dateadd calculations with time zone flags return incorrect results

[peter-fb]

I want all calculations to use my local time. Is this a bug or am I doing something wrong:

peter@debian:~$ date -Iseconds
2026-01-07T11:17:48+01:00

peter@debian:~$ dateutils.dadd --from-zone=localtime --zone=localtime now 24h
2026-01-08T11:17:54

peter@debian:~$ dateutils.dadd --from-zone=localtime --zone=localtime now 1d
2026-01-08T10:18:00

peter@debian:~$ dateutils.dadd --version
dateadd 0.4.11

The results of now 24h and now 1d are off by an hour, which doesn't make any sense.

[hroptatyr]

Hi Peter,
thanks for reporting this bug. A fix is in fa44ae7.

[peter-fb]

@hroptatyr Hi Sebastian,
thanks for fixing the bug so quickly. :)

I compiled the master branch and it seems to be working fine.

I also found that these two commands already print the correct time:

dateadd --zone=localtime now 24h

dateadd --zone=localtime now 1d

What's the best way to handle time zones? Which flags do I need for that? Is it best to just always use --from-zone=localtime --zone=localtime as a best practice?

[hroptatyr]

Hi again, well, "now" is special in the sense that it cannot have zone information attached. Now is now no matter where you are. That being said, I would always use --from-zone/--zone to make the intent clear.

As for 24h and 1d, they are indeed not the same on days (and in timezones) where DST switching occurs: 10 o'clock tomorrow can be different from 24 hours from 10 o'clock today.