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+<?xml version='1.0'?>
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" >
+<!-- SPDX-License-Identifier: LGPL-2.1+ -->
+
+<refentry id="org.freedesktop.login1" conditional='ENABLE_LOGIND'
+    xmlns:xi="http://www.w3.org/2001/XInclude">
+  <refentryinfo>
+    <title>org.freedesktop.login1</title>
+    <productname>systemd</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>org.freedesktop.login1</refentrytitle>
+    <manvolnum>5</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>org.freedesktop.login1</refname>
+    <refpurpose>The D-Bus interface of systemd-logind</refpurpose>
+  </refnamediv>
+
+  <refsect1>
+    <title>Introduction</title>
+
+    <para><citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+    is a system service that keeps track of user logins and seats in various ways.</para>
+
+    <para>The daemon provides both a C library interface as well as a D-Bus interface. The library interface
+    may be used to introspect and watch the state of user logins and seats. The bus interface provides the
+    same, but in addition may also be used to make changes to system state. For more information please
+    consult <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+    </para>
+  </refsect1>
+
+  <refsect1>
+    <title>The Manager Object</title>
+
+    <para>The service exposes the following interfaces on the Manager object on the bus:</para>
+
+    <programlisting>
+$ gdbus introspect --system \
+        --dest org.freedesktop.login1 \
+        --object-path /org/freedesktop/login1
+node /org/freedesktop/login1 {
+  interface org.freedesktop.login1.Manager {
+    methods:
+      GetSession(in  s session_id,
+                 out o object_path);
+      GetSessionByPID(in  u pid,
+                      out o object_path);
+      GetUser(in  u uid,
+              out o object_path);
+      GetUserByPID(in  u pid,
+                   out o object_path);
+      GetSeat(in  s seat_id,
+              out o object_path);
+      ListSessions(out a(susso) session_list);
+      ListUsers(out a(uso) user_list);
+      ListSeats(out a(so) seat_list);
+      ListInhibitors(out a(ssssuu) inhibitor_list);
+      CreateSession(in  u uid,
+                    in  u pid,
+                    in  s service,
+                    in  s type,
+                    in  s class,
+                    in  s desktop,
+                    in  s seat_id,
+                    in  u vtnr,
+                    in  s tty,
+                    in  s display,
+                    in  b remote,
+                    in  s remote_user,
+                    in  s remote_host,
+                    in  a(sv) properties,
+                    out s session_id,
+                    out o object_path,
+                    out s runtime_path,
+                    out h fifo_fd,
+                    out u uid,
+                    out s seat_id,
+                    out u vtnr,
+                    out b existing);
+      ReleaseSession(in  s session_id);
+      ActivateSession(in  s session_id);
+      ActivateSessionOnSeat(in  s session_id,
+                            in  s seat_id);
+      LockSession(in  s session_id);
+      UnlockSession(in  s session_id);
+      LockSessions();
+      UnlockSessions();
+      KillSession(in  s session_id,
+                  in  s who,
+                  in  i signo);
+      KillUser(in  u uid,
+               in  i signo);
+      TerminateSession(in  s session_id);
+      TerminateUser(in  u uid);
+      TerminateSeat(in  s seat_id);
+      SetUserLinger(in  u uid,
+                    in  b linger,
+                    in  b interactive);
+      AttachDevice(in  s seat_id,
+                   in  s sysfs,
+                   in  b interactive);
+      FlushDevices(in  b interactive);
+      PowerOff(in  b interactive);
+      Reboot(in  b interactive);
+      Suspend(in  b interactive);
+      Hibernate(in  b interactive);
+      HybridSleep(in  b interactive);
+      CanPowerOff(out s result);
