path: root/carbslinux.texi

\input texinfo    @c -*- texinfo -*-
@c %**start of header
@setfilename carbslinux.info
@settitle Carbs Linux User Manual
@documentencoding UTF-8
@documentlanguage en
@c %**end of header

@copying
Copyright @copyright{} 2020 Cem Keylan

@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts and no Back-Cover Texts.
A copy of the license is included in the section entitled "GNU Free
Documentation License."

@end quotation
@end copying

@dircategory System Administration
@direntry
* Carbs Linux: (carbslinux). Carbs Linux User Manual.
@end direntry

@finalout
@titlepage
@title Carbs Linux User Manual
@author Cem Keylan
@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage

@contents

@ifnottex
@node Top
@top Carbs Linux User Manual

This is the full documentation of @uref{https://carbslinux.org, Carbs Linux}, from the details of the
distribution, installation, to the package manager. It is not yet complete.

@ifplaintext
You can build and install the @command{info} package in order to view this
documentation with the info reader. It is divided into sections and easier to
read.
@end ifplaintext

@ifhtml
This documentation is also available in the distribution by the
@command{carbs-docs} package, which can be read by either running
@code{info carbslinux} or reading @file{/usr/share/doc/carbslinux.txt} with your
favorite pager. You can install either the @command{info} or @command{texinfo}
for doing the first.
@end ifhtml
@end ifnottex

@menu
* Installation::                 Installing Carbs Linux
* Init System::                  Configure the init system
* Contribution Guidelines::      Contribute to Carbs Linux
* GNU Free Documentation License:: Your rights

@detailmenu
--- The Detailed Node Listing ---

Installation

* Preparing Environment::        Getting ready to chroot
* Chroot::                       Going inside your new system
* System Configuration::         Customizing your system for personal use
* Kernel::                       Compiling your own kernel
* Making your system bootable::  Installing bootloader and boot scripts
* Post-installation::            Post-installation tasks

Preparing Environment

* Download::                     Download the root filesystem tarball
* Signature verification::       Verify the signature of the rootfs tarball
* Extracting the tarball::       Extracting the root filesystem to the desired location
* Obtain the chroot helper::     Download the script to easily chroot into the new filesystem

Chroot

* Setting up repositories::      Basic setup for obtaining repositories
* Updating packages::            Update your system
* Installing packages::          Install new software on your system
* Essential Software::           Software you might want to include on your system
* Obtaining the documentation::  Install documentation for offline use (optional)

System Configuration

* Configuring hostname::         Setting up system hostname (recommended)
* Hosts file::                   Setting up hosts file for networking (optional)

Kernel

* Obtaining the kernel sources:: Downloading the Linux source code
* Kernel dependencies::          Requirements for building the kernel
* Building the kernel::          Configure and compile the kernel

Making your system bootable

* Bootloader::                   Install a bootloader for your system
* Init scripts::                 Install init scripts for your system
* Fstab::                        Generating fstab

Post-installation

* KISS repositories::            Acquire kiss repositories

Init System

* Configuring Init::             Ways to configure the init system
* Changing Init Program::        Replace the default busybox init with something new

Configuring Init

* Kernel Command Line::          Configure init through the boot parameters
* @samp{/etc/init/rc.conf} file: @samp{/etc/init/rcconf} file.  Configure init through the configuration file
* Init Hooks::                   Configure init through hooks

Changing Init Program

* Rebooting after changing init:: Ways to reboot after replacing the init system

Contribution Guidelines

* Conventions::                  Conventions of the distribution

Conventions

* Shell Conventions::            Conventions for shell scripts
* Repository Conventions::       Conventions for repository build scripts

@end detailmenu
@end menu

@node Installation
@chapter Installation

These are the step-by-step instructions for installing Carbs Linux. It can be
acquired as plain-text to be viewed offline with a pager from
@uref{https://carbslinux.org/docs/install.txt}.

@menu
* Preparing Environment::        Getting ready to chroot
* Chroot::                       Going inside your new system
* System Configuration::         Customizing your system for personal use
* Kernel::                       Compiling your own kernel
* Making your system bootable::  Installing bootloader and boot scripts
* Post-installation::            Post-installation tasks
@end menu

@node Preparing Environment
@section Preparing Environment

To install Carbs Linux, you will need a Live Linux ISO@. For that purpose, you
can obtain a Gentoo or Void Linux live image. You can follow their instructions
to boot and setup your network.

You will need the following programs in order to install Carbs Linux:

@itemize
@item
tar
@item
wget
@item
xz
@item
some form of base utilities (coreutils, sbase, busybox, etc.)
@end itemize

Rest of these instructions will assume that you have set all of these up, and
will continue on that point.

@menu
* Download::                     Download the root filesystem tarball
* Signature verification::       Verify the signature of the rootfs tarball
* Extracting the tarball::       Extracting the root filesystem to the desired location
* Obtain the chroot helper::     Download the script to easily chroot into the new filesystem
@end menu

@node Download
@subsection Download

First, we need to download the rootfs tarball. You can do the following in order
to obtain the rootfs. If you are using an i686 machine, replace the @samp{x86_64}
with @samp{i686}. We are setting this in a URL variable so that we don't have to
write it every time.

