How to remove systemd from a Debian jessie/sid installation

SysV init

First install the SysV init packages:

apt-get install sysvinit-core sysvinit-utils
cp /usr/share/sysvinit/inittab /etc/inittab

Then reboot your machine and remove all of the systemd packages. BE AWARE that the following command removes packages that depend on systemd itself or things like libpam-systemd!

apt-get remove --purge --auto-remove systemd

Prevent apt from installing systemd packages in the future.

echo -e 'Package: systemd\nPin: release *\nPin-Priority: -1' > /etc/apt/preferences.d/systemd

Prevent apt from installing any systemd like packages in the future (note the star before and after systemd)

echo -e '\n\nPackage: *systemd*\nPin: release *\nPin-Priority: -1' >> /etc/apt/preferences.d/systemd

Note: This prevents the installation of the package systemd-shim as well. However this is a emulation of systemd functions, so you can install software which depends on systemd. So if you get "Package systemd-shim is not available, but is referred to by another package." you might temporary disable the three lines in the preferences.d/systemd file.

In the case your system uses multiarch (mixed 32 and 64bit packages), you need to pin the 64bit version of systemd too. Otherwise apt-get could still install it as dependency later.

echo -e '\nPackage: systemd:amd64\nPin: release *\nPin-Priority: -1' >> /etc/apt/preferences.d/systemd

In other multiarch cases where amd64 is the default architecture, you may have to pin the i386 package to prevent APT from installing it:

echo -e '\nPackage: systemd:i386\nPin: release *\nPin-Priority: -1' >> /etc/apt/preferences.d/systemd

polkit

To enable polkit based stuff (suspend, hibernate, mount via gvfs etc.), the following procedure can be used.

Warning: tested with lightdm on jessie only!

Add wheezy repo to apt lists:

echo deb http://ftp.debian.org/debian/ wheezy main contrib non-free >/etc/apt/sources.list.d/wheezy.list

Pin essential packages to wheezy:

echo -e '\n\nPackage: policykit-1\nPin: origin "wheezy"\nPin-Priority: -1' >> /etc/apt/preferences.d/systemd
echo -e '\n\nPackage: libpolkit-*\nPin: origin "wheezy"\nPin-Priority: -1' >> /etc/apt/preferences.d/systemd
echo -e '\n\nPackage: upower\nPin: origin "wheezy"\nPin-Priority: -1' >> /etc/apt/preferences.d/systemd

Note: for multiarch system you may need also to pin 64bit and i386 versions separately as mentioned above.

Install polkit-1 with libs, upower and udisks (not udisks2!)

apt-get install polkit-1 libpolkit-agent-1-0 libpolkit-backend-1-0 libpolkit-gobject-1-0 upower udisks

Install policykit authentication agent depending on what desktop environment you use:

apt-get install policykit-1-gnome                                   # For GNOME or XFCE4
apt-get install mate-polkit                                         # For MATE
apt-get install lxsession                                           # For LXDE

Reboot or restart your *dm service.