+      CanReboot(out s result);
+      CanSuspend(out s result);
+      CanHibernate(out s result);
+      CanHybridSleep(out s result);
+      ScheduleShutdown(in  s type,
+                       in  t usec);
+      CancelScheduledShutdown(out b cancelled);
+      Inhibit(in  s what,
+              in  s who,
+              in  s why,
+              in  s mode,
+              out h pipe_fd);
+      CanRebootToFirmwareSetup(out s result);
+      SetRebootToFirmwareSetup(in  b enable);
+      SetWallMessage(in  s wall_message,
+                     in  b enable);
+    signals:
+      SessionNew(s session_id,
+                 o object_path);
+      SessionRemoved(s session_id,
+                     o object_path);
+      UserNew(u uid,
+              o object_path);
+      UserRemoved(u uid,
+                  o object_path);
+      SeatNew(s seat_id,
+              o object_path);
+      SeatRemoved(s seat_id,
+                  o object_path);
+      PrepareForShutdown(b start);
+      PrepareForSleep(b start);
+    properties:
+      readwrite b EnableWallMessages = false;
+      readwrite s WallMessage = '';
+      readonly u NAutoVTs = 6;
+      readonly as KillOnlyUsers = [];
+      readonly as KillExcludeUsers = ['root'];
+      readonly b KillUserProcesses = false;
+      readonly b RebootToFirmwareSetup = false;
+      readonly b IdleHint = false;
+      readonly t IdleSinceHint = 0;
+      readonly t IdleSinceHintMonotonic = 0;
+      readonly s BlockInhibited = 'handle-power-key:handle-suspend-key:handle-hibernate-key';
+      readonly s DelayInhibited = 'sleep';
+      readonly t InhibitDelayMaxUSec = 5000000;
+      readonly s HandlePowerKey = 'poweroff';
+      readonly s HandleSuspendKey = 'suspend';
+      readonly s HandleHibernateKey = 'hibernate';
+      readonly s HandleLidSwitch = 'suspend';
+      readonly s HandleLidSwitchDocked = 'ignore';
+      readonly t HoldoffTimeoutUSec = 30000000;
+      readonly s IdleAction = 'ignore';
+      readonly t IdleActionUSec = 1800000000;
+      readonly b PreparingForShutdown = false;
+      readonly b PreparingForSleep = false;
+      readonly (st) ScheduledShutdown = ('', 0);
+      readonly b Docked = false;
+  };
+  interface org.freedesktop.DBus.Peer {
+  };
+  interface org.freedesktop.DBus.Introspectable {
+  };
+  interface org.freedesktop.DBus.Properties {
+  };
+};
+    </programlisting>
+
+    <refsect2>
+      <title>Security</title>
+
+      <para>A number of operations are protected via the PolicyKit privilege
+      system. <function>SetUserLinger()</function> requires the
+      <interfacename>org.freedesktop.login1.set-user-linger</interfacename>
+      privilege. <function>AttachDevice()</function> requires
+      <interfacename>org.freedesktop.login1.attach-device</interfacename> and
+      <function>FlushDevices()</function>
+      <interfacename>org.freedesktop.login1.flush-devices</interfacename>. <function>PowerOff()</function>,
+      <function>Reboot()</function>, <function>Suspend()</function>, <function>Hibernate()</function>,
+      <function>HybridSleep()</function> require
+      <interfacename>org.freedesktop.login1.power-off</interfacename>,
+      <interfacename>org.freedesktop.login1.power-off-multiple-sessions</interfacename>,
+      <interfacename>org.freedesktop.login1.power-off-ignore-inhibit</interfacename>,
+      <interfacename>org.freedesktop.login1.reboot</interfacename>,
+      <interfacename>org.freedesktop.login1.reboot-multiple-sessions</interfacename>,
+      <interfacename>org.freedesktop.login1.reboot-ignore-inhibit</interfacename>,
+      <interfacename>org.freedesktop.login1.suspend</interfacename>,
+      <interfacename>org.freedesktop.login1.suspend-multiple-sessions</interfacename>,
+      <interfacename>org.freedesktop.login1.suspend-ignore-inhibit</interfacename>,
+      <interfacename>org.freedesktop.login1.hibernate</interfacename>,
+      <interfacename>org.freedesktop.login1.hibernate-multiple-sessions</interfacename>,
+      respectively.
