mjhjmtu

So, I've also switched from Debian to the Devuan pseudo-fork. But - this doesn't get rid of systemd... I've followed the instructions here, and did:

# apt-get install sysvinit-core sysvinit-utils

but when I then tried:

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

I got basically the following error message:

systemd is the active init system, please switch to another before removing systemd.

Yeah great, just what I thought I was trying to do..

You have to reboot your machine after executing first command.

Please take a look at How to remove systemd from a Debian jessie/sid installation.

1. error reason

this error came from here:

/var/lib/dpkg/info/systemd.prerm

# Prevent systemd from being removed if it's the active init. That
# will not work.
#

if [ "$1" = "remove" ] && [ -e /sys/fs/cgroup/systemd ]; then
 echo "systemd is the active init system, please switch to another before removing systemd."
 exit 1
fi

2. resolve & remove

see systemd cgroup mounts (mounted by /lib/systemd/systemd)

mount
...
tmpfs on /sys/fs/cgroup type tmpfs (rw,nosuid,nodev,noexec,relatime,seclabel,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd)
cgroup on /sys/fs/cgroup/debug type cgroup (rw,nosuid,nodev,noexec,relatime,debug)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)

umount them, and try to remove again:

apt-get remove systemd

OR

apt-get purge systemd

that's worked for me.

3. after remove

then other service manager maybe needed,
sysvinit or upstart or something else.