By now, it is well known that Debian Jessie will not be using sysvinit as its boot system by default. But how can one keep using sysvinit in Jessie? It is fairly easy, and here are a few recipes, courtesy of Erich Schubert and Simon McVittie.
If you already are using Wheezy and want to upgrade to Jessie and keep sysvinit as your boot system, create a file /etc/apt/preferences.d/use-sysvinit with this content before you upgrade:
Package: systemd-sysv Pin: release o=Debian Pin-Priority: -1
This file content will tell apt and aptitude to not consider installing systemd-sysv as part of any installation and upgrade solution when resolving dependencies, and thus tell it to avoid systemd as a default boot system. The end result should be that the upgraded system keep using sysvinit.
If you are installing Jessie for the first time, there is no way to get sysvinit installed by default (debootstrap used by debian-installer have no option for this), but one can tell the installer to switch to sysvinit before the first boot. Either by using a kernel argument to the installer, or by adding a line to the preseed file used. First, the kernel command line argument:
preseed/late_command="in-target apt-get install --purge -y sysvinit-core"
Next, the line to use in a preseed file:
d-i preseed/late_command string in-target apt-get install -y sysvinit-core
One can of course also do this after the first boot by installing the sysvinit-core package.
I recommend only using sysvinit if you really need it, as the sysvinit boot sequence in Debian have several hardware specific bugs on Linux caused by the fact that it is unpredictable when hardware devices show up during boot. But on the other hand, the new default boot system still have a few rough edges I hope will be fixed before Jessie is released.
Update 2014-11-26: Inspired by