+      <interfacename>org.freedesktop.login1.hibernate-ignore-inhibit</interfacename>, depending whether
+      there are other sessions around or active inhibits. <function>Inhibit()</function> is protected via
+      either one of <interfacename>org.freedesktop.login1.inhibit-block-shutdown</interfacename>,
+      <interfacename>org.freedesktop.login1.inhibit-delay-shutdown</interfacename>,
+      <interfacename>org.freedesktop.login1.inhibit-block-sleep</interfacename>,
+      <interfacename>org.freedesktop.login1.inhibit-delay-sleep</interfacename>,
+      <interfacename>org.freedesktop.login1.inhibit-block-idle</interfacename>,
+      <interfacename>org.freedesktop.login1.inhibit-handle-power-key</interfacename>,
+      <interfacename>org.freedesktop.login1.inhibit-handle-suspend-key</interfacename>,
+      <interfacename>org.freedesktop.login1.inhibit-handle-hibernate-key</interfacename>,
+      <interfacename>org.freedesktop.login1.inhibit-handle-lid-switch</interfacename> depending on the lock
+      type and mode taken.</para>
+
+      <para>The <varname>user_interaction</varname> boolean parameters can be used to control whether
+      PolicyKit should interactively ask the user for authentication credentials if it needs to.</para>
+    </refsect2>
+
+    <refsect2>
+      <title>Methods</title>
+
+      <para><function>GetSession()</function> may be used to get the session object path for the session with
+      the specified ID. Similarly, <function>GetUser()</function> and <function>GetSeat()</function> get the
+      user and seat objects, respectively. <function>GetSessionByPID()</function> and
+      <function>GetUserByPID()</function> get the session/user object the specified PID belongs to if there
+      is any.</para>
+
+      <para><function>ListSessions()</function> returns an array with all current sessions. The structures in
+      the array consist of the following fields: session id, user id, user name, seat id, session object
+      path. If a session does not have a seat attached the seat id field will be an empty string.</para>
+
+      <para><function>ListUsers()</function> returns an array with all currently logged in users. The
+      structures in the array consist of the following fields: user id, user name, user object path.</para>
+
+      <para><function>ListSeats()</function> returns an array with all currently available seats. The
+      structure in the array consists of the following fields: seat id, seat object path.</para>
+
+      <para><function>CreateSession()</function> and <function>ReleaseSession()</function> may be used to
+      open or close login sessions. These calls should <emphasis>never</emphasis> be invoked directly by
+      clients. Creating/closing sessions is exclusively the job of PAM and its
+      <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+      module.</para>
+
+      <para><function>ActivateSession()</function> brings the session with the specified ID into the
+      foreground. <function>ActivateSessionOnSeat()</function> does the same, but only if the seat id
+      matches.</para>
+
+      <para><function>LockSession()</function> asks the session with the specified ID to activate the screen
+      lock. <function>UnlockSession()</function> asks the session with the specified ID to remove an active
+      screen lock, if there is any. This is implemented by sending out the Lock() and Unlock() signals from
+      the respective session object which session managers are supposed to listen on.</para>
+
+      <para><function>LockSessions()</function> asks all sessions to activate the screen locks. This may be
+      used to lock any access to the machine in one action. Similarly, <function>UnlockSessions()</function>
+      asks all sessions to deactivate their screen locks.</para>
+
+      <para><function>KillSession()</function> may be used to send a Unix signal to one or all processes of a
+      session. As arguments it takes the session id, either the string <literal>leader</literal> or
+      <literal>all</literal> and a signal number. If <literal>leader</literal> is passed only the session
+      <literal>leader</literal> is killed. If <literal>all</literal> is passed all processes of the session
+      are killed.</para>
+
+      <para><function>KillUser()</function> may be used to send a Unix signal to all processes of a user. As
+      argument it takes the user id and a signal number.</para>
+
+      <para><function>TerminateSession()</function>, <function>TerminateUser()</function>,
+      <function>TerminateSeat()</function> may be used to forcibly terminate one specific session, all
+      processes of a user, and all sessions attached to a specific seat, respectively. The session, user,
+      and seat are identified by their respective IDs.</para>
+
+      <para><function>SetUserLinger()</function> enables or disables user lingering. If enabled the runtime
+      directory of a user is kept around and he may continue to run processes while he is logged out. If
+      disabled the runtime directory goes away as soon as he logs out. Expects three arguments: the UID, a
+      boolean whether to enable/disable and a boolean controlling the PolicyKit authorization interactivity
+      (see above). Note that the user linger state is persistently stored on disk.</para>
+
+      <para><function>AttachDevice()</function> may be used to assign a specific device to a specific
+      seat. The device is identified by its /sys path, and must be eligible for seat assignments. Takes three
+      arguments: the seat id, the sysfs path, and a boolean for controlling PolicyKit interactivity (see
+      above). Device assignments are persistently stored to disk. To create a new seat, simply specify a
+      previously unused seat id. For more information about the seat assignment logic see
+      <ulink url="https://www.freedesktop.org/wiki/Software/systemd/multiseat">Multi-Seat for Linux</ulink>.
