Debian base installation¶

Introduction ¶

These are my notes about the installation of a Debian GNU/Linux system on a 64-bit (“AMD64” architecture) PC. A significant part of these notes describe the preparation of the installation medias. The assumption is made that you have access to a working machine with a Debian GNU/Linux system installed and a fast enough internet connection (to download a few hundreds of megabytes). This machine will be used to prepare the installation medias for the new system.

Many software packages are also downloaded during the installation, so the target machine should also have a fast enough internet connection.

Getting an installation CD ¶

See the Getting Debian page for information about how to download a Debian installer CD image or buy installation CDs.

If you have a fast enough internet connection and a CD burning drive, you can download a small (approximately 300MB) installation image and burn it to a blank CD-R. Commands like the ones below should do it. The example is for Debian 12.4.0 (Bookworm). Note also that it is assumed that you have cdrskin installed. Run apt-get install cdrskin as root if not. Note also that the dev=<cd_burning_drive_device_file> option is probably not mandatory as cdrskin can detect CD burning devices (cdrskin --devices lists the detected devices):

wget https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-12.4.0-amd64-netinst.iso
cdrskin dev=<cd_burning_drive_device_file> -eject -v -data debian-12.4.0-amd64-netinst.iso

You might want to verify the authenticity of the ISO image. Download the SHA512 checksum and associated signature file:

wget https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/SHA512SUMS
wget https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/SHA512SUMS.sign

Then, attempt to verify the authenticity of the image:

gpg --verify SHA512SUMS.sign

If there are lines like the following in the output, it means that you have never imported the key used to sign the image (and this is confirmed by the fact that it does not appear in the output of gpg --list-keys).

gpg: using RSA key DF9B9C49EAA9298432589D76DA87E80D6294BE9B

gpg: Can’t check signature: No public key

You can import the key with:

gpg --keyserver keyring.debian.org --recv DF9B9C49EAA9298432589D76DA87E80D6294BE9B

A new attempt to check the signature with gpg --verify SHA512SUMS.sign now produces a line like

gpg: Good signature from “Debian CD signing key <debian-cd@lists.debian.org>”

When the burning is done, you might also want to check the integrity of the burned CD. Just compare the output of the following command with the checksum from the downloaded checksum file as provided in file SHA512SUMS:

dd if=/dev/<cd_burning_drive_device_file> bs=2048 \
  count=$(($(stat -c %s debian-12.4.0-amd64-netinst.iso)/2048)) \
  conv=notrunc,noerror | sha512sum

Preparing a media with firmware archive, just in case ¶

Note that this step is not necessary if your installation CD already includes firmware (that is if you have downloaded the image from a subdirectory of cdimage.debian.org/cdimage/unofficial/non-free/cd-including-firmware).

Note also that this section does not apply any more, starting with Debian 12. (Firmware is now included in the normal Debian installer images.)

The Debian Wiki provides some instructions, but here are the details of what I’ve done (for a Debian Bookworm install, and including the authenticity verification of the archive):

mkdir -p ~/download/debian_bookworm_firmware # Create a directory somewhere.
cd ~/download/debian_bookworm_firmware       # Move to that directory.

# Download the firmware archive, its SHA512 checksum and associated signature
# file.
wget http://cdimage.debian.org/cdimage/unofficial/non-free/firmware/bookworm/current/firmware.tar.gz
wget http://cdimage.debian.org/cdimage/unofficial/non-free/firmware/bookworm/current/SHA512SUMS
wget http://cdimage.debian.org/cdimage/unofficial/non-free/firmware/bookworm/current/SHA512SUMS.sign

I’ve checked the SHA512 checksum of firmware.tar.gz by issuing a sha512sum -c --ignore-missing SHA512SUMS.

I’ve checked the signature by issuing a gpg --verify SHA512SUMS.sign command.

The final steps consisted in extracting the files from the firmware archive (tar xvzf firmware.tar.gz) and copy all the files with .deb extension to a “firmware” directory located at the root of a USB stick.

During Debian installation, plug in this USB stick when (and if) you get this kind of screen:

_images/debian_install_screenshot_hw-detect_load_firmware_0.png

Disk partitioning ¶

Choosing the amount of swap space ¶

I tend to follow the recommendations provided in this article by Abhishek Prakash: https://itsfoss.com/swap-size.

