My I'm not sure which one is used But it's standard Debian Jessie installation.
When I run
sudo systemctl enable btsync
I get this:
Synchronizing state for btsync.service with sysvinit using update-rc.d...
Executing /usr/sbin/update-rc.d btsync defaults
Executing /usr/sbin/update-rc.d btsync enable
Then after restart I run
sudo service btsync status
and get
● btsync.service - BitTorrent Sync service
Loaded: loaded (/lib/systemd/system/btsync.service; enabled)
Active: failed (Result: start-limit) since Tue 2016-04-26 22:49:59 EEST; 1min 41s ago
Docs: http://help.getsync.com/
Process: 1046 ExecStart=/usr/bin/btsync --config /etc/btsync/config.json (code=exited, status=0/SUCCESS)
Process: 1042 ExecStartPre=/bin/chown -R btsync:btsync /var/run/btsync (code=exited, status=0/SUCCESS)
Process: 1041 ExecStartPre=/bin/mkdir -p /var/run/btsync (code=exited, status=0/SUCCESS)
Main PID: 1048 (code=exited, status=255)
Apr 26 22:49:59 serveris systemd[1]: Unit btsync.service entered failed state.
Apr 26 22:49:59 serveris systemd[1]: btsync.service start request repeated too quickly, refusing to start.
Apr 26 22:49:59 serveris systemd[1]: Failed to start BitTorrent Sync service.
Apr 26 22:49:59 serveris systemd[1]: Unit btsync.service entered failed state.
Then I'm able to start it manually:
sudo service btsync start
sudo service btsync status
● btsync.service - BitTorrent Sync service
Loaded: loaded (/lib/systemd/system/btsync.service; enabled)
Active: active (running) since Tue 2016-04-26 22:52:20 EEST; 6s ago
Docs: http://help.getsync.com/
Process: 1485 ExecStart=/usr/bin/btsync --config /etc/btsync/config.json (code=exited, status=0/SUCCESS)
Process: 1482 ExecStartPre=/bin/chown -R btsync:btsync /var/run/btsync (code=exited, status=0/SUCCESS)
Process: 1479 ExecStartPre=/bin/mkdir -p /var/run/btsync (code=exited, status=0/SUCCESS)
Main PID: 1486 (btsync)
CGroup: /system.slice/btsync.service
└─1486 /usr/bin/btsync --config /etc/btsync/config.json