+      </para>
+
+      <para><function>FlushDevices()</function> removes all explicit seat assignments for devices, resetting
+      all assignments to the automatic defaults. The only argument this takes is the PolicyKit interactivity
+      boolean (see above).</para>
+
+      <para><function>PowerOff()</function>, <function>Reboot()</function>, <function>Suspend()</function>,
+      <function>Hibernate()</function>, <function>HybridSleep()</function> results in the system being
+      powered off, rebooted, suspend, hibernated or hibernated+suspended. The only argument is the PolicyKit
+      interactivity boolean (see above). The main purpose of these calls is that they enforce PolicyKit
+      policy and hence allow powering off/rebooting/suspending/hibernating even by unprivileged users. They
+      also enforce inhibition locks. UIs should expose these calls as primary mechanism to
+      poweroff/reboot/suspend/hibernate/hybrid-sleep the machine.</para>
+
+      <para><function>CanPowerOff()</function>, <function>CanReboot()</function>,
+      <function>CanSuspend()</function>, <function>CanHibernate()</function>,
+      <function>CanHybridSleep()</function> tests whether the system supports the respective operation and
+      whether the calling user is eligible for the desired operation. Returns one of <literal>na</literal>,
+      <literal>yes</literal>, <literal>no</literal> or <literal>challenge</literal>. If <literal>na</literal>
+      is returned the operation is not available because hardware, kernel or drivers do not support it. If
+      <literal>yes</literal> is returned the operation is supported and the user may execute the operation
+      without further authentication. If <literal>no</literal> is returned the operation is available but the
+      user is not allowed to execute the operation. If <literal>challenge</literal> is returned the operation
+      is available, but only after authorization.</para>
+
+      <para><function>Inhibit()</function> creates an inhibition lock. It takes four parameters:
+      <varname>What</varname>, <varname>Who</varname>, <varname>Why</varname>, and
+      <varname>Mode</varname>. <varname>What</varname> is one or more of <literal>shutdown</literal>,
+      <literal>sleep</literal>, <literal>idle</literal>, <literal>handle-power-key</literal>,
+      <literal>handle-suspend-key</literal>, <literal>handle-hibernate-key</literal>,
+      <literal>handle-lid-switch</literal>, separated by colons, for inhibiting poweroff/reboot,
+      suspend/hibernate, the automatic idle logic, or hardware key handling. <varname>Who</varname> should be
+      a short human readable string identifying the application taking the lock. <varname>Why</varname>
+      should be a short human readable string identifying the reason why the lock is taken. Finally,
+      <varname>Mode</varname> is either <literal>block</literal> or <literal>delay</literal> which encodes
+      whether the inhibit shall be consider mandatory or whether it should just delay the operation to a
+      certain maximum time. The call returns a file descriptor. The lock is released the moment this file
+      descriptor (and all its duplicates) are closed. For more information on the inhibition logic see
+      <ulink url="http://www.freedesktop.org/wiki/Software/systemd/inhibit">Inhibitor Locks</ulink>.
+      </para>
+
+      <para><function>ListInhibitors()</function> lists all currently active inhibitors. Returns an array of
+      structures consisting of what, who, why, mode, user ID and process ID.</para>
+    </refsect2>
+
+    <refsect2>
+      <title>Signals</title>
+
+      <para>Whenever the inhibition state or idle hint changes daemon <function>PropertyChanged</function>
+      signals are sent out to which clients can subscribe.</para>
+
+      <para>The <function>SessionNew()</function>, <function>SessionRemoved()</function>,
+      <function>UserNew()</function>, <function>UserRemoved()</function>, <function>SeatNew()</function>,
+      <function>SeatRemoved()</function> signals are sent each time a session is created or removed, a user
+      logs in or out, or a seat is added or removed. They each contain the ID of the object plus the object
+      path.</para>
+
+      <para>The <function>PrepareForShutdown()</function> and <function>PrepareForSleep()</function> signals
+      are sent right before (with the argument <literal>true</literal>) and after (with the argument
+      <literal>false</literal>) the system goes down for reboot/poweroff and suspend/hibernate,
+      respetively. This may be used by applications to save data on disk, release memory, or do other jobs
+      that shall be done shortly before shutdown/sleep, in conjunction with delay inhibitor locks. After
+      completion of this work they should release their inhibition locks in order not to delay the operation
+      any further. For more information see
+      <ulink url="http://www.freedesktop.org/wiki/Software/systemd/inhibit">Inhibitor Locks</ulink>.