@example
wget $URL/carbs-rootfs.tar.xz.sha256
sha256sum -c carbs-rootfs.tar.xz.sha256
@end example

@node Signature verification
@subsection Signature verification

It is highly recommended to verify the signature of the tarball. You will need
GPG for this.

@example
wget $URL/carbs-rootfs.tar.xz.sig
gpg --recv-keys FF484BDFEFCEF8FF
gpg --verify carbs-rootfs.tar.xz.sig
@end example

@node Extracting the tarball
@subsection Extracting the tarball

You will need to extract the tarball to your desired location. For partitioning,
you can follow @uref{https://wiki.archlinux.org/index.php/Partitioning, this guide}. This will assume that you will be mounting your root
partition to @samp{/mnt}.

@example
mount /dev/sdx1 /mnt
tar xf carbs-rootfs.tar.xz -C /mnt
@end example

@node Obtain the chroot helper
@subsection Obtain the chroot helper

You can obtain the @samp{cpt-chroot} script in order to do a simple chroot into your
new root filesystem.

@example
wget https://dl.carbslinux.org/distfiles/cpt-chroot
chmod a+x cpt-chroot
@end example

@node Chroot
@section Chroot

Chroot into Carbs Linux!

@example
./cpt-chroot /mnt
@end example

@menu
* Setting up repositories::      Basic setup for obtaining repositories
* Updating packages::            Update your system
* Installing packages::          Install new software on your system
* Essential Software::           Software you might want to include on your system
* Obtaining the documentation::  Install documentation for offline use (optional)
@end menu

@node Setting up repositories
@subsection Setting up repositories

Newest tarballs do not come with repositories, so you will need to manually
obtain them, and set your @samp{CPT_PATH} environment variable. Carbs Linux
repositories can either be obtained by @samp{git} or @samp{rsync}. While rsync
repositories are overall faster and smaller, git offers the whole history of the
repository and a means to manipulate your repository as you like it. If you want
to obtain the git repository, you will need to install @samp{git} itself.

The following guide will assume that you put the repositories into @samp{~/repos/}
directory, but you can put the repositories into any directory you want. So go
ahead and create that directory:

@example
mkdir -p $HOME/repos
@end example

@enumerate
@item
Obtaining from git


Carbs Linux git repositories can be found both from the main server and GitHub
(mirror). Here are both their repository links. You can clone any of them.

@itemize
@item
git://git.carbslinux.org/repository
@item
@uref{https://github.com/carbslinux/repository}
@end itemize

@example
git clone git://git.carbslinux.org/repository $HOME/repos/carbs
@end example

@item
Obtaining from rsync


Carbs Linux rsync repositories live in rsync://carbslinux.org/repo. In
order to obtain it, run the following:

@example
rsync -avc rsync://carbslinux.org/repo $HOME/repos/carbs
@end example

@item
Making the package manager use the repositories


In your shell's configuration file, or in your @samp{~/.profile} file, add the
following lines:

@example
CPT_PATH=$HOME/repos/carbs/core
CPT_PATH=$CPT_PATH:$HOME/repos/carbs/extra
CPT_PATH=$CPT_PATH:$HOME/repos/carbs/xorg
CPT_PATH=$CPT_PATH:$HOME/repos/carbs/community
export CPT_PATH
@end example
@end enumerate

@node Updating packages
@subsection Updating packages

It is good practice to make sure your system is up to date, especially before
building new packages. If there is an update for the package manager you will
need to update twice.

@example
cpt-update && cpt-update
@end example

@node Installing packages
@subsection Installing packages

Since you are operating on a really small base, you might need to build and
install new programs to extend the functionality of your system. In order to
build and install packages new packages in Carbs, you need to execute the
following. "Package" is not actually a package and is given as an example.

@example
cpt-build   package
cpt-install package
@end example

@node Essential Software
@subsection Essential Software

Here is a list of software that you might want to have on your system.

@strong{BOOTLOADERS}

@itemize
@item
efibootmgr
@item
grub
@end itemize

@strong{FILESYSTEMS}

@itemize
@item
e2fsprogs
@item
dosfstools
@item
ntfs-3g
@end itemize

@strong{NETWORKING}

@itemize
@item
dhcpcd
@item
wpa@math{_supplicant}
@end itemize

@strong{TEXT EDITORS}

@itemize
@item
nano
@item
vim
@item
neatvi
@item
emacs
@item
emacs-nox (terminal-only version of emacs)
@end itemize

@strong{USER SHELLS}

@itemize
@item
bash
@item
zsh
@item
oksh
@item
rc
@end itemize

@strong{POSIX BASE UTILITIES}

@itemize
@item
busybox
@item
sbase
@item
coreutils
@end itemize

@strong{DOCUMENTATION}

@itemize
@item
carbs-docs
@item
man-pages
@item
man-pages-posix
@end itemize

@node Obtaining the documentation
@subsection Obtaining the documentation

All the documentation for Carbs Linux can be found on a single info manual to be
viewed offline. You can obtain texinfo or the info (standalone) package in order
to view the documentation.

