NAME

       org.freedesktop.timedate1 - The D-Bus interface of systemd-timedated

INTRODUCTION

       systemd-timedated.service(8) is a system service that can be used to control the system time and related
       settings. This page describes the D-Bus interface.

THE D-BUS API

       The service exposes the following interfaces on the bus:

           node /org/freedesktop/timedate1 {
             interface org.freedesktop.timedate1 {
               methods:
                 SetTime(in  x usec_utc,
                         in  b relative,
                         in  b interactive);
                 SetTimezone(in  s timezone,
                             in  b interactive);
                 SetLocalRTC(in  b local_rtc,
                             in  b fix_system,
                             in  b interactive);
                 SetNTP(in  b use_ntp,
                        in  b interactive);
                 ListTimezones(out as timezones);
               properties:
                 readonly s Timezone = '...';
                 readonly b LocalRTC = ...;
                 @org.freedesktop.DBus.Property.EmitsChangedSignal("false")
                 readonly b CanNTP = ...;
                 readonly b NTP = ...;
                 @org.freedesktop.DBus.Property.EmitsChangedSignal("false")
                 readonly b NTPSynchronized = ...;
                 @org.freedesktop.DBus.Property.EmitsChangedSignal("false")
                 readonly t TimeUSec = ...;
                 @org.freedesktop.DBus.Property.EmitsChangedSignal("false")
                 readonly t RTCTimeUSec = ...;
             };
             interface org.freedesktop.DBus.Peer { ... };
             interface org.freedesktop.DBus.Introspectable { ... };
             interface org.freedesktop.DBus.Properties { ... };
           };

   Methods
       Use SetTime() to change the system clock. Pass a value of microseconds since the UNIX epoch (1 Jan 1970
       UTC). If relative is true, the passed usec value will be added to the current system time. If it is
       false, the current system time will be set to the passed usec value. If the system time is set with this
       method, the RTC will be updated as well.

       Use SetTimezone() to set the system timezone. Pass a value like "Europe/Berlin" to set the timezone.
       Valid timezones are listed in /usr/share/zoneinfo/zone.tab. If the RTC is configured to be maintained in
       local time, it will be updated accordingly.

       Use SetLocalRTC() to control whether the RTC is in local time or UTC. It is strongly recommended to
       maintain the RTC in UTC. However, some OSes (Windows) maintain the RTC in local time, which might make it
       necessary to enable this feature. Note that this might create various problems as daylight changes could
       be missed. If fix_system is "true", the time from the RTC is read again and the system clock is adjusted
       according to the new setting. If fix_system is "false", the system time is written to the RTC taking the
       new setting into account. Use fix_system=true in installers and livecds where the RTC is probably more
       reliable than the system time. Use fix_system=false in configuration UIs that are run during normal
       operation and where the system clock is probably more reliable than the RTC.

       Use SetNTP() to control whether the system clock is synchronized with the network using
       systemd-timesyncd. This will enable and start or disable and stop the chosen time synchronization
       service.

       ListTimezones() returns a list of time zones known on the local system as an array of names
       ("["Africa/Abidjan", "Africa/Accra", ..., "UTC"]").

   Properties
       Timezone shows the currently configured time zone.  LocalRTC shows whether the RTC is configured to use
       UTC (false), or the local time zone (true).  CanNTP shows whether a service to perform time
       synchronization over the network is available, and NTP shows whether such a service is enabled.

       NTPSynchronized shows whether the kernel reports the time as synchronized (c.f.  adjtimex(3)).  TimeUSec
       and RTCTimeUSec show the current time on the system and in the RTC. The purpose of those three properties
       is to allow remote clients to access this information over D-Bus. Local clients can access the
       information directly.

       Whenever the Timezone and LocalRTC settings are changed via the daemon, PropertyChanged signals are sent
       out to which clients can subscribe.

       Note that this service will not inform you about system time changes. Use timerfd(3) with CLOCK_REALTIME
       and TFD_TIMER_CANCEL_ON_SET for that.

   Security
       The interactive boolean parameters can be used to control whether polkit[1] should interactively ask the
       user for authentication credentials if required.

       The polkit action for SetTimezone() is org.freedesktop.timedate1.set-timezone. For SetLocalRTC() it is
       org.freedesktop.timedate1.set-local-rtc, for SetTime() it is org.freedesktop.timedate1.set-time and for
       SetNTP() it is org.freedesktop.timedate1.set-ntp.  ListTimezones() does not require any privileges.

EXAMPLES

       Example 1. Introspect org.freedesktop.timedate1 on the bus

           $ gdbus introspect --system \
             --dest org.freedesktop.timedate1 \
             --object-path /org/freedesktop/timedate1

VERSIONING

       These D-Bus interfaces follow the usual interface versioning guidelines[2].

SEE ALSO

       More information on how the system clock and RTC interact[3]

NOTES

        1. polkit
           https://www.freedesktop.org/software/polkit/docs/latest/

        2. the usual interface versioning guidelines
           http://0pointer.de/blog/projects/versioning-dbus.html

        3. More information on how the system clock and RTC interact
           https://lists.freedesktop.org/archives/systemd-devel/2011-May/002526.html