+      </para>
+    </refsect2>
+
+    <refsect2>
+      <title>Properties</title>
+
+      <para>Most properties simply reflect the configuration stored in logind.conf. For more information,
+      see
+      <citerefentry><refentrytitle>logind.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+      </para>
+
+      <para>The <function>IdleHint</function> property reflects the idle hint state of the system. If the
+      system is idle it might get into automatic suspend or shutdown, depending on configuration.</para>
+
+      <para><function>IdleSinceHint</function> and <function>IdleSinceHintMonotonic</function> encode the
+      timestamps of the last change of the idle hint boolean, in <constant>CLOCK_REALTIME</constant> and
+      <constant>CLOCK_MONOTONIC</constant> timestamps, respectively, in microseconds since the epoch.</para>
+
+      <para>The <function>BlockInhibited</function> and <function>DelayInhibited</function> properties encode
+      the currently active locks of the respective modes. They are colon separated lists of
+      <literal>shutdown</literal>, <literal>sleep</literal>, <literal>idle</literal> (see above).</para>
+
+      <para>The <function>PreparingForShutdown</function> and <function>PreparingForSleep</function> boolean
+      properties are true between the time when the two <function>PrepareForShutdown</function> and
+      <function>PrepareForSleep</function> signals are sent, respectively. Note that these properties do not
+      send out <function>PropertyChanged</function> signals.</para>
+    </refsect2>
+  </refsect1>
+
+  <refsect1>
+    <title>Seat Objects</title>
+
+    <programlisting>
+$ gdbus introspect --system --dest org.freedesktop.login1 \
+      --object-path /org/freedesktop/login1/seat/seat0
+node /org/freedesktop/login1/seat/seat0 {
+  interface org.freedesktop.login1.Seat {
+    methods:
+      Terminate();
+      ActivateSession(in  s session_id);
+      SwitchTo(in  u vtnr);
+      SwitchToNext();
+      SwitchToPrevious();
+    properties:
+      readonly s Id = 'seat0';
+      readonly (so) ActiveSession = ('', '/');
+      readonly b CanMultiSession = true;
+      readonly b CanTTY = true;
+      readonly b CanGraphical = true;
+      readonly a(so) Sessions = [('c1', '/org/freedesktop/login1/session/c1')];
+      readonly b IdleHint = true;
+      readonly t IdleSinceHint = 1389368976087311;
+      readonly t IdleSinceHintMonotonic = 48213948;
+  };
+  interface org.freedesktop.DBus.Properties {
+  };
+  interface org.freedesktop.DBus.Peer {
+  };
+  interface org.freedesktop.DBus.Introspectable {
+  };
+};
+    </programlisting>
+
+    <refsect2>
+      <title>Methods</title>
+
+      <para><function>Terminate()</function> and <function>ActivateSession()</function> work similar to
+      TerminateSeat(), ActivationSessionOnSeat() on the Manager object.</para>
+    </refsect2>
+
+    <refsect2>
+      <title>Signals</title>
+
+      <para>Whenever <function>ActiveSession</function>, <function>Sessions</function>,
+      <function>CanGraphical</function>, <function>CanMultiSession</function> and <function>CanTTY</function>
+      or the idle state changes <function>PropertyChanged</function> signals are sent out to which clients
+      can subscribe.</para>
+    </refsect2>
+
+    <refsect2>
+      <title>Properties</title>
+
+      <para>The <varname>Id</varname> property encodes the ID of the seat.</para>
+
+      <para><varname>ActiveSession</varname> encodes the currently active session if there is one. It is a
+      structure consisting of session id and object path.</para>
+
+      <para><varname>CanMultiSession</varname> encodes whether the session is multi-session capable, CanTTY
+      whether it is suitable for text logins, CanGraphical whether it is suitable for graphical sessions.</para>
+
+      <para>The <varname>Sessions</varname> array is an array of all current sessions of this seat, each
+      encoded in a structure consisting of the ID and the object path.</para>
+
+      <para>The <varname>IdleHint</varname>, <varname>IdleSinceHint</varname>,
+      <varname>IdleSinceHint</varname> properties encode the idle state, similar to the one exposed on the
+      Manager object, but specific for this seat.</para>
+    </refsect2>
+  </refsect1>
+
+  <refsect1>
+    <title>User Objects</title>
+
+    <programlisting>
+$ gdbus introspect --system --dest org.freedesktop.login1 \
+        --object-path /org/freedesktop/login1/user/_1000
+
+node /org/freedesktop/login1/user/_1000 {
+  interface org.freedesktop.login1.User {
+    methods:
+      Terminate();
+      Kill(in  i signo);
+    properties:
+      readonly u UID = 1000;
+      readonly u GID = 1000;
+      readonly s Name = 'test';
+      readonly t Timestamp = 1389368964102424;
+      readonly t TimestampMonotonic = 36229061;
