Debian 11 on Oracle Cloud (Free Tier) - (ARM64)

oci_ubuntu_to_debian.multiarch.sh

# clean arm64/amd64 instance with (ubuntu 22.04 minimal)
# all actions require root privileges (aka "sudo -i")
export DEBIAN_FRONTEND=noninteractive; apt update && apt install lsof

# prepare
snap remove --purge oracle-cloud-agent && snap remove --purge core18 && \
apt-get purge -y $(dpkg-query -Wf '${Package}\n' | grep header) $(dpkg-query -Wf '${Package}\n' | grep -oP "^linux.*\d\d\d\d-oracle" | grep -v "$(uname -r)") linux-modules-extra-$(uname -r) lxc* lxd* vim* snapd* python* && \
apt-get -y autoremove --purge && apt-get -y autoclean && rm -rf /var/log/* /var/lib/apt/* /var/cache/apt/* && cd / && \
mount -t tmpfs -o size=1700m tmpfs mnt && tar --one-file-system -c . | tar -C /mnt -x && \
mount --make-private -o remount,rw / && \
mount --move dev mnt/dev && mount --move proc mnt/proc && \
mount --move run mnt/run && mount --move sys mnt/sys && \
sed -i '/^[^#]/d;' mnt/etc/fstab && \
echo 'tmpfs / tmpfs defaults 0 0' >> mnt/etc/fstab && \
cd mnt && mkdir old_root && \
mount --make-private /

# manual
unshare -m
pivot_root . old_root

# start sshd on 1022 (you need to reconnect to this ssh instance for the next steps)
iptables -I INPUT -p tcp -m state --state NEW -m tcp --dport 1022 -j ACCEPT ; /usr/sbin/sshd -D -p 1022 &

# killall
for i in agetty dbus-daemon atd iscsid rpcbind unattended-upgrades; do pkill $i; done
kill 1 
umount -l /dev/sda1

# debian 11 install (for ARM64/aarch64)
curl -L https://cloud.debian.org/cdimage/cloud/bullseye/latest/debian-11-genericcloud-arm64.tar.xz | tar -OJxvf - disk.raw | dd of=/dev/sda bs=1M && sleep 10 && sync && echo "Done! Go reboot" && echo b | tee /proc/sysrq-trigger

# done
# default user now is "debian"

#in new system (deb11)

export DEBIAN_FRONTEND=noninteractive
echo "deb http://deb.debian.org/debian bullseye main contrib non-free
deb http://deb.debian.org/debian bullseye-updates main contrib non-free
deb http://deb.debian.org/debian bullseye-backports main contrib non-free
deb http://security.debian.org/debian-security/ bullseye-security main contrib non-free" > /etc/apt/sources.list && \
apt update && apt full-upgrade -y && \
sed -i '/en_US.UTF-8/s/^# //g' /etc/locale.gen && locale-gen && update-locale LANG=en_US.UTF-8 && \
apt install -y htop && reboot