Bullseye release notes / install instructions for alternative inits

[Mark Hindley]

Matthew,

Thanks.

On Fri, Jul 23, 2021 at 10:23:22AM +0100, Matthew Vernon wrote:
> Switching init system
> 
> The default init system in Debian is systemd. In bullseye, a number of
> alternative init systems are supported (such as System-V-style init and
> OpenRC). Generally, to switch between init systems, you install the new init
> system and reboot. The exception is switching away from systemd - systemd's
> packages will refuse to be removed if systemd is running; so the process is
> a little more involved.
> 
> In outline, you need to download the new packages you need, switch to
> single-user mode, install these new packages, and then reboot. The
> recommended approach is as follows. First, clear out
> `/var/cache/apt/archives` by running `apt-get clean` (this makes identifying
> the packages to install later easier). Next, get `apt` to download the new
> packages you need, e.g.: `apt-get --download-only install sysvinit-core
> libpam-elogind`; libpam-elogind (and elogind which it Depends upon) provide
> session management facilities, which you will likely need on any system
> running a desktop environment. At this point, review apt's proposed actions,
> and if happy, let it carry on.
> 
> Now switch to single-user mode (`systemctl rescue`) and install the packages
> you downloaded using `dpkg -i`; the packages will be in
> `/var/cache/apt/archives`. Once dpkg has completed, reboot your system.

I have battled with finding a good way to do this for ages and not thought of
this approach. Looks good, thanks.

Mark