Choosing the partitioning scheme ¶

When disk encryption is not wanted (and with legacy BIOS mode boot)¶

If the machine has only one hard drives, I choose a simple partitioning scheme: a single / partition plus a swap partition. I find it easy enough to set up (using either the “Guided - use entire disk” or “manual” method proposed by the Debian installer).

If the machine has one SSD and one traditional spinning hard disk drive, I choose the following partitioning scheme:

/ partition on SSD (20GB).

/usr partition on SSD.

/var partition on spinning HDD (20GB).

/tmp partition on spinning HDD (10GB).

swap partition on spinning HDD.

/home partition on spinning HDD.

(This link was helpful: https://unix.stackexchange.com/a/89230).

When disk encryption is wanted (and with UEFI mode boot)¶

I’ve setup disk encryption once on a 2022 laptop with a single hard drive. I’ve done it using the “Guided - use entire disk and set up encrypted LVM” method proposed by the Debian installer. It is of course possible to do it using the “manual” method, but I find it too easy to forget something (e.g. ESP partition, /boot partition).

I struggled to set up the wanted swap space size, but eventually understood I had to go into “Configure the Logical Volume Manager”, delete the logical volumes and create them again with the wanted sizes.

Postponing the installation of a graphical environment ¶

During Debian installation, you arrive at this screen.

_images/debian_install_screenshot_tasksel_first_0.png

Checking none of the desktop environment results obviously in no desktop environment installed. But it is possible to install one (including one that was not proposed by the Debian installer) later.

Shutting down and rebooting a Debian system ¶

After the installation, you should be able to boot into the newly installed system and log in as root or normal user. But it may not be obvious how to shutdown or reboot the system:

systemctl poweroff # Shut down.
systemctl reboot   # Reboot.

You can delay the execution of the command:

system-run --on-active=90 systemctl poweroff # Shut down in 90 seconds.

Alternatively, you can use the shutdown command:

shutdown    # Power-off the machine in 1 minute.
shutdown +2 # Power-off the machine in 2 minutes.

Immediate post-install actions ¶

This section describes what I usually do after booting into the newly installed Debian system.

Fixing the slow boot issue ¶

A former machine of mine was affected by the TSSTcorp CDDVDW SH-S223C related slow boot issue. You can check if you have this particular CD/DVD-RW drive with this command (assuming your optical drive is associated with device /dev/sr0):

udevadm info -a -p  $(udevadm info -q path -n /dev/sr0) | grep model

The fix involves changing file /lib/udev/rules.d/60-persistent-storage.rules and then regenerating the initramfs image (as root for both operations):

update-initramfs -u # As root, regenerates the initramfs image.

As for the change to /lib/udev/rules.d/60-persistent-storage.rules, the internet gives two solutions:

Commenting out entirely the ATAPI device rule using this command:

sed -i '/ATAPI/,+1s/^/#/' /lib/udev/rules.d/60-persistent-storage.rules # As root.

Cancelling the rule for the SH-S223C only, as suggested in Debian bug #622340. This is what I was doing.

Note that the change to /lib/udev/rules.d/60-persistent-storage.rules and the regenration of the initramfs image have to be redone after each update of the udev Debian package (because /lib/udev/rules.d/60-persistent-storage.rules is overwritten and the initramfs image regenerated by the update).

System update ¶

Update the system as root with:

apt-get update       # As root.
apt-get dist-upgrade # As root.

After an update, the presence of file /var/run/reboot-required indicates that a reboot is required due to a new kernel or to the update of a critical library.

Preventing the system from beeping ¶

The newly installed system may emit beeps quiet often (for example when working in a terminal emulator). To stop that, you can blacklist module pcspkr by adding a file as root in /etc/modprobe.d (file name suggestion: nobeep.conf). The file should contain this line:

blacklist pcspkr

After rebooting the system, module pcspkr should not be loaded any more (i.e. lsmod | grep pcspkr should output nothing) and you should not hear beeps any more.

Adding support for other languages ¶

When installing the system, I select the English language, but I sometimes want to see an application in French. So I run (as root):

dpkg-reconfigure locales # As root.

and select the french language (and don’t unselect anything).