+      readonly s RuntimePath = '/run/user/1000';
+      readonly s Service = 'user@1000.service';
+      readonly s Slice = 'user-1000.slice';
+      readonly (so) Display = ('', '/');
+      readonly s State = 'active';
+      readonly a(so) Sessions = [('28', '/org/freedesktop/login1/session/_328'), ('3', '/org/freedesktop/login1/session/_33')];
+      readonly b IdleHint = false;
+      readonly t IdleSinceHint = 0;
+      readonly t IdleSinceHintMonotonic = 0;
+      readonly b Linger = false;
+  };
+  interface org.freedesktop.DBus.Properties {
+  };
+  interface org.freedesktop.DBus.Peer {
+  };
+  interface org.freedesktop.DBus.Introspectable {
+  };
+};
+    </programlisting>
+
+    <refsect2>
+      <title>Methods</title>
+
+      <para><function>Terminate()</function> and <function>Kill()</function> work similar to the
+      <function>TerminateUser()</function> and <function>KillUser()</function> calls on the manager
+      object.</para>
+    </refsect2>
+
+    <refsect2>
+      <title>Signals</title>
+
+      <para>Whenever <varname>Sessions</varname> or the idle state changes
+      <function>PropertyChanged</function> signals are sent out to which clients can subscribe.</para>
+    </refsect2>
+
+    <refsect2>
+      <title>Properties</title>
+
+      <para>The <varname>UID</varname> and <varname>GID</varname> properties encode the Unix UID and primary
+      GID of the user.</para>
+
+      <para>The <varname>Name</varname> property encodes the user name.</para>
+
+      <para><varname>Timestamp</varname> and <varname>TimestampMonotonic</varname> encode the login time of
+      the user in usec since the epoch, in the <constant>CLOCK_REALTIME</constant> and
+      <constant>CLOCK_MONOTONIC</constant> clocks, respectively.</para>
+
+      <para><varname>RuntimePath</varname> encodes the runtime path of the user,
+      i.e. <varname>$XDG_RUNTIME_DIR</varname>, for details see the
+      <ulink url="https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html">
+        XDG Basedir Specification
+      </ulink>.</para>
+
+      <para><varname>Service</varname> contains the name of the user systemd service unit name of this
+      user. Each logged in user gets a user service unit assigned that runs a user systemd instance. This is
+      usually an instance of <filename>user@.service</filename>.</para>
+
+      <para><varname>Slice</varname> contains the name of the user systemd slice unit name of this user. Each
+      logged in user gets a private slice.</para>
+
+      <para><varname>Display</varname> encodes which graphical session should be used as primary UI display
+      for the use. It is a structure encoding session ID and object path of the session to use.</para>
+
+      <para><varname>State</varname> encodes the user state, one of <literal>offline</literal>,
+      <literal>lingering</literal>, <literal>online</literal>, <literal>active</literal>,
+      <literal>closing</literal>. See
+      <citerefentry><refentrytitle>sd_uid_get_state</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+      for more information about the states.</para>
+
+      <para><varname>Sessions</varname> is an array of structures encoding all current sessions of the
+      user. Each structure consists of ID and object path.</para>
+
+      <para>The <varname>IdleHint</varname>, <varname>IdleSinceHint</varname>,
+      <varname>IdleSinceHintMonotonic</varname> properties encode the idle hint state of the user, similar to
+      the <interfacename>Manager</interfacename>'s properties, but specific for this user.</para>
+    </refsect2>
+  </refsect1>
+
+  <refsect1>
+    <title>Session Objects</title>
+
+    <programlisting>
+$ gdbus introspect --system --dest org.freedesktop.login1 \
+        --object-path /org/freedesktop/login1/session/3
+
+node /org/freedesktop/login1/session/3 {
+  interface org.freedesktop.login1.Session {
+    methods:
+      Terminate();
+      Activate();
+      Lock();
+      Unlock();
+      SetIdleHint(in  b idle);
+      Kill(in  s who,
+           in  i signo);
+      TakeControl(in  b force);
+      ReleaseControl();
+      TakeDevice(in  u major,
+                 in  u minor,
+                 out h fd,
+                 out b inactive);
+      ReleaseDevice(in  u major,
+                    in  u minor);
+      PauseDeviceComplete(in  u major,
+                          in  u minor);
+    signals:
+      PauseDevice(u major,
+                  u minor,
+                  s type);
+      ResumeDevice(u major,
+                   u minor,
+                   h fd);
+      Lock();
+      Unlock();
+    properties:
+      readonly s Id = '3';
+      readonly (uo) User = (1000, '/org/freedesktop/login1/user/_1000');
+      readonly s Name = 'test';
+      readonly t Timestamp = 1389370644734067;
