[conspire] Debian - and NOT systemd! :-)

[Michael Paoli]

At least thus far, the (not yet released)
Debian bullseye 11 (currently also testing)
also offers finit-sysv and finit
But alas, looks not yet ready for prime time:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=983389
Alas, doesn't look very popular:
https://qa.debian.org/popcon.php?package=finit
... well, maybe because installing it and actually booting and running
its init system ... yeah, there is that.
So, for more practical terms, looks like:
systemd
sysvinit
runit

Also, Debian (both Buster 10 (stable) and Bullseye 11 (testing))
have openrc ... but as packaged by Debian, looks to be service manager,
and not init system itself - as it doesn't provide/configure
/sbin/init however openrc Suggests: sysvinit-core which provides
/sbin/init ... so at quick glance would appear openrc is services
manager that runs atop lower-level actual init system.  Things may be
different in Devuan ... or maybe not, in that regard, and maybe
Devaun just describes it differently in the Devuan installer.

As for Devuan,
looks like it currently offers 3 init systems:
sysvinit
openrc
runit
https://www.devuan.org/os/documentation/install-guides/beowulf/install-devuan

Anyway, maybe I'll poke around at 'em some more.

> From: "Michael Paoli" <Michael.Paoli at cal.berkeley.edu>
> Subject: Debian - and NOT systemd! :-)
> Date: Thu, 10 Dec 2020 17:17:04 -0800

> Debian - and NOT systemd! :-)
>
> Far too often I hear/see folks saying stuff like:
> "I hate systemd, Debian uses systemd, I hate Debian, I won't use
> Debian."
> And even highly untrue stuff such as:
> "Debian at this moment you cannot replace init system" ...
> "it is the-only init system." ... "Debian that inits are executed as an
> addition to systemd(you simply cannot get rid of systemd"
>
> It gets quite annoying, really it does.
> Yes, sure, Debian's default init system has been systemd since the
> Debian GNU/Linux 8 "Jessie" released 2015-04-25,
> however Debian continues to make available and support other
> init systems.  E.g. in the current stable,
> Debian GNU/Linux 10 (buster), released 2019-07-06,
> Debian offers and supports 3:
> systemd
> sysvinit
> runit
> Folks also complain about how "difficult" it is to change.
> Well, I call bull on that!
>
> E.g., below I show a Debian host,
> at the moment running systemd.
> Watch how easily and quickly I change from systemd, to runit, then to
> sysvinit, and then back to systemd again:
>
> TZ=GMT0 script -c 'sudo virsh start small.9to10 --console'  
> --timing="$HOME"/tmp/bullscript.time ~/tmp/bullscript
> Script started on 2020-12-10 23:27:48+00:00 [TERM="screen"  
> TTY="/dev/pts/20" COLUMNS="80" LINES="24"]
>
> debian login: root
> Password:
> # echo $(uname -s -r -v -m -o; cat /etc/debian_version); ls -l  
> /proc/1/exe; dpkg -S /sbin/init
> Linux 4.19.0-13-amd64 #1 SMP Debian 4.19.160-2 (2020-11-28) x86_64  
> GNU/Linux 10.7
> lrwxrwxrwx 1 root root 0 Dec 10 23:27 /proc/1/exe -> /lib/systemd/systemd
> systemd-sysv: /sbin/init
> # apt-get -y --allow-change-held-packages install runit-init  
> sysvinit-core- systemd-sysv-
> # cd / && sync && sync && reboot -f -f
>
> debian login: root
> Password:
> # echo $(uname -s -r -v -m -o; cat /etc/debian_version); ls -l  
> /proc/1/exe; dpkg -S /sbin/init
> Linux 4.19.0-13-amd64 #1 SMP Debian 4.19.160-2 (2020-11-28) x86_64  
> GNU/Linux 10.7
> lrwxrwxrwx 1 root root 0 Dec 10 23:31 /proc/1/exe -> /sbin/runit
> runit-init: /sbin/init
> # apt-get -y --allow-change-held-packages install sysvinit-core  
> systemd-sysv- runit-init-
> # cd / && sync && sync && reboot -f -f
>
> debian login: root
> Password:
> # echo $(uname -s -r -v -m -o; cat /etc/debian_version); ls -l  
> /proc/1/exe; dpkg -S /sbin/init
> Linux 4.19.0-13-amd64 #1 SMP Debian 4.19.160-2 (2020-11-28) x86_64  
> GNU/Linux 10.7
> lrwxrwxrwx 1 root root 0 Dec 10 23:36 /proc/1/exe -> /sbin/init
> sysvinit-core: /sbin/init
> # apt-get -y --allow-change-held-packages install systemd-sysv  
> runit-init- sysvinit-core-
> # cd / && sync && sync && reboot -f -f
>
> debian login: root
> Password:
> # echo $(uname -s -r -v -m -o; cat /etc/debian_version); ls -l  
> /proc/1/exe; dpkg -S /sbin/init
> Linux 4.19.0-13-amd64 #1 SMP Debian 4.19.160-2 (2020-11-28) x86_64  
> GNU/Linux 10.7
> lrwxrwxrwx 1 root root 0 Dec 10 23:38 /proc/1/exe -> /lib/systemd/systemd
> systemd-sysv: /sbin/init
> # cd / && shutdown -h now
>
> Script done on 2020-12-10 23:39:02+00:00 [COMMAND_EXIT_CODE="0"]
>
> Want to watch it in replay in real time (or faster or slower)?
> scriptreplay(1)
> tar(1)
> bzip2(1)
> while it lasts:
> http://www.mpaoli.net/~michael/tmp/bullscript.tar.bz2
> $ echo 'exec >>/dev/null 2>&1; cd /home/m/michael/public_html/tmp &&  
> find bullscript.tar.bz2 -type d -prune -o -type f -mtime +90 -exec  
> rm -f \{\} \;; :' | (cd / && TZ=GMT0 at now + 95 days)
> warning: commands will be executed using /bin/sh
> job 62 at Mon Mar 15 23:59:00 2021