====== Upgrade Debian 10 to Debian 11 ======
This walk-through explains the steps to upgrade from Debian 10 to Debian 11. Since I had to upgrade my motherboard (after 16 years of operation!) (see [[hw:machines#epione|Machines]]) I could not access the internet before upgrading Debian to //Bullseye//. In my specific case this is because the //B550m// motherboard from Asrock is equipped with a Realtek RTL8111H NIC which is only supported in kernels newer than 4.19, and Debian 10 is still based on Linux kernel 4.19. Several attempts to install a newer Realtek driver failed, therefore I decided to upgrade to Debian 11 offline through an iso image.

===== Steps =====
  - Backup essential folders and files
    * ''/etc''
    * ''/var/lib/dpk''
    * ''/var/lib/apt/extended_states''
    * output of ''dpkg --get-selections "*"''<file>sudo dpkg --get-selections "*" > selections</file>
    * ''/home'' directory and hidden files to prevent some applications from overwriting existing user settings with new defaults
  - Download [[https://www.debian.org/CD/http-ftp/|Debian iso]] file and copy it to your host's home directory. Make sure you download the iso containing all desktop environments, or the one matching your installed desktop environment.
  - Add the iso file to fstab so it will mount when rebooting. At the bottom of fstab enter the following line:<file>/home/user/debian-11.6.0-amd64-DVD-1.iso /media/cdrom/ iso9660 loop 0 0</file>
  - Record the session. It is strongly recommended that you use the /usr/bin/script program to record a transcript of the upgrade session. Then if a problem occurs, you will have a log of what happened, and if needed, can provide exact information in a bug report. To start the recording, type:<file>script -t 2>~/upgrade-bullseye1.time -a ~/upgrade-bullseye1.script</file>
  - Do a minimal system upgrade first:<file>sudo apt upgrade --without-new-pkgs</file>
  - Avoid libreoffice to be installed. Hold the package:<file>sudo apt-mark hold libreoffice*</file>
  - Do the distro upgrade:<file>sudo apt full-upgrade</file>
  - Remove the hold:<file>sudo apt-mark unhold libreoffice*</file>Show all packages on hold:<file>sudo apt-mark showhold</file>
  - After you have completed the upgrade, you can stop script by typing exit at the prompt. If you have used the -t switch for script you can use the scriptreplay program to replay the whole session:<file>sudo scriptreplay ~/upgrade-bullseyestep.time ~/upgrade-bullseyestep.script</file>
  - Remove folders which should but could not be removed during the upgrade
  - Remove obsolete packages<file>sudo apt autoremove</file>
  - Configure NIC:<file>sudo vim /etc/network/interfaces</file>Replace content with:<file># The loopback network interface
auto lo
iface lo inet loopback
 
# The primary network interface
auto enp0s5
iface enp0s5  inet static
 address 192.168.2.236
 netmask 255.255.255.0
 gateway 192.168.2.254
 dns-domain sweet.home
 dns-nameservers 192.168.2.254</file>
  - Reboot, then check internet is accessible
  - Change host name<file>sudo hostnamectl set-hostname <new-host-name>
sudo vim /etc/hosts</file>

===== Links =====
  * Upgrade without internet [[https://unix.stackexchange.com/questions/680652/how-to-upgrade-debian-10-to-debian-11-without-internet#answers-header|How to upgrade Debian 10 to Debian 11 without internet?]]
  * Mount iso [[https://www.cyberciti.biz/tips/how-to-mount-iso-image-under-linux.html|How to mount an ISO image/file under Linux]]
  * Mount using fstab:[[https://itekblog.com/mount-iso-using-fstab/|Mount ISO using fstab (Linux tutorial)]]
  * Backup [[https://phoenixnap.com/kb/upgrade-debian-10-to-11#ftoc-heading-2|How to Upgrade Debian 10 to Debian 11]]
  * Debian [[https://www.debian.org/releases/stable/amd64/release-notes/ch-upgrading.en.html#cdroms|Upgrades from Debian 10 (buster)]]
  * Network [[https://www.cyberciti.biz/faq/linux-list-network-interfaces-names-command/|Linux Show / Display Available Network Interfaces]]
  * Network [[https://www.cyberciti.biz/faq/add-configure-set-up-static-ip-address-on-debianlinux#attachment_149351|How to set up static IP address on Debian Linux 10/11]]
  * Apt sources [[https://techviewleo.com/add-debian-11-bullseye-official-repositories-to-sources-list/|Add Debian 11 Bullseye official repositories to sources.list]]
  * Hold packages [[https://askubuntu.com/questions/18654/how-to-prevent-updating-of-a-specific-package|How to prevent updating of a specific package?]]
  * Host name [[https://www.cyberciti.biz/faq/how-to-change-hostname-on-debian-10-linux/|Change hostname on Debian]]