How to Replace Systemd With SysV Init On Debian Linux

Objective

Replace systemd with SysV Init as the init system on Debian Stretch

Distributions

Debian Stretch

Requirements

A working Debian Stretch install with root privileges.

Difficulty

Medium

Conventions

• # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
• $ - requires given linux commands to be executed as a regular non-privileged user

Introduction

Not everyone loves systemd, and for those that don't, there really aren't many options. That's especially true if you want something like a stable server. Fear not, SysV Init is actually still supported under Debian, and it's not hard to switch.

**Note:** don't try this if you're running GNOME or another desktop environment that has a hard dependency on systemd. It will just break your system.

Add Devuan Repositories

This part isn't strictly necessary if you just want to switch the init system and leave systemd installed as a compatibility layer. That would work fine. If you absolutely don't want systemd on your system at all, you need to make some arrangements to make the things that depend on it work.

Devuan, the systemd-less Debian fork is lagging a bit behind. Their Stretch release, ASCII, isn't ready, and running Devuan's testing releases isn't super stable right now. However, the did build some crucial packages to make systemd-dependent programs work without it, and you can use them in Debian.

First, create a new .list file in /etc/apt/sources.list.d/ for Devuan. Then, add the following line to it.

deb http://packages.devuan.org/devuan/ ascii main

Save that and exit.

Next, you're going to need the Devuan signing key. Grab that with wget.

$ cd Downloads
$ wget https://devuan.org/os/keyring/This email address is being protected from spambots. You need JavaScript enabled to view it.

Then, import it into Apt.

# apt-key add This email address is being protected from spambots. You need JavaScript enabled to view it.

Pin The Devuan Packages

Unless you want a really weird Debian/Devuan hybrid, you're going to need to pin only the Devuan packages that you need. Create a file, devuan.list, at /etc/apt/preferences.d/. Add the following lines to it.

Package: *
Pin: release a=stable
Pin-Priority: 1000

Package: *
Pin: release a=ascii
Pin-Priority: 2

Package: udisks2
Pin: release a=ascii
Pin-Priority: 1001

Package: libudisks2-0
Pin: release a=ascii
Pin-Priority: 1001

Package: cgmanager
Pin: release a=ascii
Pin-Priority: 1001

Package: libcgmanager0
Pin: release a=ascii
Pin-Priority: 1001

Package: libpolkit-agent-1-0
Pin: release a=ascii
Pin-Priority: 1001

Package: libpolkit-backend-1-0
Pin: release a=ascii
Pin-Priority: 1001

Package: libpolkit-gobject-1-0
Pin: release a=ascii
Pin-Priority: 1001

Package: policykit-1
Pin: release a=ascii
Pin-Priority: 1001

It's lengthy and annoying, but it'll keep a lot of things from breaking once you remove systemd. Update before moving on.

# apt update

Install The Devuan Packages

The next step is fairly straightforward. Install all of the packages you just set up for.

# apt -t ascii install udisks2 libudisks2-0 cgmanager libcgmanager0 libpolkit-agent-1-0 libpolkit-backend-1-0 libpolkit-gobject-1-0 policykit-1

Install SysV

You're finally ready to install SysV. This one is also pretty easy.

# apt install sysvinit-core sysvinit-utils

Then, copy SysV's inittab to make it the system default.

# cp /usr/share/sysvinit/inittab /etc/inittab

Once everything is in place, and you're confident that you installed everything properly, restart the system. You should see the difference immediately in the boot process.

Remove Systemd

Again, this step is totally optional and may still break things. This will pull out systemd and anything that still depends on it. You have been warned.

# apt remove  --purge --auto-remove systemd

If you want to make the change stick, add systemd to your Apt preferences.

Package: systemd
Pin: release *
Pin-Priority: -1

Closing Thoughts

That's it! You're Debian system is officially systemd-free. Hopefully, everything else still works correctly too. This method is obviously better with servers than desktops because of the amount of desktop software that relies on systemd. It's also important to keep in mind that things can change. Stretch is pretty much set in stone, but trying this procedure or an equivalent on Testing or Sid might not yield the same results.