country>
</address>.
</para>
<para>
Everyone is permitted to copy and distribute verbatim copies of
this license document, but changing it is not allowed.
</para>
</legalnotice>
<releaseinfo>Version 2, June 1991</releaseinfo>
</appendixinfo>
<title>GNU General Public License</title>
<titleabbrev>GNU-GPL</titleabbrev>
<sect1 id="gpl-preamble">
<title>Preamble</title>
<para>
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.
</para>
<para>
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.
</para>
<para>
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.
</para>
<para>
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.
</para>
<para>
We protect your rights with two steps:
<orderedlist>
<listitem>
<para>copyright the software, and </para>
</listitem>
<listitem>
<para>
offer you this license which gives you legal permission to
copy, distribute and/or modify the software.
</para>
</listitem>
</orderedlist>
</para>
<para>
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.
</para>
<para>
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.
</para>
<para>
The precise terms and conditions for copying, distribution and
modification follow.
</para>
</sect1>
<sect1 id="gpl-terms">
<title>TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND
MODIFICATION</title>
<sect2>
<title>Section 0</title>
<para>
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
<quote>work based on the Program </quote> 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 <quote>modification </quote>.) Each
licensee is addressed as <quote>you</quote>.
</para>
<para>
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.
</para>
</sect2>
<sect2 id="gpl-section1">
<title>Section 1</title>
<para>
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.
</para>
<para>
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.
</para>
</sect2>
<sect2 id="gpl-section2">
<title>Section 2</title>
<para>
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 <link
linkend="gpl-section1">Section 1 </link> above, provided that
you also meet all of these conditions:
<orderedlist>
<listitem>
<para>
You must cause the modified files to carry prominent
notices stating that you changed the files and the date of
any change.
</para>
</listitem>
<listitem>
<para>
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.
</para>
</listitem>
<listitem>
<para>
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.
<footnote>
<para>
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.
</para>
</footnote>
</para>
</listitem>
</orderedlist>
</para>
<para>
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.
</para>
<para>
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.
</para>
<para>
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.
</para>
</sect2>
<sect2 id="gpl-section3">
<title>Section 3</title>
<para>
You may copy and distribute the Program (or a work based on it,
under <link linkend="gpl-section2">Section 2 </link> in object
code or executable form under the terms of <link
linkend="gpl-section1">Sections 1 </link> and <link
linkend="gpl-section2">2 </link> above provided that you also do
one of the following:
<orderedlist>
<listitem>
<para>
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,
</para>
</listitem>
<listitem>
<para>
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,
</para>
</listitem>
<listitem>
<para>
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.)
</para>
</listitem>
</orderedlist>
</para>
<para>
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.
</para>
<para>
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.
</para>
</sect2>
<sect2 id="gpl-section4">
<title>Section 4</title>
<para>
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.
</para>
</sect2>
<sect2 id="gpl-section5">
<title>Section 5</title>
<para>
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.
</para>
</sect2>
<sect2 id="gpl-section6">
<title>Section 6</title>
<para>
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.
</para>
</sect2>
<sect2 id="gpl-section7">
<title>Section 7</title>
<para>
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.
</para>
<para>
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.
</para>
<para>
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.
</para>
<para>
This section is intended to make thoroughly clear what is
believed to be a consequence of the rest of this License.
</para>
</sect2>
<sect2 id="gpl-section8">
<title>Section 8</title>
<para>
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.
</para>
</sect2>
<sect2 id="gpl-section9">
<title>Section 9</title>
<para>
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.
</para>
<para>
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.
</para>
</sect2>
<sect2 id="gpl-section10">
<title>Section 10</title>
<para>
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.
</para>
</sect2>
<sect2 id="gpl-warranty">
<title>NO WARRANTY Section 11</title>
<para>
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.
</para>
</sect2>
<sect2 id="gpl-section12">
<title>Section 12</title>
<para>
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.
</para>
<para>END OF TERMS AND CONDITIONS</para>
</sect2>
</sect1>
<sect1 id="gpl-apply">
<title>How to Apply These Terms to Your New Programs</title>
<para>
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.
</para>
<para>
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.
</para>
<para>
&lt;one line to give the program's name and a brief idea of what
it does.&gt; Copyright &copy; &lt;year&gt; &lt;name of author&gt;
</para>
<para>
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.
</para>
<para>
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.
</para>
<para>
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
02111-1307 USA
</para>
<para>
Also add information on how to contact you by electronic and paper
mail.
</para>
<para>
If the program is interactive, make it output a short notice like
this when it starts in an interactive mode:
</para>
<para>
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.
</para>
<para>
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.
</para>
<para>
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:
</para>
<para>
Yoyodyne, Inc., hereby disclaims all copyright interest in the
program `Gnomovision' (which makes passes at compilers) written by
James Hacker.
</para>
<para>
&lt;signature of Ty Coon&gt;, 1 April 1989 Ty Coon, President of
Vice
</para>
<para>
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.
</para>
</sect1>
</appendix>
</article>
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