systemd and timezone (was: Re: difference in seconds between two formatted dates ...)
I am not going to discuss code posted by Albretch, despite it has
serious issues from my point of view. This is a response to Greg.
On 20/12/2023 22:04, Greg Wooledge wrote:
The selection of the computer's default time zone by its owner is not
in ANY way related to the computer's geographic location.
The default time zone has nothing to do with systemd, nor with any other
init system that may be in place. Systemd does not know or care about
the system's default time zone.
See systemd-timedated.service(8) and org.freedesktop.timedate1(5)
busctl introspect org.freedesktop.timedate1 /org/freedesktop/timedate1
# Values are stripped
org.freedesktop.DBus.Properties interface -
.PropertiesChanged signal sa{sv}as
org.freedesktop.timedate1 interface -
.ListTimezones method -
.SetLocalRTC method bbb
.SetNTP method bb
.SetTime method xbb
.SetTimezone method sb
.CanNTP property b
.LocalRTC property b
.NTP property b
.NTPSynchronized property b
.RTCTimeUSec property t
.TimeUSec property t
.Timezone property s
Desktop environments use this interface.
Again, you're not making any sense. How does this computer know where
it is geographically located? Does it have GPS hardware inside it?
And even knowing a user's geographic location is *not* enough to know
which time zone the user wishes to use. Time zones are poliitical.
I would not be surprised to find an "Automatic time zone" checkbox in
GUI settings similar to e.g. Android. I am unsure however if it has been
implemented by any Debian package. Ubuntu installer is able to guess
time zone. Likely it is based on a GeoIP database and an external server
to determine outgoing IP address.
List of WiFi networks around is enough to get location without GPS.
$LANG may improve this guess to resolve political (ethnic) ambiguity.
My impression is that there are enough users who do not know their
timezone and enough users would be happy to get correct timezone
automatically. Some of them choose a timezone having slight differences
and later complain that the TZ DB is not precise.
To configure default timezone system-wide I still recommend
dpkg-reconfigure tzdata
since it handles the case of obsolete application. I would not neglect
systemd though since it is widespread now. So output of the following
commands maybe useful to diagnose issues related to localtime
timedatectl
set | grep -E '^(TZ|LANG|LC_.*)='
Reply to: