почему это происходит

Процесс jabber-сервера умирает по собственной инициативе.

и можно ли запретить ему отключаться?

Нет, нельзя запретить процессам падать :)

А вообще, телепатов нет. Вывод systemctl status <имя юнита>, systemctl cat <имя юнита> и journalctl -b -u <имя юнита> в студию.

● openfire.service - LSB: Start/stop openfire jabber server Loaded: loaded (/etc/init.d/openfire; generated) Active: active (exited) since Wed 2020-08-05 12:39:58 UTC; 41min ago Docs: man:systemd-sysv-generator(8) Process: 9737 ExecStart=/etc/init.d/openfire start (code=exited, status=0/SUCCESS)

Aug 05 12:39:58 ubuntu systemd[1]: Starting LSB: Start/stop openfire jabber server… Aug 05 12:39:58 ubuntu openfire[9737]: best java alternative in: Aug 05 12:39:58 ubuntu openfire[9737]: Starting openfire: openfire. Aug 05 12:39:58 ubuntu systemd[1]: Started LSB: Start/stop openfire jabber server.

/run/systemd/generator.late/openfire.service

Automatically generated by systemd-sysv-generator

[Unit] Documentation=man:systemd-sysv-generator(8) SourcePath=/etc/init.d/openfire Description=LSB: Start/stop openfire jabber server Before=multi-user.target Before=multi-user.target Before=multi-user.target Before=graphical.target After=remote-fs.target After=network-online.target Wants=network-online.target

[Service] Type=forking Restart=no TimeoutSec=5min IgnoreSIGPIPE=no KillMode=process GuessMainPID=no RemainAfterExit=yes SuccessExitStatus=5 6 ExecStart=/etc/init.d/openfire start ExecStop=/etc/init.d/openfire stop – Logs begin at Tue 2019-12-03 17:03:14 UTC, end at Wed 2020-08-05 13:22:07 UTC. – Aug 04 15:34:29 ubuntu systemd[1]: Starting LSB: Start/stop openfire jabber server… Aug 04 15:34:30 ubuntu openfire[1447]: best java alternative in: Aug 04 15:34:30 ubuntu openfire[1447]: Starting openfire: openfire. Aug 04 15:34:30 ubuntu systemd[1]: Started LSB: Start/stop openfire jabber server. Aug 05 04:24:57 ubuntu systemd[1]: Stopping LSB: Start/stop openfire jabber server… Aug 05 04:24:57 ubuntu openfire[7097]: best java alternative in: Aug 05 04:24:57 ubuntu openfire[7097]: Stopping openfire: openfire. Aug 05 04:24:57 ubuntu systemd[1]: openfire.service: Succeeded. Aug 05 04:24:57 ubuntu systemd[1]: Stopped LSB: Start/stop openfire jabber server. Aug 05 04:24:57 ubuntu systemd[1]: Starting LSB: Start/stop openfire jabber server… Aug 05 04:24:57 ubuntu openfire[7105]: best java alternative in: Aug 05 04:24:57 ubuntu openfire[7105]: Starting openfire: openfire. Aug 05 04:24:57 ubuntu systemd[1]: Started LSB: Start/stop openfire jabber server. Aug 05 12:39:58 ubuntu systemd[1]: Stopping LSB: Start/stop openfire jabber server… Aug 05 12:39:58 ubuntu openfire[9730]: best java alternative in: Aug 05 12:39:58 ubuntu openfire[9730]: Stopping openfire: openfire. Aug 05 12:39:58 ubuntu systemd[1]: openfire.service: Succeeded. Aug 05 12:39:58 ubuntu systemd[1]: Stopped LSB: Start/stop openfire jabber server. Aug 05 12:39:58 ubuntu systemd[1]: Starting LSB: Start/stop openfire jabber server… Aug 05 12:39:58 ubuntu openfire[9737]: best java alternative in: Aug 05 12:39:58 ubuntu openfire[9737]: Starting openfire: openfire. Aug 05 12:39:58 ubuntu systemd[1]: Started LSB: Start/stop openfire jabber server.

А теперь с разметкой, пожалуйста: Правила разметки (Markdown)

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