+      readonly t TimestampMonotonic = 72063381;
+      readonly u VTNr = 0;
+      readonly (so) Seat = ('', '/');
+      readonly s TTY = '';
+      readonly s Display = '';
+      readonly b Remote = true;
+      readonly s RemoteHost = '129.174.150.217';
+      readonly s RemoteUser = '';
+      readonly s Service = 'sshd';
+      readonly s Desktop = '';
+      readonly s Scope = 'session-3.scope';
+      readonly u Leader = 1854;
+      readonly u Audit = 3;
+      readonly s Type = 'tty';
+      readonly s Class = 'user';
+      readonly b Active = true;
+      readonly s State = 'active';
+      readonly b IdleHint = false;
+      readonly t IdleSinceHint = 0;
+      readonly t IdleSinceHintMonotonic = 0;
+  };
+  interface org.freedesktop.DBus.Properties {
+  };
+  interface org.freedesktop.DBus.Peer {
+  };
+  interface org.freedesktop.DBus.Introspectable {
+  };
+};
+    </programlisting>
+
+    <refsect2>
+      <title>Methods</title>
+
+      <para><function>Terminate()</function>, <function>Activate()</function>, <function>Lock()</function>,
+      <function>Unlock()</function>, <function>Kill()</function> work similarly to the respective calls on
+      the <interfacename>Manager</interfacename> object.</para>
+
+      <para><function>SetIdleHint()</function> shall be called by the session object to update the idle state
+      of the session, whenever it changes.</para>
+
+      <para><function>TakeControl()</function> allows a process to take exclusive managed device
+      access-control for that session. Only one dbus-connection can be a controller for a given session at a
+      time. If the <function>force</function> argument is set (root only), an existing controller is kicked
+      out and replaced. Otherwise, this call fails if there is already a controller.  Note that this call is
+      limited to dbus-users with the effective UID set to the User of the Session or root.</para>
+
+      <para><function>ReleaseControl()</function> drops control of a given session again. Closing the
+      dbus-connection implicitly releases control, too. See <function>TakeControl()</function> for more. This
+      also releases all devices for the controller that were requested via <function>TakeDevice()</function>.
+      </para>
+
+      <para><function>TakeDevice()</function> allows a session-controller to get a file-descriptor for a
+      specific device. Pass in the major and minor numbers of the character-device and
+      <filename>systemd-logind</filename> will return a file-descriptor for the device. Only a limited set of
+      device-types is currently supported (but may be extended). <filename>systemd-logind</filename>
+      automatically mutes the file-descriptor if the session is inactive and resumes it once the session gets
+      active again. This guarantees that a session can only access session-devices if the session is
+      active. Note that this revoke/resume mechanism is asynchronous and may happen at any given time.  This
+      only works on devices that are attached to the seat of the given session. A process is not required to
+      have direct access to the device-node. <filename>systemd-logind</filename> only requires you to be the
+      active session controller (see <function>TakeControl()</function>). Also note that any device can only
+      be requested once. As long as you don't release it, further <function>TakeDevice()</function> calls
+      will fail.</para>
+
+      <para><function>ReleaseDevice()</function> releases a device again (see
+      <function>TakeDevice()</function>). This is also implicitly done by
+      <function>ReleaseControl()</function> or when closing the dbus-connection.</para>
+
+      <para><function>PauseDeviceComplete()</function> allows a session-controller to synchronously pause a
+      device after receiving a <function>PauseDevice(<literal>pause</literal>)</function> signal. Forced
+      signals (or after an internal timeout) are automatically completed by
+      <filename>systemd-logind</filename> asynchronously.</para>
+    </refsect2>
+
+    <refsect2>
+      <title>Signals</title>
+
+      <para>The active session-controller exclusively gets <function>PauseDevice</function> and
+      <function>ResumeDevice</function> events for any device it requested via
+      <function>TakeDevice()</function>. They notify the controller whenever a device is paused or resumed. A
+      device is never resumed if a session is inactive. Also note that <function>PauseDevice</function>
+      signals are sent before the <function>PropertyChanged</function> signal for the
+      <function>Active</function> state. The inverse is true for <function>ResumeDevice</function>. A device
+      may remain paused for unknown reasons even though the <interfacename>Session</interfacename> is active.
