Installation
To use Debian, you need to install it on a computer; this task is taken care of by the debian-installer program. A proper installation involves many operations. This chapter reviews them in their chronological order.
installation
of the system
The installer for Bookworm is based on debian-installer. Its modular design enables it to work in various scenarios and allows it to evolve and adapt to changes. Despite the limitations implied by the need to support a large number of architectures, this installer is very accessible to beginners, since it assists users at each stage of the process. Automatic hardware detection, guided partitioning, and graphical user interfaces have solved most of the problems that novices used to face in the early years of Debian.
installer
debian-installer
Installation requires 256 MB of RAM (Random Access Memory) and at least 2 GB of hard drive space. All Falcot computers meet these criteria. Note, however, that these figures apply to the installation of a very limited system without a graphical desktop. A minimum of 2 GB of RAM and 10 GB of hard drive space are really recommended for a basic office desktop workstation.
Installation Methods
A Debian system can be installed from several types of media, as long as the BIOS/UEFI (see ???) of the machine allows it. You can for instance boot with a CD-ROM, a USB key, or even through a network.
Installing from a CD-ROM/DVD-ROM
installation
from a CD-ROM/DVD-ROM
The most widely used installation method is from a CD-ROM (or DVD-ROM, which behaves exactly the same way): the computer is booted from this media, and the installation program takes over.
netinst.iso
installation
netinst
Various CD-ROM families have different purposes: netinst (network installation) contains the installer and the base Debian system; all other programs are then downloaded. Its “image”, that is the ISO-9660 filesystem that contains the exact contents of the disk, takes up about 310 to 780 MB (depending on the architecture). On the other hand, the complete set offers all packages and allows for installation on a computer that has no Internet access; it requires around 21 DVD-ROMs (or 5 Blu-ray disks). There is no more official CD-ROMs set as they were really huge, rarely used and now most of the computers use DVD-ROMs as well as CD-ROMs. But the programs are divided among the disks according to their popularity and importance; the first disk will be sufficient for most installations, since it contains the most used software.
There is a last type of image, known as mini.iso, which is only available as a by-product of the installer. The image only contains the minimum required to configure the network and everything else is downloaded (including parts of the installer itself, which is why those images tend to break when a new version of the installer is released). Those images are usually smaller than 100MB, and they can be found on the normal Debian mirrors under the dists/release/main/installer-arch/current/images/netboot/ directory.
mini.iso
CD-ROM
installation CD-ROM
CD-ROM
netinst CD-ROM
DVD-ROM
installation DVD-ROM
DVD-ROM
netinst DVD-ROM
To acquire Debian CD-ROM images, you may, of course, download them and burn them to disk. You may also purchase them, and, thus, provide the project with a little financial support. Check the website to see the list of DVD-ROM image vendors and download sites.
Booting from a USB Key
USB key
installation
from a USB key
Since most computers are able to boot from USB devices, you can also install Debian from a USB key (this is nothing more than a small flash-memory disk).
The installation manual explains how to create a USB key that contains the debian-installer. The procedure is very simple because ISO images for i386 and amd64 are hybrid images that can boot from a CD-ROM as well as from a USB key.
You must first identify the device name of the USB key (ex: /dev/sdb); the simplest means to do this is to check the messages issued by the kernel using the dmesg command. Then you must copy the previously downloaded ISO image (for example, debian-12.0.0-amd64-netinst.iso) with the command cat debian-12.0.0-amd64-netinst.iso >/dev/sdb; sync. This command requires administrator rights, since it accesses the USB key directly and blindly erases its content.
A more detailed explanation is available in the installation manual. Among other things, it describes an alternative method of preparing a USB key that is more complex, but that allows you to customize the installer's default options (those set in the kernel command line).
Installing through Network Booting
installation
netboot installation
installation
PXE installation
installation
TFTP installation
PXE
TFTP
Trivial File Transfer Protocol
Trivial File Transfer Protocol
Many BIOSes allow booting directly from the network by downloading a kernel and a minimal filesystem image. This method (which has several names, such as PXE or TFTP boot) can be a life-saver if the computer does not have a CD-ROM reader, or if the BIOS can't boot from such media.
