# systemctl status unifi
● unifi.service - unifi
   Loaded: loaded (/lib/systemd/system/unifi.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2017-03-27 10:19:12 EDT; 4s ago
  Process: 1647 ExecStart=/usr/lib/unifi/bin/unifi.init start (code=exited, status=0/SUCCESS)
 Main PID: 1773 (jsvc)
   CGroup: /system.slice/unifi.service
           ├─1773 unifi -home /usr/lib/jvm/java-8-openjdk-amd64 -cp /usr/share/java/commons-daemon.jar:/usr/lib/unifi/lib/ace.jar -pidfi
           ├─1774 unifi -home /usr/lib/jvm/java-8-openjdk-amd64 -cp /usr/share/java/commons-daemon.jar:/usr/lib/unifi/lib/ace.jar -pidfi
           ├─1776 unifi -home /usr/lib/jvm/java-8-openjdk-amd64 -cp /usr/share/java/commons-daemon.jar:/usr/lib/unifi/lib/ace.jar -pidfi
           ├─1798 /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java -Xmx1024M -XX:ErrorFile=/usr/lib/unifi/data/logs/hs_err_pid<pid>.log -D
           └─1822 bin/mongod --dbpath /usr/lib/unifi/data/db --port 27117 --logappend --logpath logs/mongod.log --nohttpinterface --bind

Mar 27 10:19:11 nitrogen systemd[1]: Starting unifi...
Mar 27 10:19:11 nitrogen unifi.init[1647]:  * Starting Ubiquiti UniFi Controller unifi
Mar 27 10:19:12 nitrogen unifi.init[1647]:    ...done.
Mar 27 10:19:12 nitrogen systemd[1]: Started unifi.


root@nitrogen:~# echo $JAVA_HOME
/usr/lib/jvm/java-8-oracle/jre/bin/java

root@nitrogen:~# update-alternatives --config java
There are 2 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                            Priority   Status
------------------------------------------------------------
* 0            /usr/lib/jvm/java-8-oracle/jre/bin/java          1081      auto mode
  1            /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java   1081      manual mode
  2            /usr/lib/jvm/java-8-oracle/jre/bin/java          1081      manual mode

Press <enter> to keep the current choice[*], or type selection number: