Resolução
Instale systemd-sysv :
apt install systemd-sysv
Explicação
Failed to get D-Bus connection: Unknown error -1 significa que o systemd não está em execução.
Aqui está a minha instalação do LMDE 2, que é muito parecido com o Debian 8:
lmde ~ # systemctl status ssh.service
Failed to get D-Bus connection: Unknown error -1
No seu sistema, /sbin/init provavelmente não é um link simbólico apontando para /lib/systemd/systemd . Aqui está o que parece no LMDE 2:
lmde ~ # file /sbin/init
/sbin/init: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=416c01d5df07b3a795694ff3360339b509daaf86, stripped
Aqui está o que parece no Ubuntu 16.04 LTS, que executa o systemd por padrão:
root@node51 [~]# file /sbin/init
/sbin/init: symbolic link to /lib/systemd/systemd
Para resolver isso, substitua o pacote sysvinit-core por systemd-sysv :
lmde ~ # apt install systemd-sysv
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
sysvinit-core
The following NEW packages will be installed:
systemd-sysv
0 upgraded, 1 newly installed, 1 to remove and 533 not upgraded.
Need to get 32.7 kB of archives.
After this operation, 177 kB disk space will be freed.
Do you want to continue? [Y/n] Y
Get:1 http://packages.linuxmint.com/ betsy/upstream systemd-sysv amd64 215+12+betsy [32.7 kB]
Fetched 32.7 kB in 0s (81.1 kB/s)
dpkg: sysvinit-core: dependency problems, but removing anyway as you requested:
init depends on systemd-sysv | sysvinit-core | upstart; however:
Package systemd-sysv is not installed.
Package sysvinit-core is to be removed.
Package upstart is not installed.
(Reading database ... 159705 files and directories currently installed.)
Removing sysvinit-core (2.88dsf-58) ...
Processing triggers for man-db (2.7.0.2-5) ...
Selecting previously unselected package systemd-sysv.
(Reading database ... 159681 files and directories currently installed.)
Preparing to unpack .../systemd-sysv_215+12+betsy_amd64.deb ...
Unpacking systemd-sysv (215+12+betsy) ...
Processing triggers for man-db (2.7.0.2-5) ...
Setting up systemd-sysv (215+12+betsy) ...
Agora reinicie com reboot .
Quando o sistema for reinicializado, você estará executando o systemd em vez do SysV:
lmde ~ # file /sbin/init
/sbin/init: symbolic link to /lib/systemd/systemd
lmde ~ # systemctl status ssh.service
● ssh.service - OpenBSD Secure Shell server
Loaded: loaded (/lib/systemd/system/ssh.service; enabled)
Active: active (running) since Wed 2017-02-08 06:58:27 CST; 1min 10s ago
Main PID: 598 (sshd)
CGroup: /system.slice/ssh.service
└─598 /usr/sbin/sshd -D
Feb 08 06:58:27 lmde sshd[598]: Server listening on 0.0.0.0 port 22.
Feb 08 06:58:27 lmde sshd[598]: Server listening on :: port 22.
Feb 08 06:58:29 lmde sshd[598]: Received SIGHUP; restarting.
Feb 08 06:58:29 lmde sshd[598]: Server listening on 0.0.0.0 port 22.
Feb 08 06:58:29 lmde sshd[598]: Server listening on :: port 22.
Feb 08 06:58:44 lmde sshd[1614]: Accepted password for root from 10.0.0.2 port 59703 ssh2
Feb 08 06:58:44 lmde sshd[1614]: pam_unix(sshd:session): session opened for user root by (uid=0)
Possível causa?
Você indicou que o systemd em sua instalação Debian funcionou no passado. É possível que um pacote ou suas dependências precisem do SysVinit em vez do systemd e do systemd apagado ou desabilitado.
Fique atento a dependências quebradas, se for esse o caso.
Recursos adicionais
Documentação
Descrição de sysvinit-core
lmde ~ # apt show sysvinit-core
Package: sysvinit-core
State: not installed
Version: 2.88dsf-59
Priority: extra
Section: admin
Maintainer: Debian sysvinit maintainers <[email protected]>
Architecture: amd64
Uncompressed Size: 199 k
Depends: initscripts (>= 2.88dsf-13.3), sysv-rc | file-rc, sysvinit-utils (>=
2.86.ds1-66), libc6 (>= 2.15), libselinux1 (>= 1.32), libsepol1 (>=
1.14), debconf (>= 0.5) | debconf-2.0, debianutils (>= 4)
Conflicts: systemd-sysv, systemd-sysv, upstart, upstart, sysvinit-core
Replaces: systemd-sysv, systemd-sysv, sysvinit (< 2.88dsf-44~), sysvinit (<
2.88dsf-44~), upstart, upstart
Description: System-V-like init utilities
This package contains programs required for booting a Debian system and doing
basic process management.
The most important program in the package is /sbin/init. It is the first
process started on boot and continues to run as process number 1 until the
system halts. All other processes are descended from it.
Homepage: http://savannah.nongnu.org/projects/sysvinit
Descrição de systemd-sysv
lmde ~ # apt show systemd-sysv
Package: systemd-sysv
State: installed
Automatically installed: no
Version: 215+12+betsy
Priority: extra
Section: admin
Maintainer: Debian systemd Maintainers <[email protected]>
Architecture: amd64
Uncompressed Size: 77.8 k
Depends: systemd (= 215+12+betsy)
PreDepends: systemd
Conflicts: sysvinit-core, sysvinit-core, upstart, upstart, systemd-sysv
Replaces: sysvinit (< 2.88dsf-44~), sysvinit (< 2.88dsf-44~), sysvinit-core,
sysvinit-core, upstart, upstart
Description: system and service manager - SysV links
systemd is a replacement for sysvinit. It is dependency-based and able to read
the LSB init script headers in addition to parsing rcN.d links as hints.
It also provides process supervision using cgroups and the ability to not only
depend on other init script being started, but also availability of a given
mount point or dbus service.
This package provides the manual pages and links needed for systemd to replace
sysvinit. Installing systemd-sysv will overwrite /sbin/init with a link to
systemd.
Homepage: http://www.freedesktop.org/wiki/Software/systemd