@example
# Install the documentation.
cpt b carbs-docs && cpt i carbs-docs

# Install either texinfo or the info package. We will be installing standalone info
# as it doesn't need perl.
cpt b info && cpt i info

# You can then run info and navigate through the documentation.
info carbslinux
@end example

@node System Configuration
@section System Configuration

After you have finished installing some extra packages, you can configure your
system to your liking.

@menu
* Configuring hostname::         Setting up system hostname (recommended)
* Hosts file::                   Setting up hosts file for networking (optional)
@end menu

@node Configuring hostname
@subsection Configuring hostname

You might want to add a hostname, especially in a networked environment. Your
hostname will default to 'carbslinux' unless you set this.

@example
echo your-hostname > /etc/hostname
@end example

@node Hosts file
@subsection Hosts file

You can edit your /etc/hosts file, which is the static lookup table for host
names. By default, there are two entries for localhost which are OKAY@. You can
replace the 'localhost' part of these entries to your hostname.

@example
127.0.0.1  localhost.localdomain localhost
::1        localhost.localdomain localhost ip6-localhost
@end example

@node Kernel
@section Kernel

Kernel isn't managed under the main repositories, even though you could package
one for your personal use. Here is an @uref{https://github.com/cemkeylan/kiss-repository/tree/master/personal/linux, example kernel package}, which you will
need to reconfigure for your specific setup if you want to make use of it.

@menu
* Obtaining the kernel sources:: Downloading the Linux source code
* Kernel dependencies::          Requirements for building the kernel
* Building the kernel::          Configure and compile the kernel
@end menu

@node Obtaining the kernel sources
@subsection Obtaining the kernel sources

You can visit the @uref{https://kernel.org} website to choose a kernel that you want
to install. Though only the latest stable and longterm (LTS) versions are
supported.

@example
# Download the kernel and extract it
wget https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.9.1.tar.xz
tar xf linux-5.9.1.tar.xz

# Change directory into the kernel sources
cd linux-5.9.1
@end example

@node Kernel dependencies
@subsection Kernel dependencies

In order to compile the kernel you will need to install some dependencies. You
will need @samp{libelf} to compile the kernel. If you want to configure using the
menu interface you will also need @samp{ncurses}.

@example
# The package manager asks to install if you are building more than one package,
# so no need to run 'cpt i ...'
cpt b libelf ncurses
@end example

In the vanilla kernel sources, you need perl to compile the kernel, but it can
be easily patched out. You will need to apply the following patch. Patch was
written by @uref{https://github.com/E5ten, E5ten}. You will need to obtain and apply the patch in the kernel
source directory.

@example
wget https://dl.carbslinux.org/distfiles/kernel-no-perl.patch
patch -p1 < kernel-no-perl.patch
@end example

@node Building the kernel
@subsection Building the kernel

Next step is configuring and building the kernel. You can check Gentoo's
@uref{https://wiki.gentoo.org/wiki/Kernel/Configuration, kernel configuration guide} to learn more about the matter. Overall, Gentoo Wiki
is a good place to learn about configuration according to your hardware. The
following will assume a monolithic kernel.

@example
make menuconfig
make
install -Dm755 $(make -s image_name) /boot/vmlinuz-linux
@end example

@node Making your system bootable
@section Making your system bootable

In order to be able to boot your fresh system, wou will need an init-daemon,
init-scripts and a bootloader. The init daemon is already provided by busybox,
but you can optionally change it.

@menu
* Bootloader::                   Install a bootloader for your system
* Init scripts::                 Install init scripts for your system
* Fstab::                        Generating fstab
@end menu

@node Bootloader
@subsection Bootloader

In the main repository, there is efibootmgr and grub to serve as bootloaders.
efibootmgr can be used as a standalone bootloader, or can be used to install
grub in a UEFI environment. efibootmgr is needed unless you are using a device
without UEFI support (or you really want to use BIOS for a reason).

@enumerate
@item
GRUB BIOS installation


@example
cpt b grub && cpt i grub
grub-install --target=i386-pc /dev/sdX
grub-mkconfig -o /boot/grub/grub.cfg
@end example

@item
GRUB UEFI installation


@example
cpt b efibootmgr && cpt i efibootmgr
cpt b grub && cpt i grub

grub-install --target=x86_64-efi \
             --efi-directory=esp \
             --bootloader-id=CarbsLinux

grub-mkconfig -o /boot/grub/grub.cfg
@end example
@end enumerate

@node Init scripts
@subsection Init scripts

Only thing left to do is installing the init-scripts, and now you are almost
ready to boot your system!

@example
cpt b carbs-init && cpt i carbs-init
@end example

@node Fstab
@subsection Fstab

You can now manually edit your fstab entry, or you can use the genfstab tool.
If you want to use the tool, exit the chroot and run the following:

@example
wget https://github.com/cemkeylan/genfstab/raw/master/genfstab
chmod +x genfstab
./genfstab -U /mnt >> /mnt/etc/fstab
@end example

@node Post-installation
@section Post-installation

The base installation is now complete, you can now fine tune your system
according to your needs. Rest of these instructions are completely optional.
You can check the rest of the documentation to learn more about the system.

