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
           https://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