This installation method works in two steps. First, while booting the computer, the BIOS (or the network card) issues a BOOTP/DHCP request to automatically acquire an IP address. When a BOOTP or DHCP server returns a response, it includes a filename, as well as network settings. After having configured the network, the client computer then issues a TFTP (Trivial File Transfer Protocol) request for a file whose name was previously indicated. Once this file is acquired, it is executed as though it were a bootloader. This then launches the Debian installation program, which is executed as though it were running from the hard drive, a CD-ROM, or a USB key.
All the details of this method are available in the installation guide (“Preparing files for TFTP Net Booting” section).
Other Installation Methods
installation
custom installation
When we have to deploy customized installations for a large number of computers, we generally choose an automated rather than a manual installation method. Depending on the situation and the complexity of the installations to be made, we can use FAI (Fully Automatic Installer, described in ???), or even a customized installation DVD with so-called “preseeding“ (see ???).
installation
remote installation
It should also be noted that the installer can load and run an SSH server and thus provides the ability to install Debian remotely via an SSH session. The release notes also describe how to run the installer from an existing system using grub to replace it completely.
Installing, Step by Step
Booting and Starting the Installer
Once the BIOS has begun booting from the CD- or DVD-ROM, the Isolinux bootloader menu appears. At this stage, the Linux kernel is not yet loaded; this menu allows you to choose the kernel to boot and enter possible parameters to be transferred to it in the process.
For a standard installation, you only need to choose “Install” or “Graphical install” (with the arrow keys), then press the Enter key to initiate the remainder of the installation process. If the DVD-ROM is a “Multi-arch” disk, and the machine has an Intel or AMD 64-bit processor, those menu options enable the installation of the 64-bit variant (amd64) and the installation of the 32-bit variant remains available in a dedicated sub-menu (“32-bit install options”). If you have a 32-bit processor, you don't get a choice and the menu entries install the 32-bit variant (i386).
The “expert” mode (accessible in the “Advanced options” menu) details all possible options in the process of installation, and allows navigation between the various steps without them happening automatically in sequence. Be careful, this very verbose mode can be confusing due to the multitude of configuration choices that it offers.
The “rescue” mode, also accessible in the “Advanced options” menu, allows recovering a broken system or fixing the bootloader. After presenting the first few screens of the installer, it will allow you to enter a shell prompt in the file system you selected to perform any necessary actions, or to re-install the bootloader.
Once booted, the installation program guides you step by step throughout the process. This section presents each of these steps in detail. Here we follow the process of an installation from an amd64 DVD-ROM (more specifically, the version 12.5.0 of the installer for Bookworm); netinst installations, as well as later releases of the installer, may look slightly different. We will also address installation in graphical mode, but the only difference from “classic” (text-mode) installation is in the visual appearance.
Selecting the language
choice
of language
The installation program begins in English, but the first step allows the user to choose the language that will be used in the rest of the process. Choosing French, for example, will provide an installation entirely translated into French (and a system configured in French as a result). This choice is also used to define more relevant default choices in subsequent stages (notably the keyboard layout).
Selecting the country
choice
of country
The second step consists in choosing your country. Combined with the language, this information enables the program to offer the most appropriate keyboard layout. This will also influence the configuration of the time zone. In the United States, a standard QWERTY keyboard is suggested, and a choice of appropriate time zones is offered.
Selecting the keyboard layout
keyboard layout
layout, keyboard
choice
of keyboard layout
The proposed “American English” keyboard corresponds to the usual QWERTY layout.
Detecting Hardware
detecting
hardware
This step is completely automatic in the vast majority of cases. The installer detects your hardware, and tries to identify the CD-ROM drive used in order to access its content. It loads the modules corresponding to the various hardware components detected, and then “mounts” the CD-ROM in order to read it. The previous steps were completely contained in the boot image included on the CD, a file of limited size and loaded into memory by the BIOS when booting from the CD.