@menu
* KISS repositories::            Acquire kiss repositories
@end menu

@node KISS repositories
@subsection KISS repositories

While not 100% compatible with cpt, you can use kiss repositories in your
system the same way you are using the distribution repositories. Here is an
example for the KISS Linux Community repository.

@node Init System
@chapter Init System

Carbs Linux init scripts are run by the init daemon (@samp{busybox} by default) on
boot and shutdown processes. It also provides its own halting program named
shalt. This provides a portable method that doesn't rely on non-POSIX external
programs.

@menu
* Configuring Init::             Ways to configure the init system
* Changing Init Program::        Replace the default busybox init with something new
@end menu

@node Configuring Init
@section Configuring Init

There are three ways you can change the behaviour of the init system. Those are:

@itemize
@item
Kernel Command Line
@item
@samp{/etc/init/rc.conf} file
@item
Init Hooks
@end itemize

@menu
* Kernel Command Line::          Configure init through the boot parameters
* @samp{/etc/init/rc.conf} file: @samp{/etc/init/rcconf} file.  Configure init through the configuration file
* Init Hooks::                   Configure init through hooks
@end menu

@node Kernel Command Line
@subsection Kernel Command Line

On GRUB, you can edit the kernel command line parameters, which will be parsed
as variables on the init system. Not all of the parameters will be acted upon,
but all of them will be set as variables on the init script. For example an
example command line, and how it is interpreted.

@example
BOOT_IMAGE=/boot/vmlinuz root=/dev/sda2 rw loglevel=3 quiet
@end example

This command line will be parsed to set the following variables:

@example
BOOT_IMAGE=/boot/vmlinuz
root=/dev/sda2
rw=1
loglevel=3
quiet=1
@end example

Some of these variables, such as @samp{rw=/=ro}, @samp{loglevel}, and @samp{quiet}, will be
used by the init system to change the behaviour of the startup.

@node @samp{/etc/init/rcconf} file
@subsection @samp{/etc/init/rc.conf} file

However, the kernel command line isn't the only place to set your boot
parameters. You can specify variables here as well, although note that the
kernel command line always gets the priority for these variables since they can
be set just before boot.

@node Init Hooks
@subsection Init Hooks

Init hooks are for custom personal commands that the user may want to add to
alter their boot. These can be used to load kernel modules, modify interfaces,
and lot more. Those hooks are added to the @samp{/etc/init} directory with the
hook name as the suffix. For example, a boot script will be placed as
@samp{/etc/init/my-hook.boot}. Currently, there are 4 hooks that the user can use.

@table @asis
@item early-boot
Run after pseudo-filesystems are mounted.
@item boot
Run before the boot stage is completed.
@item pre.shutdown
Run first when shutting down.
@item umount
Run just before filesystems are unmounted.
@item post.shutdown
Run just before the system is halted.
@end table

@node Changing Init Program
@section Changing Init Program

By default, Carbs Linux comes preinstalled with @samp{busybox-init}, but this can
easily be replaced without any issues. Currently, available init systems are:

@itemize
@item
@samp{sinit}
@item
@samp{busybox}
@item
@samp{runit}
@item
@samp{shinit}
@end itemize

This example is for runit, but it will work with all init systems packaged in the
distribution repositories. See the @samp{cpt-alternatives(1)} manual page for more
details.

@example
cpt a runit /usr/bin/init
cpt a runit /usr/bin/poweroff
cpt a runit /usr/bin/reboot
@end example

@menu
* Rebooting after changing init:: Ways to reboot after replacing the init system
@end menu

@node Rebooting after changing init
@subsection Rebooting after changing init

After switching init systems, your running init system may not accept the
new poweroff commands. You will need to reboot/poweroff using the running init's
utilities for the new utilities to work. These commands are for the init system
currently running on your system and not the one you are switching to.

@multitable {aaaaaaaaaaaa} {aaaaaaaaaaaaaaaa}
@headitem Program
@tab Command
@item busybox
@tab @samp{busybox reboot}
@item runit
@tab @samp{runit-init 6}
@item shinit/sinit
@tab @samp{kill -s INT 1}
@end multitable

@node Contribution Guidelines
@chapter Contribution Guidelines

Thanks for taking your time to contribute! To maintain stylistic behaviour
throughout the repositories, one must adhere to these conventions. Exceptions
and changes may occur with good reasoning.

