.. todo::

 * /etc/motd

Choices
=======

have up-to-date mirrors available
---------------------------------

.. todo:: sync mirrors
.. todo:: check mirrors

critical base packages
----------------------

 +-----------+--------------------------------------------------+
 | locales   | to get localization binaries for system messages |
 +-----------+--------------------------------------------------+
 | apt-utils | otherwise packages configuration gets delayed    |
 +-----------+--------------------------------------------------+
 | dialog    | to have user interaction possible with APT       |
 +-----------+--------------------------------------------------+

decide the desired type of system
---------------------------------

* will the system run
  * 64 bits?
  * 32 bits?
  * both?
* will the system be run by
  * a physical machine?
  * a virtual machine?
  * a container?
  * a container inside a virtual machine?
* will the system be stored
  * read-write, as a file system on a dedicated partition?
  * read-only, as a single file loaded in RAM at boot time?

Install required tools
======================

 ============== ========================================
 debootstrap    generate a minimal base file system
 squashfs-tools archive or unarchive a file system image
 ============== ========================================

 .. code:: shell

  apt install debootstrap squashfs-tools

Create a base file hierarchy
============================

prepare the system's directory
------------------------------

* become root
* make root directory

.. code:: shell

 su

.. code:: shell

 mkdir '/squashfs-root'

generate the minimal base
-------------------------

.. code:: shell

 debootstrap \
 --arch 'amd64' \
 --variant 'minbase' \
 --include 'locales,apt-utils,dialog' \
 'bullseye' \
 '/squashfs-root' \
 'https://deb.debian.org/debian'

Configure preinstalled packages
===============================

define default locale
---------------------

* etc/default/locale

::

 LANG='en_US.UTF-8'
 LANGUAGE='en_US:en'
 LC_CTYPE='fr_FR.UTF-8'
 LC_NUMERIC='fr_FR.UTF-8'
 LC_TIME='fr_FR.UTF-8'
 LC_COLLATE='fr_FR.UTF-8'
 LC_MONETARY='fr_FR.UTF-8'
 LC_MESSAGES='en_US.UTF-8'
 LC_PAPER='fr_FR.UTF-8'
 LC_NAME='fr_FR.UTF-8'
 LC_ADDRESS='fr_FR.UTF-8'
 LC_TELEPHONE='fr_FR.UTF-8'
 LC_MEASUREMENT='fr_FR.UTF-8'
 LC_IDENTIFICATION='fr_FR.UTF-8'

define locales to generate
--------------------------

* etc/locale.gen

::

 en_US.UTF-8 UTF-8
 fr_FR.UTF-8 UTF-8

generate locales
----------------

.. code:: shell

 locale-gen

define default keyboard layouts
-------------------------------

* /etc/default/keyboard

::

 XKBMODEL="pc105"
 XKBLAYOUT="fr,fr"
 XKBVARIANT="oss,bepo"
 XKBOPTIONS=""
 BACKSPACE="guess"

[configure command shell](../bash/index.md)
-------------------------------------------

[configure package manager](../apt/index.md)
--------------------------------------------

redefine hostname
-----------------

.. code:: shell

 echo "hostname" > "etc/hostname"

provide known file systems
--------------------------

* etc/fstab

Volume temporaire en RAM

::

 tmpfs /tmp tmpfs auto,mode=1777 0 0

Install additional packages
===========================

switch into context
-------------------

.. code:: shell

 for f in 'dev' 'dev/pts' 'proc' 'sys' ; do
     mount --bind "/${f}" "/squashfs-root/${f}"
 done
 chroot '/squashfs-root'

.. todo:: /dev

define root password
--------------------

.. code:: shell

 passwd

user, guest, sudo
-----------------

.. code:: shell

 apt-get install sudo

 useradd -s /bin/bash user
 mkdir /home/user
 chown user: /home/user
 adduser user sudo

 useradd -s /bin/bash guest
 chown guest: /home/guest

authentications: passwords, SSH keys
------------------------------------

.. todo:: files

upgrade system
--------------

* dans tous les cas :

.. code:: shell

 apt-get update
 apt-get upgrade

* si besoin, car des paquets rétroportés modifient la distribution :

.. code:: shell

 apt-get dist-upgrade

apply system type elements
--------------------------

================= ==================================================
linux-image-amd64 s’il ne s’agit pas d’un conteneur
live-boot         si à destination de boot live
systemd-sysv      sans quoi le système ne démarrera pas complètement
================= ==================================================

.. code:: shell

 apt-get install -t stretch-backports 'linux-image-amd64'
 apt-get install 'live-boot'

----

initialization settings
-----------------------

.. code:: shell

 apt-get install -t stretch-backports "systemd-sysv"

* etc/sysctl.conf

Espace mémoire maximum allouable (à augmenter si hébergement de conteneurs)  
Pourcentage de RAM disponible avant utilisation de la partition d’échange  

.. code:: ini

 vm.max_map_count=1048576
 vm.swappiness=0

keeping things light
--------------------

.. code:: shell

 apt-get install --no-install-recommends …

install useful packages
-----------------------

.. code:: shell

 apt-get install \
 bash-completion \
 lxc \
 less nano vim \
 pciutils usbutils \
 python3 \
 squashfs-tools

.. code:: shell

 apt-get install \
 --target-release 'bullseye-backports' \
 debootstrap

install other packages
----------------------

[Choix de paquets commentés](packages.md)

.. code:: shell

 apt-get install "package1" …
 apt-get install -t stretch-backports "package1" …

properly switch back from context
---------------------------------

* empty APT's cache

.. code:: shell

 apt-get clean

* exit the environment

.. code:: shell

 exit

* untie links to host system

.. code:: shell

 for f in 'sys' 'proc' 'dev/pts' 'dev' ; do
     umount --lazy "/squashfs-root/${f}"
 done

clean up commands history
-------------------------

* root/.bash_history

Configure installed packages
============================

.. todo:: files

Archive prepared file system
============================

.. code:: shell

 mksquashfs \
 '/squashfs-root' \
 'filesystem.squashfs' \
 -b '1m' \
 -comp 'zstd' \
 -Xcompression-level 22