bug#63349: Bug in date when using UTC/GMT timeszones in the TZ variable

[Andreas Schwab]

On Mai 07 2023, Eiríkur Hjartarson via GNU coreutils Bug Reports wrote:

> Now the "bug":

It's not a bug.

> $ TZ=Europe/Riga date --iso-8601=minutes -d "2024-01-01T00:00-05:00"
> 2024-01-01T07:00+02:00
>
> $ TZ=UTC+2 date --iso-8601=minutes -d "2024-01-01T00:00-05:00"
> 2023-01-01T03:00-02:00
>
> That is: the first command gives me the time and date in Riga when it's
> midnight at new year's eve in New York.
>
> The second command should do the same but instead gives the time in
> Godthab Greenland.

That's not how TZ works.

https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html
says about the offset:

    Indicates the value added to the local time to arrive at Coordinated
    Universal Time. ...  If preceded by a '-', the timezone shall be
    east of the Prime Meridian; otherwise, it shall be west (which may
    be indicated by an optional preceding '+' ).

Thus TZ=UTC+2 means two hours before UTC.

-- 
Andreas Schwab, schwab@linux-m68k.org
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