Then if I occasionally want to run an application (e.g. Gimp) in French, I can do (as “normal” user):

export LANG=fr_FR.UTF-8
export LANGUAGE=fr_FR.UTF-8
gimp &

More details on the locales on the Debian Wiki locale page

Adding deb-multimedia to the sources ¶

You may want to add deb-multimedia as a source of packages for the newly installed Debian system (see this linuxconfig.org article).

http://deb-multimedia.org provides some instructions:

First, add as root a line like this one (example for Debian bookworm) in your /etc/apt/sources.list:

deb https://www.deb-multimedia.org bookworm main non-free

Then, issue as root the following commands:

apt-get update -oAcquire::AllowInsecureRepositories=true
apt-get install deb-multimedia-keyring
apt-get update
apt-get dist-upgrade

Installing firmware-linux-nonfree ¶

Depending on your hardware, you may not need the firmware-linux-nonfree. On my machines, this package makes life easier (most notably with Wi-Fi network adapter and/or graphics) and is installed either during installation (if the firmware archive has been required) or post-installation, manually:

apt-get install firmware-linux-nonfree # As root.

Note that the /etc/apt/sources.list file must have the non-free section (and even the non-free-firmware section, starting with Debian 12).

You can download my /etc/apt/sources.list for Debian 12.

Make sure you issue a apt-get update command after changing /etc/apt/sources.list.

Checking the configured time zone ¶

Check the configured time zone with:

cat /etc/timezone

If the configuration is not correct, you can change it as root with:

dpkg-reconfigure tzdata # As root.

Cheking systemd-timesyncd service ¶

Service systemd-timesyncd (network time synchronization service) should have been automatically enabled:

systemctl status systemd-timesyncd

The service logs its initial synchronization to /var/log/syslog. Check (as root) with:

grep systemd-timesyncd /var/log/syslog

You can find the lastest synchronization date by checking the modification time of file /run/systemd/timesync/synchronized:

stat /run/systemd/timesync/synchronized|grep ^Modif

The configuration file for systemd-timesyncd is /etc/systemd/timesyncd.conf.

Installing a console locker ¶

There are many screen and/or console locker programs. I’ve installed physlock:

apt-get install physlock # As root.

Installing a memory (RAM) tester ¶

RAM failures are not so rare in my experience. A tester like Memtest86+ can really help diagnosing a RAM failure. The apt-get install command below installs Memtest86+ and adds an entry in the Grub menu (you have to reboot your machine and select the Memtest86+ grub entry to start Memtest86+):

apt-get install memtest86+ # As root.

On one of my machines (a 2022 laptop), Memtest86+ did not work (black screen, possibly because Secure Boot was enabled). I tried Memtest86, more precisely its (unsupported) ISO image, which worked.

I downloaded and burned the ISO image to a blank CD-R using the following commands:

wget https://www.memtest86.com/downloads/memtest86-iso.zip
unzip memtest86-iso.zip
cdrskin -eject -v -data memtest86-iso.iso

Installing a wireless devices status management tool ¶

On a laptop computer, it may be useful to check the status (enabled, hard blocked, soft blocked) of the wireless devices. Package rfkill makes that possible:

apt-get install rfkill # As root.

Check the statuses with:

/usr/sbin/rfkill list

Installing a CD burning tool ¶

I use cdrskin to burn CDs (in particular the Debian installation CDs) on an internal or external (USB) CD burning drive:

apt-get install cdrskin # As root.

Creating new users ¶

Check whether the DIR_MODE (default permissions for users home directories) setting in file /etc/adduser.conf is appropriate for your needs. The default value is “0755”. It implies that any unprivileged user have read access to the files of other users. You may want to change (as root) the value to “0750” to avoid that:

sed -i s/DIR_MODE=0755/DIR_MODE=0750/ /etc/adduser.conf

Then, to create a new user, just use the adduser script (as root):

adduser new_user_name

If some users have already been created with inappropriate home directories permissions, you can update their home directories permissions with a command like (as root):

chmod 750 /home/*

Creating a “super user” account, disabling root login ¶

You may want, for security reasons, to use an account other than root to perform administrative tasks (via sudo), and to disable root login.

Make sure sudo is installed:

apt-get install sudo

Create (as root) a new user (the new “super user”):

adduser super_user_user_name

Add (as root) the “super user” to the sudo group:

usermod -aG sudo super_user_user_name

Disable root login (as the “super user”, via sudo):

sudo usermod -L root

Installing locate / updatedb ¶

Command locate is a way of finding files on your computer. It is faster than find. It relies on a database generated using program updatedb. The database is updated daily via the script /etc/cron.daily/locate (directory /etc/cron.daily should appear in file /etc/crontab).

Install locate and updatedb with:

apt-get install locate # As root.

If you don’t leave your machine running all the time, the database update may not happen every day if package anacron is not installed. You can install it (as root) with:

apt-get install anacron # As root.

You can force the database update as root with:

updatedb # As root.