@menu
* Conventions::                  Conventions of the distribution
@end menu

@node Conventions
@section Conventions

@macro contid{id}
[@anchor{\id\}\id\]
@end macro

@macro sectid{id, sect}
@strong{@contid{\id\} \sect\}
@end macro

@table @asis
@item [@anchor{0010}0010]
Try to keep the file readable.
@table @asis
@item [@anchor{0011}0011]
Characters on a line shouldn't exceed 100 characters.
@item [@anchor{0012}0012]
Make sure you don't have code commented out during
commit. Uncomment them or remove them completely.
@item [@anchor{0013}0013]
Do not add comments following the code, add them to the
top of the code. It makes it harder to read, and lines longer. Here is an example:
@end table

@example
# Good way of commenting.
your code goes here

your code goes here  # Avoid this way of commenting.
@end example
@end table

@menu
* Shell Conventions::            Conventions for shell scripts
* Repository Conventions::       Conventions for repository build scripts
@end menu

@node Shell Conventions
@subsection Shell Conventions

Shell is central to Carbs Linux projects. Most of the tools and packages are
written in POSIX sh.

@table @asis
@item [@anchor{1010}1010]
Use 4 spaces for indentation, don't use tabs.
@item [@anchor{1020}1020]
Make sure you don't use bash-specific code.
@item [@anchor{1030}1030]
Make sure you lint your code with @samp{shellcheck} and if
you are new to POSIX sh, use @samp{checkbashisms}.
@item [@anchor{1040}1040]
Don't spawn new processes if you don't absolutely need
to, especially during string manipulation.
@table @asis
@item [@anchor{1041}1041]
Never use a program for text manupilation that isn't
defined in the POSIX standard. This includes @samp{gawk} and @samp{perl}.
@item [@anchor{1042}1042]
Instead of @code{$(basename $file)}, use @code{$@{file##*@}}.
@item [@anchor{1043}1043]
Instead of @code{$(dirname $file)}, use @code{$@{file%/*@}}.
@end table

@example
# This is the same thing as basename /path/to/test.asc .asc

$ file=/path/to/test.asc file=$@{file##*/@} file=$@{file%.asc@}
$ echo $file
test
@end example
@item [@anchor{1050}1050]
Instead of backticks, use @code{$(..)}.
@end table

@node Repository Conventions
@subsection Repository Conventions

Repository conventions are important in order to ensure every package resemble
themselves. Here are the things to keep in mind:

@table @asis
@item [@anchor{2010}2010]
Prefer tarballs over git packages unless there is a
sensible reason. Here are some:
@itemize
@item
Every patch is a new release. (See @uref{https://github.com/vim/vim, vim})
@item
There are no releases. (See @uref{https://git.suckless.org/sbase, sbase})
@item
Following a development branch.
@item
There has been a long time since the latest release, but upstream is far
ahead.
@end itemize
@item [@anchor{2020}2020]
Prefer sources without a dependency to @samp{automake}. There
are usually distribution tarballs that are @samp{autoconf}'ed. Don't submit tarballs
with an automake dependency unless you are @samp{sure} there is no alternative.
@item [@anchor{2030}2030]
Avoid these packages:
@table @asis
@item dbus   
Usually can be disabled by @code{--disable-dbus}.
@item gettext
Usually can be disabled by @code{--disable-nls}.
@end table
@item [@anchor{2040}2040]
@itemize
@item
Always install a package to the @samp{/usr} prefix.
@item
All binaries should go to @samp{/usr/bin}, not @samp{/usr/sbin} or any other directory.
@item
All libraries should go to @samp{/usr/lib}.
@end itemize
@item [@anchor{2050}2050]
All build files on the repository should be a POSIX
shell script, and must start with @code{#!/bin/sh -e}.
@end table

The next section is about package templates that should be used in order to
ensure stylistic consistency. Note that the option configurations shouldn't be
taken literally, they are meant as examples.

@enumerate
@item
Make [@anchor{2210}2210]


@example
#!/bin/sh -e

make
make DESTDIR="$1" PREFIX=/usr install
@end example

@item
Configure/Make [@anchor{2211}2211]


@example
#!/bin/sh -e

./configure \
    --prefix=/usr \
    --disable-option \
    --enable-option

make
make DESTDIR="$1" install
@end example

@item
Autoconf/Automake [@anchor{2212}2212]


@xref{2020}

@example
#!/bin/sh -e

autoreconf -fi

./configure \
    --prefix=/usr \
    --disable-option \
    --enable-option

make
make DESTDIR="$1" install
@end example

@item
Meson [@anchor{2220}2220]


@example
#!/bin/sh -e

export DESTDIR=$1

meson \
    --prefix=/usr \
    -Doption=false \
    -Doption2=true \
    . output

ninja -C output
ninja -C output install
@end example

@item
Cmake [@anchor{2230}2230]


@example
#!/bin/sh -e

export DESTDIR=$1

cmake -B build \
    -DCMAKE_INSTALL_PREFIX=/usr \
    -DCMAKE_BUILD_TYPE=Release \
    -DOPTION=ON

cmake --build   build
cmake --install build
@end example

@item
Go [@anchor{2240}2240]


@example
#!/bin/sh -e

export GOPATH=$PWD/gopath
trap "go clean -modcache" EXIT INT
go mod vendor

go build
install -Dm755 program "$1/usr/bin/program"
@end example

@item
Python [@anchor{2241}2241]


@example
#!/bin/sh -e

python setup.py build
python setup.py install --prefix=/usr --root="$1"
@end example
@end enumerate

@node GNU Free Documentation License
@appendix GNU Free Documentation License

@center Version 1.3, 3 November 2008

@display
Copyright @copyright{} 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
@uref{http://fsf.org/}

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
@end display

@enumerate 0
@item
PREAMBLE

The purpose of this License is to make a manual, textbook, or other
functional and useful document @dfn{free}
in the sense of freedom: to assure everyone the effective freedom
to copy and redistribute it, with or without modifying it, either
commercially or noncommercially. Secondarily, this License
preserves for the author and publisher a way to get credit for
their work, while not being considered responsible for
modifications made by others.