The installer can work with the vast majority of drives, especially standard ATAPI (sometimes called IDE and EIDE) and SCSI peripherals. However, if detection of the CD-ROM reader fails, the installer offers the choice to load a kernel module (for instance, from a USB key) corresponding to the CD-ROM driver.
Loading Components
With the contents of the CD now available, the installer loads all the files necessary to continue with its work. This includes additional drivers for the remaining hardware (especially the network card), as well as all the components of the installation program.
Detecting Network Hardware
detecting
network hardware
This automatic step tries identifying the network card and loads the corresponding module. If automatic detection fails, you can manually select the module to load. If no module works, it is possible to load a specific module from a removable device. This last solution is usually only needed if the appropriate driver is not included in the standard Linux kernel, but available elsewhere, such as the manufacturer's website or in firmware archives/packages.
This step must absolutely be successful for netinst installations, since the Debian packages must be loaded from the network.
Configuring the Network
configuration
network
static
configuration
network
DHCP
In order to automate the process as much as possible, the installer attempts an automatic network configuration by DHCP (for IPv4) and by IPv6 network discovery. If this fails, it offers more choices: try again with a normal DHCP configuration, attempt DHCP configuration by declaring the name of the machine, or set up a static network configuration.
This last option requires an IP address, a subnet mask, an IP address for a potential gateway, a machine name, and a domain name.
Administrator Password
account
administrator account
account
root account
administrator
root
super-user
root
root
The super-user root account, reserved for the machine's administrator, is automatically created during installation; this is why a password is requested. The installer also asks for a confirmation of the password to prevent any input error, which would later be difficult to amend. Note that you can leave both fields empty if you want the root account to be disabled. In that case, the login for the root user will be deactivated and the first regular user — that will be created by the installer in the next step — will have administrative rights through sudo (see ???).
Creating the First User
Debian also imposes the creation of a standard user account so that the administrator doesn't get into the bad habit of working as root. The precautionary principle essentially means that each task is performed with the minimum required rights, in order to limit the damage caused by human error. This is why the installer will ask for the complete name of this first user, their username, and their password (twice, to prevent the risk of erroneous input).
Configuring the Clock
If the network is available, the system's internal clock is updated (in a one-shot way) from an NTP server. This way the timestamps on logs will be correct from the first boot. For them to remain consistently precise over time, an NTP daemon needs to be set up after initial installation (see ???).
Detecting Disks and Other Devices
detecting
disks
This step automatically detects the hard drives on which Debian may be installed. They will be presented in the next step: partitioning.
Starting the Partitioning Tool
partitioning
The partitioning step is traditionally difficult for new users. It is necessary to define the various portions of the disks (or “partitions”) on which the Linux filesystems and virtual memory (swap) will be stored. This task is complicated if another operating system that you want to keep is already on the machine. Indeed, you will then have to make sure that you do not alter its partitions (or that you resize them without causing damage).
Fortunately, the partitioning software has a “guided” mode which recommends partitions for the user to make — in most cases, you can simply validate the software's suggestions.
The first screen in the partitioning tool offers the choice of using an entire hard drive to create various partitions. For a (new) computer which will solely use Linux, this option is clearly the simplest, and you can choose the option “Guided - use entire disk”. If the computer has two hard drives for two operating systems, setting one drive for each is also a solution that can facilitate partitioning. In both of these cases, the next screen offers to choose the disk where Linux will be installed by selecting the corresponding entry (for example, “SCSI1 (0,0,0) (sda) - 53.7 GB ATA QEMU HARDDISK”). You then start guided partitioning.
Guided partitioning can also set up LVM logical volumes instead of partitions (see below). Since the remainder of the operation is the same, we will not go over the option “Guided - use entire disk and set up LVM” (encrypted or not).
In other cases, when Linux must work alongside other already existing partitions, you need to choose manual partitioning.