You can see various statistics about the database, including the last time it has been changed, with option -S:

locate -S

If the users home directories are not world-readable, then the files they contained won’t appear in the database. In this case, users may want to generate their own database, with a command like:

updatedb --output=/home/$USER/.locatedb 2>/dev/null

Users can use the -d option of command locate to search in their database. The database contains the files in their home directory and also the system files they have permissions to see:

locate -d ~/.locatedb <search_pattern>

Users can add an entry to their crontab to automate the generation of their database. See the Reminder page for an example of crontab entry.

Post-install maintenance ¶

I regularly run the following commands to keep the system up to date:

apt-get update && apt-get dist-upgrade
apt-get autoremove # Useful if some packages have become unneeded.
apt-get autoclean  # Useful to avoid that the APT cache grows out of control.

The package management system (APT) logs to files in /var/log/apt. /var/log/apt/term.log is not easy to read due to ^M characters. When I need to read it, I make a copy of it and edit the copy in Vim to remove the ^M characters (:%s/<Crl-V><Ctrl-M>/\r/g).

After, say, a major upgrade, you might want to find which of your configuration files are different from the default configuration files. I wrote the following shell script which helps answering the question.

It’s meant to be run as root, in an empty directory created for the occasion.

Here is a short description of the script:

For every installed package on the system, the script searches the .deb file (found in /var/cache/apt/archives) for the list of configuration files for the package (file conffiles in the control.tar archive of the .deb file).

For every configuration file, the default version of the file (as found in the data.tar archive of the .deb file) is compared (using diff) with the installed version.

Of course, there are some particular cases which are not handled by the script. For example, for the package openssh-server, the configuration file /etc/ssh/sshd_config is not mentionned in conffiles (and the default version is /usr/share/openssh/sshd_config).

And here is the code:

#!/bin/sh

set -o nounset
set -o errexit

APT_ARCHIVE_DIR=/var/cache/apt/archives;
CONF_FILE_LIST=conffiles;
CTRL_ARCHIVE=control.tar;

dpkg -l \
    | grep ^ii \
    | while IFS= read -r LINE; do

          LINE_TAIL="$(echo "$LINE" | sed "s/^ii\s\+//")";
          PACKAGE_NAME="$(echo "$LINE_TAIL" | sed "s/\([^ :]\+\).\+$/\1/")";
          LINE_TAIL="${LINE_TAIL#$PACKAGE_NAME}";
          LINE_TAIL="$(echo "$LINE_TAIL" | sed "s/^\(:[^ ]\+\)\?\s\+//")";
          PACKAGE_VER="$(echo "$LINE_TAIL" | sed "s/\([^ ]\+\).\+$/\1/")";
          PACKAGE_VER="$(echo "$PACKAGE_VER" | sed "s/:/%3a/g")";
          LINE_TAIL="$(echo "$LINE_TAIL" | sed "s/^[^ ]\+\s\+//")";
          PACKAGE_ARCH="${LINE_TAIL%% *}";
          PACKAGE_DEB="${PACKAGE_NAME}_${PACKAGE_VER}_${PACKAGE_ARCH}.deb";

          PACKAGE_DEB_PATH="$APT_ARCHIVE_DIR/$PACKAGE_DEB";

          if [ -f "$PACKAGE_DEB_PATH" ]; then

              rm -rf "$PACKAGE_NAME";
              mkdir "$PACKAGE_NAME";
              cd "$PACKAGE_NAME";

              cp "$PACKAGE_DEB_PATH" .;
              ar -x "$PACKAGE_DEB";

              if [ -f "$CTRL_ARCHIVE.xz" ]; then
                  COMPRESSED_CTRL_ARCHIVE=control.tar.xz;
              else
                  COMPRESSED_CTRL_ARCHIVE=control.tar.gz;
              fi;
              tar -xf "$COMPRESSED_CTRL_ARCHIVE";

              if [ -f "$CONF_FILE_LIST" ]; then

                  tar -xf data.tar.xz;

                  for CONF_FILE in $(cat "$CONF_FILE_LIST"); do
                      echo "*** $PACKAGE_NAME configuration file $CONF_FILE";
                      set +o errexit
                      diff "$CONF_FILE" "${CONF_FILE#/}";
                      set -o errexit
                  done;
              fi;

              cd ..;
              rm -rf "$PACKAGE_NAME";

          else

              echo "Cannot find $PACKAGE_DEB_PATH" 1>&2;

          fi;

      done;