This License is a kind of "copyleft", which means that derivative
works of the document must themselves be free in the same sense.
It complements the GNU General Public License, which is a copyleft
license designed for free software.

We have designed this License in order to use it for manuals for
free software, because free software needs free documentation:
a free program should come with manuals providing the same freedoms
that the software does.  But this License is not limited to
software manuals; it can be used for any textual work, regardless
of subject matter or whether it is published as a printed book.  We
recommend this License principally for works whose purpose is
instruction or reference.

@item
APPLICABILITY AND DEFINITIONS

This License applies to any manual or other work, in any medium,
that contains a notice placed by the copyright holder saying it can
be distributed under the terms of this License.  Such a notice
grants a world-wide, royalty-free license, unlimited in duration,
to use that work under the conditions stated herein.  The
"Document", below, refers to any such manual or work.  Any member
of the public is a licensee, and is addressed as "you".  You accept
the license if you copy, modify or distribute the work in a way
requiring permission under copyright law.

A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.

A "Secondary Section" is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document's overall
subject (or to related matters) and contains nothing that could
fall directly within that overall subject.  (Thus, if the Document
is in part a textbook of mathematics, a Secondary Section may not
explain any mathematics.)  The relationship could be a matter of
historical connection with the subject or with related matters, or
of legal, commercial, philosophical, ethical or political position
regarding them.

The "Invariant Sections" are certain Secondary Sections whose
titles are designated, as being those of Invariant Sections, in the
notice that says that the Document is released under this License.
If a section does not fit the above definition of Secondary then it
is not allowed to be designated as Invariant.  The Document may
contain zero Invariant Sections.  If the Document does not identify
any Invariant Sections then there are none.

The "Cover Texts" are certain short passages of text that are
listed, as Front-Cover Texts or Back-Cover Texts, in the notice
that says that the Document is released under this License.
A Front-Cover Text may be at most 5 words, and a Back-Cover Text
may be at most 25 words.

A "Transparent" copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images composed
of pixels) generic paint programs or (for drawings) some widely
available drawing editor, and that is suitable for input to text
formatters or for automatic translation to a variety of formats
suitable for input to text formatters.  A copy made in an otherwise
Transparent file format whose markup, or absence of markup, has
been arranged to thwart or discourage subsequent modification by
readers is not Transparent.  An image format is not Transparent if
used for any substantial amount of text.  A copy that is not
"Transparent" is called "Opaque".

Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, @LaTeX{} input format,
SGML or XML using a publicly available DTD, and standard-conforming
simple HTML, PostScript or PDF designed for human modification.
Examples of transparent image formats include PNG, XCF and JPG@.
Opaque formats include proprietary formats that can be read and
edited only by proprietary word processors, SGML or XML for which
the DTD and/or processing tools are not generally available, and
the machine-generated HTML, PostScript or PDF produced by some word
processors for output purposes only.

The "Title Page" means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the
material this License requires to appear in the title page.  For
works in formats which do not have any title page as such, "Title
Page" means the text near the most prominent appearance of the
work's title, preceding the beginning of the body of the text.

The "publisher" means any person or entity that distributes copies
of the Document to the public.

A section "Entitled XYZ" means a named subunit of the Document
whose title either is precisely XYZ or contains XYZ in parentheses
following text that translates XYZ in another language.  (Here XYZ
stands for a specific section name mentioned below, such as
"Acknowledgements", "Dedications", "Endorsements", or "History".)
To "Preserve the Title" of such a section when you modify the
Document means that it remains a section "Entitled XYZ" according
to this definition.

The Document may include Warranty Disclaimers next to the notice
which states that this License applies to the Document.  These
Warranty Disclaimers are considered to be included by reference in
this License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and
has no effect on the meaning of this License.

@item
VERBATIM COPYING

You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License
applies to the Document are reproduced in all copies, and that you
add no other conditions whatsoever to those of this License.  You
may not use technical measures to obstruct or control the reading
or further copying of the copies you make or distribute.  However,
you may accept compensation in exchange for copies.  If you
distribute a large enough number of copies you must also follow the
conditions in section 3.

You may also lend copies, under the same conditions stated above,
and you may publicly display copies.