Guided partitioning
partitioning
guided partitioning
The guided partitioning tool offers three partitioning methods, which correspond to different usages.
The first method is called “All files in one partition”. The entire Linux system tree is stored in a single filesystem, corresponding to the root / directory. This simple and robust partitioning fits perfectly for personal or single-user systems. In fact, two partitions will be created: the first will house the complete system, the second the virtual memory (swap).
The second method, “Separate /home partition”, is similar, but splits the file hierarchy in two: one partition contains the Linux system (/), and the second contains “home directories” (meaning user data, in files and subdirectories available under /home/).
The last partitioning method, called “Separate /home, /var, and /tmp partitions”, is appropriate for servers and multi-user systems. It divides the file tree into many partitions: in addition to the root (/) and user accounts (/home/) partitions, it also has partitions for server software data (/var/), and temporary files (/tmp/). These divisions have several advantages. Users can not lock up the server by consuming all available hard drive space (they can only fill up /tmp/ and /home/). The daemon data (especially logs) can no longer clog up the rest of the system.
After choosing the type of partition, the software calculates a suggestion, and describes it on the screen; the user can then modify it if needed. You can, in particular, choose another filesystem if the standard choice (ext4) isn't appropriate. In most cases, however, the proposed partitioning is reasonable and it can be accepted by selecting the “Finish partitioning and write changes to disk” entry.
Manual Partitioning
partitioning
manual partitioning
Manual partitioning allows greater flexibility, allowing the user to choose the purpose and size of each partition. Furthermore, this mode is unavoidable if you wish to use software RAID.
The first screen displays the available disks, their partitions, and any possible free space that has not yet been partitioned. You can select each displayed element; pressing the Enter key then gives a list of possible actions.
You can erase all partitions on a disk by selecting it.
When selecting free space on a disk, you can manually create a new partition. You can also do this with guided partitioning, which is an interesting solution for a disk that already contains another operating system, but which you may wish to partition for Linux in a standard manner. See Guided partitioning for more details on guided partitioning.
When choosing a partition, you can indicate the manner in which you are going to use it:
-
format it and include it in the file tree by choosing a mount point;
-
use it as a swap partition;
-
make it into a “physical volume for encryption” (to protect the confidentiality of data on certain partitions, see below);
-
make it a “physical volume for LVM” (this concept is discussed in greater detail later in this chapter);
-
use it as a RAID device (see later in this chapter);
-
you can also choose not to use it, and therefore leave it unchanged.
Configuring Multidisk Devices (Software RAID)
RAID
Software RAID
Software RAID
device
multi-disk device
Some types of RAID allow the duplication of information stored on hard drives to prevent data loss in the event of a hardware problem affecting one of them. Level 1 RAID keeps a simple, identical copy (mirror) of a hard drive on another drive, while level 5 or 6 RAID splits redundant data over several disks, thus allowing the complete reconstruction of a failing drive.
We will only describe level 1 RAID, which is the simplest to implement. The first step involves creating two partitions of identical size located on two different hard drives, and to label them “physical volume for RAID”.
You must then choose “Configure software RAID” in the partitioning tool to combine these two partitions into a new virtual disk and select “Create MD device” in the configuration screen. You then need to answer a series of questions about this new device. The first question asks about the RAID level to use, which in our case will be “RAID1”. The second question asks about the number of active devices — two in our case, which is the number of partitions that need to be included in this MD device. The third question is about the number of spare devices — 0; we have not planned any additional disk to take over for a possible defective disk. The last question requires you to choose the partitions for the RAID device — these would be the two that we have set aside for this purpose (make sure you only select the partitions that explicitly mention “raid”).
Back to the main menu, a new virtual “RAID” disk appears. This disk is presented with a single partition which can not be deleted, but whose use we can choose (just like for any other partition).
For further details on RAID functions, please refer to ???.