+      </para>
+
+      <para>A <function>PauseDevice</function> signal carries the major and minor and a string describing the
+      type as arguments. <function>force</function> means the device got paused by
+      <filename>systemd-logind</filename> already and this is only an asynchronous
+      notification. <function>pause</function> means <filename>systemd-logind</filename> tries to pause the
+      device and grants you limited amount of time to pause it. You must respond to this via
+      <function>PauseDeviceComplete()</function>. This synchronous pausing-mechanism is used for
+      backwards-compatibility to VTs and <filename>systemd-logind</filename> is free to not make use of
+      it. It is also free to send a forced <function>PauseDevice</function> if you don't respond in a timely
+      manner (or for any other reason). <function>gone</function> means the device was unplugged from the
+      system and you will no longer get any notifications about it. There is no reason to call
+      <function>ReleaseDevice()</function>. You may call <function>TakeDevice()</function> again if a new
+      device gets the major+minor combination assigned.</para>
+
+      <para><function>ResumeDevice</function> is sent whenever a session is active and a device is
+      resumed. It carries the major/minor as arguments and provides a new open file-descriptor. You should
+      switch to the new descriptor and close the old one. They are not guaranteed to have the same underlying
+      open-file-descriptor in the kernel (except for a limited set of device types).</para>
+
+      <para>Whenever <function>Active</function> or the idle state changes
+      <function>PropertyChanged</function> signals are sent out to which clients can subscribe.</para>
+
+      <para><function>Lock</function>/<function>Unlock</function> is sent when the session is asked to be
+      screen-locked/unlocked. A session manager of the session should listen to this signal and act
+      accordingly. This signal is sent out as a result of the <function>Lock()</function> and
+      <function>Unlock()</function> methods, respectively.</para>
+    </refsect2>
+
+    <refsect2>
+      <title>Properties</title>
+
+      <para><varname>Id</varname> encodes the session ID.</para>
+
+      <para><varname>User</varname> encodes the user ID of the user this session belongs to. This is a
+      structure encoding the Unix UID and the object path.</para>
+
+      <para><varname>Name</varname> encodes the user name.</para>
+
+      <para><varname>Timestamp</varname> and <varname>TimestampMonotonic</varname> encode the usec timestamp
+      since the epoch when the session was created, in <constant>CLOCK_REALTIME</constant> or
+      <constant>CLOCK_MONOTONIC</constant>, respectively.</para>
+
+      <para><varname>VTNr</varname> encodes the virtual terminal number of the session if there is any, 0
+      otherwise.</para>
+
+      <para><varname>Seat</varname> encodes the seat this session belongs to, if there is any. This is a
+      structure consisting of the ID and the seat object path.</para>
+
+      <para><varname>TTY</varname> encodes the kernel TTY path of the session if this is a text login. If not
+      this is an empty string.</para>
+
+      <para><varname>Display</varname> encodes the X11 display name if this is a graphical login. If not,
+      this is an empty string.</para>
+
+      <para><varname>Remote</varname> encodes whether the session is local or remote.</para>
+
+      <para><varname>RemoteHost</varname> and <varname>RemoteUser</varname> encode the remote host and user
+      if this is a remote session, or an empty string otherwise.</para>
+
+      <para><varname>Service</varname> encodes the PAM service name that registered the session.</para>
+
+      <para><varname>Scope</varname> contains the systemd scope unit name of this session.</para>
+
+      <para><varname>Leader</varname> encodes the PID of the process that registered the session.</para>
+
+      <para><varname>Audit</varname> encodes the Kernel Audit session ID of the session, if auditing is
+      available.</para>
+
+      <para><varname>Type</varname> encodes the session type. It's one of <literal>unspecified</literal> (for
+      cron PAM sessions and suchlike), <literal>tty</literal> (for text logins) or
+      <literal>x11</literal>/<literal>mir</literal>/<literal>wayland</literal> (for graphical logins).</para>
+
+      <para><varname>Class</varname> encodes the session class. It's one of <literal>user</literal> (for
+      normal user sessions), <literal>greeter</literal> (for display manager pseudo-sessions),
+      <literal>lock-screen</literal> (for display lock screens).</para>
+
+      <para><varname>Active</varname> is a boolean that is true if the session is active, i.e. currently in the
+      foreground. This field is semi-redundant due to State.</para>
+
+      <para><varname>State</varname> encodes the session state and one of <literal>online</literal>,
+      <literal>active</literal>, <literal>closing</literal>. See
+      <citerefentry><refentrytitle>sd_session_get_state</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+      for more information about the states.</para>
+
+      <para><varname>IdleHint</varname>, <varname>IdleSinceHint</varname>,
+      <varname>IdleSinceHintMonotonic</varname> encapsulate the idle hint state of this session, similarly to
+      how the respective properties on the manager object do it for the whole system.</para>
+    </refsect2>
+  </refsect1>
+
+  <refsect1>
+    <title>Versioning</title>
+
+    <para>These D-Bus interfaces follow <ulink url="http://0pointer.de/blog/projects/versioning-dbus.html">
+    the usual interface versioning guidelines</ulink>.</para>
+  </refsect1>
+</refentry>