Hello,

The following instructions is the first version of how to migrate from
Debian/Buster to Devuan/Beowulf.
Note that this description does use a fixed network interface. For
wireless connections additional tips should be made.

The following text file describes the procedure:
(replacing Debian's gnome desktop (default) with Devuan's mate)

apt-get install emacs-nox
apt-get install net-tools
emacs -nw ~srs/.bashrc
+ export PATH=$PATH:/sbin:/usr/sbin
ifconfig
ens3 ...

Remove debian entries in sources.list
emacs /etc/apt/sources.list
deb http://deb.devuan.org/merged beowulf main
deb http://deb.devuan.org/merged beowulf-security main
deb http://deb.devuan.org/merged beowulf-updates main
deb http://deb.devuan.org/devuan beowulf-proposed main

wget
https://pkgmaster.devuan.org/devuan/pool/main/d/devuan-keyring/devuan-keyring_2017.10.03_all.deb
dpkg -i devuan-keyring_2017.10.03_all.deb

apt-get update
apt-get upgrade
<not a good idea since systemd will still be pid 1>

apt-get install sysvinit-core
The following packages will be REMOVED: 71
The following NEW packages will be installed:
initscripts insserv libeudev1 libpolkit-gobject-consolekit-1-0
startpar
sysv-rc sysvinit-core
The following packages will be upgraded:
gir1.2-polkit-1.0 libpolkit-agent-1-0 libudev1 task-british-desktop
task-english task-ssh-server tasksel tasksel-data
8 upgraded, 7 newly installed, 71 to remove and 34 not upgraded.
Need to get 707 kB of archives.
After this operation, 383 MB disk space will be freed.
Do you want to continue? [Y/n] Y

Note: Abort the upgrade since the kernel is about to be removed!!
apt --fix-broken install
The following additional packages will be installed:
elogind eudev gir1.2-polkit-1.0 initramfs-tools initramfs-tools-core
initscripts insserv libelogind0 libeudev1 libpam-elogind libpolkit-
agent-1-0
libpolkit-backend-elogind-1-0 libpolkit-gobject-elogind-1-0 libudev1
pigz
policykit-1 policykit-1-gnome startpar sysv-rc sysvinit-core udev
xserver-xorg-core
he following packages will be REMOVED:
iio-sensor-proxy libnss-systemd libsystemd0 systemd
The following NEW packages will be installed:
elogind eudev initramfs-tools initramfs-tools-core initscripts
insserv
libelogind0 libeudev1 libpam-elogind libpolkit-backend-elogind-1-0
libpolkit-gobject-elogind-1-0 pigz policykit-1 policykit-1-gnome
startpar
sysv-rc sysvinit-core udev xserver-xorg-core
The following packages will be upgraded:
gir1.2-polkit-1.0 libpolkit-agent-1-0 libudev1
3 upgraded, 19 newly installed, 4 to remove and 39 not upgraded.
Need to get 6,122 kB/6,667 kB of archives.
After this operation, 5,341 kB of additional disk space will be used.
Do you want to continue? [Y/n] Y
Removing systemd (241-7~deb10u7) ...
systemd is the active init system, please switch to another before
removing systemd.
Manual FIX:
dpkg -i /var/cache/apt/archives/sysvinit-core_2.93-8+devuan1_amd64.deb
/var/cache/apt/archives/initscripts_2.93-8+devuan1_amd64.deb
/var/cache/apt/archives/sysv-rc_2.93-8+devuan1_all.deb
/var/cache/apt/archives/insserv_1.18.0-2_amd64.deb
/var/cache/apt/archives/startpar_0.61-1_amd64.deb

Alternately:
mkdir sysvinit
cd sysvinit
apt-get download sysvinit-core initscripts sysv-rc inssserv startpar
dpkg -i *.deb
cd ..
Not restarting sysvinit
<reboot> <long delay>
Console comes up <no graphical login>
log in to console: Extremely slow response
reboot into recovery mode:
error while loading shared libraries libsystemd.so.0
dpkg -i /var/cache/apt/archives/libelogind0_241.4-2_amd64.deb
apt --fix-broken-install
The following packages will be removed:
systemd
The following NEW packages will be installed:
elogind eudev initramfs-tools initramfs-tools-core libeudev1 libpam-
elogind libpolkit-backend-elogind libpolkit-gobject-elogind-1-0 pigz
policykit-1-gnome udev xserver-xorg-coreThe following packages will be
upgraded:
gir1.2-polkit-1.0 libpolkit-agent-1-0 libudev1
emacs /etc/network/interfaces
# The primary network interface
auto /dev/eth0
iface /dev/eth0 inet dhcp
<reboot>
ssh and network OK
apt-get upgrade
The following packages will be upgraded:
base-files bsdutils colord-data dbus dbus-x11 distro-info-data fdisk
gir1.2-packagekitglib-1.0 init init-system-helpers libblkid1
libcolord2
libcolorhug2 libdbus-1-3 libfdisk1 libmount1 libpackagekit-glib2-18
libpcsclite1 libpolkit-backend-1-0 libpolkit-gobject-1-0 libprocps7
libsmartcols1 libudisks2-0 libuuid1 mount net-tools procps python3-
reportbug
reportbug rsyslog sysvinit-utils task-british-desktop task-english
task-ssh-server tasksel tasksel-data util-linux util-linux-locales
38 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
Need to get 7,404 kB/7,522 kB of archives.
After this operation, 2,461 kB of additional disk space will be used.
Do you want to continue? [Y/n] Y
apt-get dist-upgrade
The following NEW packages will be installed:
cinnabar-icon-theme clearlooks-phenix-cinnabar-theme dmz-cursor-theme
gnome-extra-icons gnome-icon-theme gtk2-engines gtk3-
nooverlayscrollbar
The following packages will be upgraded:
desktop-base
1 upgraded, 7 newly installed, 0 to remove and 0 not upgraded.
Need to get 17.1 MB of archives.
After this operation, 22.7 MB of additional disk space will be used.
Do you want to continue? [Y/n] Y

apt-get install linux-image-amd64
apt-get autoremove --purge
<reboot>
apt-get install task-mate-desktop
0 upgraded, 347 newly installed, 0 to remove and 0 not upgraded.
Need to get 332 MB/332 MB of archives.
After this operation, 1,292 MB of additional disk space will be used.
Do you want to continue? [Y/n] Y
...
<login OK to lightdm/mate>