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/*!

 \page neptune3ui-systemd-service-settings.html
 \title Neptune 3 UI - Systemd Service Settings
 \brief Description of settings used to start Neptune 3 UI as a systemd service.

 There are three sections in Neptune 3 UI service file:

 \list
  \li [Unit]
  \li [Service]
  \li [Install]
 \endlist

 \section1 [Unit] Section

 This section describes the service itself, including dependencies and/or conflicts,
 as well as loading order.

 The section consists of a number of variables, as follows:

 \table
  \header
   \li Variable
   \li Description

  \row
   \li Description=Neptune3-UI
   \li Service description displayed by system tools

  \row
   \li After=dbus.service dbus-session@root.service systemd-user-sessions.service ivi-services.target
   \li Loading order (After=dbus.service). It means that Neptune 3 UI systemd Service will be loaded
       after dbus.service. Then goes dbus user session (there are two sessions - user and system session), and
       a number of services providing data for Neptune 3 UI (ivi-services.target).

  \row
   \li Wants=ivi-services.target dbus-session@root.service
   \li Tells that ivi-services.target and dbus user session are in direct dependence.

  \row
   \li Conflicts=neptune-qsr.service
       Before=neptune-qsr.service
       OnFailure=neptune-qsr.service
   \li These variables describe the startup behavior: first, neptune3-ui starts, then it conflicts with
       QSR Content app. Also, those variables mean that QSR content app should start, if neptune3-ui
       crashes. It could be just {conflicts}, but in this case systemd does not wait for
       complete shut down of Neptune 3 UI and shuts down both of the services.
  \endtable

  \section1 [Service] Section

  This section describes, how the service starts up and what parameters are used for that.

  \table
   \header
    \li Variable
    \li Description

   \row
    \li User=root
    \li Start as a root user (administrator in linux/unix).

   \row
    \li ExecStart=/opt/neptune3/neptune3-ui -r --dbus session -c am-config-neptune.yaml
    \li Sevice startup command.

   \row
    \li WorkingDirectory=/opt/neptune3
    \li Catalog, to which systemd switches to before service is started.

   \row
    \li EnvironmentFile=/etc/default/qt
    \li Environment variables are loaded from the file in format \c Variable=value

   \row
    \li Environment=AM_STARTUP_TIMER=1
    \li When set to "1", this variable enables measuring of time needed to
        start up the Neptune 3 UI. In this case, the measured time value is displayed
        in the system menu.
        When set to "0", the measuring of time needed to start up the Neptune 3 UI
        is turned off, and is not displayed in the system menu.

   \row
    \li Environment=QT_QPA_EGLFS_HIDECURSOR=1
    \li This variable manages visibility of mouse cursor: when set to "1" mouse cursor
        is hidden, when set to "0" it is visible.

   \endtable

   \section1 [Install] Section

   In this section it's determined, how the service file will be installed.

  \table
   \header
    \li Variable
    \li Description

   \row
    \li WantedBy=multi-user.target
    \li In this use case the service file is a part of multi-user system target. That's why it
        will be installed as one of dependencies.

   \endtable

   \note In any case of changes in .service file, it's necessary to run \c {systemctl daemon-reload},
         otherwise \c systemd will not reload the file changes and will use the old file.



 */