Configuring the Logical Volume Manager (LVM)
LVM
Logical Volume Manager
Logical Volume Manager
during installation
LVM allows you to create “virtual” partitions that span over several disks. The benefits are twofold: the size of the partitions are no longer limited by individual disks but by their cumulative volume, and you can resize existing partitions at any time, possibly after adding an additional disk when needed.
LVM uses a particular terminology: a virtual partition is a “logical volume”, which is part of a “volume group”, or an association of several “physical volumes”. Each of these terms in fact corresponds to a “real” partition (or a software RAID device).
volume
logical volume
volume
physical volume
group
of volumes
volume
group
This technique works in a very simple way: each volume, whether physical or logical, is split into blocks of the same size, which are made to correspond by LVM. The addition of a new disk will cause the creation of a new physical volume, and these new blocks can be associated to any volume group. All of the partitions in the volume group that is thus expanded will have additional space into which they can extend.
The partitioning tool configures LVM in several steps. First you must create on the existing disks the partitions that will be “physical volumes for LVM”. To activate LVM, you need to choose “Configure the Logical Volume Manager (LVM)”, then on the same configuration screen “Create a volume group”, to which you will associate the existing physical volumes. Finally, you can create logical volumes within this volume group. Note that the automatic partitioning system can perform all these steps automatically.
In the partitioning menu, each physical volume will appear as a disk with a single partition which can not be deleted, but that you can use as desired.
The usage of LVM is described in further detail in ???.
Setting Up Encrypted Partitions
LUKS
dm-crypt
partition
encrypted
partition encryption
confidentiality
files
file
confidentiality
To guarantee the confidentiality of your data, for instance in the event of the loss or theft of your computer or a hard drive, it is possible to encrypt the data on some partitions. This feature can be added underneath any filesystem, since, as for LVM, Linux (and more particularly the dm-crypt driver) uses the Device Mapper to create a virtual partition (whose content is protected) based on an underlying partition that will store the data in an encrypted form (thanks to LUKS, Linux Unified Key Setup, a standard format that enables the storage of encrypted data as well as meta-information that indicates the encryption algorithms used).
To create an encrypted partition, you must first assign an available partition for this purpose. To do so, select a partition and indicate that it is to be used as a “physical volume for encryption”. After partitioning the disk containing the physical volume to be made, choose “Configure encrypted volumes”. The software will then propose to initialize the physical volume with random data (making the localization of the real data more difficult), and will ask you to enter an “encryption passphrase”, which you will have to enter every time you boot your computer in order to access the content of the encrypted partition. Once this step has been completed, and you have returned to the partitioning tool menu, a new partition will be available in an “encrypted volume”, which you can then configure just like any other partition. In most cases, this partition is used as a physical volume for LVM so as to protect several partitions (LVM logical volumes) with the same encryption key, including the swap partition (see sidebar sidebar_title).
Installing the Base System
system
base
This step, which doesn't require any user interaction, installs the Debian “base system” packages. This includes the dpkg and apt tools, which manage Debian packages, as well as the utilities necessary to boot the system and start using it.
Configuring the Package Manager (apt)
configuration
initial configuration of APT
APT
initial configuration
In order to be able to install additional software, APT needs to be configured and told where to find Debian packages. This step is as automated as possible.
If getting packages from the network is requested, the installer allows choosing a server from which to download these packages, by choosing first a country, then a mirror available in that country. A mirror is a public server hosting copies of all the files of the Debian master archive.
Finally, the program proposes to use an HTTP proxy. If there is no proxy, Internet access will be direct. If you type http://proxy.falcot.com:3128, APT will use the Falcot proxy/cache, a “Squid” program. You can find these settings by checking the configurations of a web browser on another machine connected to the same network.
The files Packages.xz and Sources.xz are then automatically downloaded to update the list of packages recognized by APT.
Debian Package Popularity Contest
popularity-contest
package
popularity
The Debian system contains a package called popularity-contest, whose purpose is to compile package usage statistics. Each week, this program collects information on the packages installed and those used recently, and anonymously sends this information to the Debian project servers. The project can then use this information to determine the relative importance of each package, which influences the priority that will be granted to them. In particular, the most “popular” packages will be included in the installation CD-ROM, which will facilitate their access for users who do not wish to download them or to purchase a complete set.
This package is only activated on demand, out of respect for the confidentiality of users' usage.
Selecting Packages for Installation
The following step allows you to choose the purpose of the machine in very broad terms; the twelve suggested tasks correspond to lists of packages to be installed. The list of the packages that will actually be installed will be fine-tuned and completed later on, but this provides a good starting point in a simple manner.
This step can require a full set of installation media or an internet connection and a working mirror setup as described above.
Some packages are also automatically installed according to the hardware detected (thanks to the program discover-pkginstall from the discover package).
Installing the GRUB Bootloader
loader
bootloader
bootloader
GRUB
The bootloader is the first program started by the BIOS. This program loads the Linux kernel into memory and then executes it. It often offers a menu that allows the user to choose the kernel to load and/or the operating system to boot.
GRUB is the default bootloader installed by Debian thanks to its technical superiority: it works with most filesystems and therefore doesn't require an update after each installation of a new kernel, since it reads its configuration during boot and finds the exact position of the new kernel. Version 1 of GRUB (now known as “Grub Legacy”) couldn't handle all combinations of LVM and software RAID; version 2, installed by default, is more complete. While there may still be situations where it is preferable to install LILO (another bootloader); the Debian installer does no longer support the installation of it and it has also been removed from the Debian archive.
LILO
It is worth noting that GRUB is not a single bootloader, it is more like a collection of bootloaders suited for different cases. The numerous binary packages built out of the GRUB source package reflect that: grub-efi-amd64 is for 64-bit PC booting in UEFI mode, grub-efi-ia32 is for 32-bit PC booting in UEFI mode, grub-pc is for PC booting in BIOS mode, grub-uboot for ARM computers, etc.
For more information on configuring GRUB, please refer to ???.
Finishing the Installation and Rebooting
The installation is now complete, the program invites you to remove the CD-ROM from the reader and to restart the computer.
After the First Boot
If you activated the task “Debian desktop environment” without any explicit desktop choice (or with the “GNOME” choice), the computer will display the gdm3 login manager.
The user that has already been created can then log in and begin working immediately.
Installing Additional Software
apt
synaptic
The installed packages correspond to the profiles selected during installation, but not necessarily to the use that will actually be made of the machine. As such, you might want to use a package management tool to refine the selection of installed packages. The two most frequently used tools (which are installed if the “Debian desktop environment” profile was chosen) are apt (accessible from the command line) and synaptic (“Synaptic Package Manager” in the menus).
To facilitate the installation of coherent groups of programs, Debian creates “tasks” that are dedicated to specific uses (mail server, file server, etc.). You already had the opportunity to select them during installation, and you can access them again thanks to package management tools such as aptitude (the tasks are listed in a distinct section) and synaptic (through the menu ).
aptitude
Aptitude is an interface to APT in full-screen text mode. It allows the user to browse the list of available packages according to various categories (installed or not-installed packages, by task, by section, etc.), and to view all of the information available on each of them (dependencies, conflicts, description, etc.). Each package can be marked “install” (to be installed, + key) or “remove” (to be removed, - key). All of these operations will be conducted simultaneously once you've confirmed them by pressing the g key (“g” for “go!”). If you have forgotten some programs, no worries; you will be able to run aptitude again once the initial installation has been completed.
Of course, it is possible not to select any task to be installed. In this case, you can manually install the desired software with the apt or aptitude command (which are both accessible from the command line). The packages can be found using the apt-cache search task keyword command.
Upgrading the System
safe-upgrade
A first apt upgrade (a command used to automatically update installed programs) is generally required, especially for possible security updates issued since the release of the latest Debian stable version. These updates may involve some additional questions through debconf, the standard Debian configuration tool. For further information on these updates conducted by apt, please refer to ???.
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