@item
COPYING IN QUANTITY

If you publish printed copies (or copies in media that commonly
have printed covers) of the Document, numbering more than 100, and
the Document's license notice requires Cover Texts, you must
enclose the copies in covers that carry, clearly and legibly, all
these Cover Texts: Front-Cover Texts on the front cover, and
Back-Cover Texts on the back cover.  Both covers must also clearly
and legibly identify you as the publisher of these copies.  The
front cover must present the full title with all words of the title
equally prominent and visible.  You may add other material on the
covers in addition.  Copying with changes limited to the covers, as
long as they preserve the title of the Document and satisfy these
conditions, can be treated as verbatim copying in other respects.

If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto
adjacent pages.

If you publish or distribute Opaque copies of the Document
numbering more than 100, you must either include a machine-readable
Transparent copy along with each Opaque copy, or state in or with
each Opaque copy a computer-network location from which the general
network-using public has access to download using public-standard
network protocols a complete Transparent copy of the Document, free
of added material.  If you use the latter option, you must take
reasonably prudent steps, when you begin distribution of Opaque
copies in quantity, to ensure that this Transparent copy will
remain thus accessible at the stated location until at least one
year after the last time you distribute an Opaque copy (directly or
through your agents or retailers) of that edition to the public.

It is requested, but not required, that you contact the authors of
the Document well before redistributing any large number of copies,
to give them a chance to provide you with an updated version of the
Document.

@item
MODIFICATIONS

You may copy and distribute a Modified Version of the Document
under the conditions of sections 2 and 3 above, provided that you
release the Modified Version under precisely this License, with the
Modified Version filling the role of the Document, thus licensing
distribution and modification of the Modified Version to whoever
possesses a copy of it.  In addition, you must do these things in
the Modified Version:

@enumerate A
@item
Use in the Title Page (and on the covers, if any) a title
distinct from that of the Document, and from those of previous
versions (which should, if there were any, be listed in the
History section of the Document). You may use the same title as
a previous version if the original publisher of that version
gives permission.

@item
List on the Title Page, as authors, one or more persons or
entities responsible for authorship of the modifications in the
Modified Version, together with at least five of the principal
authors of the Document (all of its principal authors, if it has
fewer than five), unless they release you from this requirement.

@item
State on the Title page the name of the publisher of the
Modified Version, as the publisher.

@item
Preserve all the copyright notices of the Document.

@item
Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.

@item
Include, immediately after the copyright notices, a license
notice giving the public permission to use the Modified Version
under the terms of this License, in the form shown in the
Addendum below.

@item
Preserve in that license notice the full lists of Invariant
Sections and required Cover Texts given in the Document's
license notice.

@item
Include an unaltered copy of this License.

@item
Preserve the section Entitled "History", Preserve its Title, and
add to it an item stating at least the title, year, new authors,
and publisher of the Modified Version as given on the Title
Page. If there is no section Entitled "History" in the Document,
create one stating the title, year, authors, and publisher of
the Document as given on its Title Page, then add an item
describing the Modified Version as stated in the previous
sentence.

@item
Preserve the network location, if any, given in the Document
for public access to a Transparent copy of the Document, and
likewise the network locations given in the Document for
previous versions it was based on. These may be placed in the
"History" section. You may omit a network location for a work
that was published at least four years before the Document
itself, or if the original publisher of the version it refers
to gives permission.

@item
For any section Entitled "Acknowledgements" or "Dedications",
Preserve the Title of the section, and preserve in the section
all the substance and tone of each of the contributor
acknowledgements and/or dedications given therein.

@item
Preserve all the Invariant Sections of the Document, unaltered
in their text and in their titles. Section numbers or the
equivalent are not considered part of the section titles.

@item
Delete any section Entitled "Endorsements". Such a section may
not be included in the Modified Version.

@item
Do not retitle any existing section to be Entitled
"Endorsements" or to conflict in title with any Invariant
Section.

@item
Preserve any Warranty Disclaimers.
@end enumerate

If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no material
copied from the Document, you may at your option designate some or all
of these sections as invariant.  To do this, add their titles to the
list of Invariant Sections in the Modified Version's license notice.
These titles must be distinct from any other section titles.

You may add a section Entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
parties---for example, statements of peer review or that the text has
been approved by an organization as the authoritative definition of a
standard.

You may add a passage of up to five words as a Front-Cover Text, and a
passage of up to 25 words as a Back-Cover Text, to the end of the list
of Cover Texts in the Modified Version.  Only one passage of
Front-Cover Text and one of Back-Cover Text may be added by (or
through arrangements made by) any one entity.  If the Document already
includes a cover text for the same cover, previously added by you or
by arrangement made by the same entity you are acting on behalf of,
you may not add another; but you may replace the old one, on explicit
permission from the previous publisher that added the old one.

The author(s) and publisher(s) of the Document do not by this License
give permission to use their names for publicity for or to assert or
imply endorsement of any Modified Version.

@item
COMBINING DOCUMENTS

You may combine the Document with other documents released under
this License, under the terms defined in section 4 above for
modified versions, provided that you include in the combination all
of the Invariant Sections of all of the original documents,
unmodified, and list them all as Invariant Sections of your
combined work in its license notice, and that you preserve all
their Warranty Disclaimers.

The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy.  If there are multiple Invariant Sections with the same name
but different contents, make the title of each such section unique
by adding at the end of it, in parentheses, the name of the
original author or publisher of that section if known, or else
a unique number.  Make the same adjustment to the section titles in
the list of Invariant Sections in the license notice of the
combined work.

In the combination, you must combine any sections Entitled
"History" in the various original documents, forming one section
Entitled "History"; likewise combine any sections Entitled
"Acknowledgements", and any sections Entitled "Dedications".  You
must delete all sections Entitled "Endorsements."

@item
COLLECTIONS OF DOCUMENTS

You may make a collection consisting of the Document and other
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy
that is included in the collection, provided that you follow the
rules of this License for verbatim copying of each of the documents
in all other respects.

You may extract a single document from such a collection, and
distribute it individually under this License, provided you insert
a copy of this License into the extracted document, and follow this
License in all other respects regarding verbatim copying of that
document.

@item
AGGREGATION WITH INDEPENDENT WORKS

A compilation of the Document or its derivatives with other
separate and independent documents or works, in or on a volume of
a storage or distribution medium, is called an "aggregate" if the
copyright resulting from the compilation is not used to limit the
legal rights of the compilation's users beyond what the individual
works permit.  When the Document is included in an aggregate, this
License does not apply to the other works in the aggregate which
are not themselves derivative works of the Document.

If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half
of the entire aggregate, the Document's Cover Texts may be placed
on covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic
form.  Otherwise they must appear on printed covers that bracket
the whole aggregate.

@item
TRANSLATION

Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of
section 4.  Replacing Invariant Sections with translations requires
special permission from their copyright holders, but you may
include translations of some or all Invariant Sections in addition
to the original versions of these Invariant Sections.  You may
include a translation of this License, and all the license notices
in the Document, and any Warranty Disclaimers, provided that you
also include the original English version of this License and the
original versions of those notices and disclaimers.  In case of
a disagreement between the translation and the original version of
this License or a notice or disclaimer, the original version will
prevail.

If a section in the Document is Entitled "Acknowledgements",
"Dedications", or "History", the requirement (section 4) to
Preserve its Title (section 1) will typically require changing the
actual title.

@item
TERMINATION

You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense, or distribute it is void,
and will automatically terminate your rights under this License.

However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
provisionally, unless and until the copyright holder explicitly and
finally terminates your license, and (b) permanently, if the
copyright holder fails to notify you of the violation by some
reasonable means prior to 60 days after the cessation.

Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from
that copyright holder, and you cure the violation prior to 30 days
after your receipt of the notice.

Termination of your rights under this section does not terminate
the licenses of parties who have received copies or rights from you
under this License.  If your rights have been terminated and not
permanently reinstated, receipt of a copy of some or all of the
same material does not give you any rights to use it.

@item
FUTURE REVISIONS OF THIS LICENSE

The Free Software Foundation may publish new, revised versions of
the GNU Free Documentation 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.  See
@uref{http://www.gnu.org/copyleft/}.

Each version of the License is given a distinguishing version
number.  If the Document specifies that a particular numbered
version of this License "or any later version" applies to it, you
have the option of following the terms and conditions either of
that specified version or of any later version that has been
published (not as a draft) by the Free Software Foundation.  If
the Document does not specify a version number of this License,
you may choose any version ever published (not as a draft) by the
Free Software Foundation.  If the Document specifies that a proxy
can decide which future versions of this License can be used, that
proxy's public statement of acceptance of a version permanently
authorizes you to choose that version for the Document.

@item
RELICENSING

"Massive Multiauthor Collaboration Site" (or "MMC Site") means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works.
A public wiki that anybody can edit is an example of such
a server.  A "Massive Multiauthor Collaboration" (or "MMC")
contained in the site means any set of copyrightable works thus
published on the MMC site.

"CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation,
a not-for-profit corporation with a principal place of business in
San Francisco, California, as well as future copyleft versions of
that license published by that same organization.

"Incorporate" means to publish or republish a Document, in whole
or in part, as part of another Document.

An MMC is "eligible for relicensing" if it is licensed under this
License, and if all works that were first published under this
License somewhere other than this MMC, and subsequently
incorporated in whole or in part into the MMC, (1) had no cover
texts or invariant sections, and (2) were thus incorporated prior
to November 1, 2008.

The operator of an MMC Site may republish an MMC contained in the
site under CC-BY-SA on the same site at any time before August 1,
2009, provided the MMC is eligible for relicensing.
@end enumerate

@page

@anchor{ADDENDUM How to use this License for your documents}
@appendixsec ADDENDUM: How to use this License for your documents

To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and
license notices just after the title page:

@example
Copyright (C)  YEAR  YOUR NAME.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts.  A copy of the license is included in the section entitled ``GNU
Free Documentation License''.
@end example

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the "with@dots{}Texts."@tie{}line with this:

@example
with the Invariant Sections being LIST THEIR TITLES, with
the Front-Cover Texts being LIST, and with the Back-Cover Texts
being LIST.
@end example

If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.

If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License, to
permit their use in free software.

@bye