On Thursday, February 21, 2019 at 11:16:00 PM UTC-5, Jon Zeppieri wrote:
>
>
>
> On Thu, Feb 21, 2019 at 10:12 PM Brian Adkins <lojic...@gmail.com
> <javascript:>> wrote:
>
>> On Thursday, February 21, 2019 at 9:54:23 PM UTC-5, Jon Zeppieri wrote:
>>>
>>>
>>>
>>> On Thu, Feb 21, 2019 at 9:48 PM Brian Adkins <lojic...@gmail.com> wrote:
>>>
>>>> On Thursday, February 21, 2019 at 9:35:58 PM UTC-5, Brian Adkins wrote:
>>>>>
>>>>> On Thursday, February 21, 2019 at 9:26:07 PM UTC-5, Brian Adkins wrote:
>>>>>>
>>>>>> I'm using the (today) function from the gregor library. It was
>>>>>> returning tomorrow instead of today, so I thought the problem was the
>>>>>> timezone on my Ubuntu server. I configured the timezone to be US/Eastern
>>>>>> via: sudo dpkg-reconfigure tzdata
>>>>>>
>>>>>> Now the date command returns: Thu Feb 21 21:23:43 EST 2019 as
>>>>>> expected.
>>>>>>
>>>>>> Unfortunately, (system-tzid) returns: "Etc/UTC"
>>>>>>
>>>>>> So, gregor's (today) still returns tomorrow (since it's so late).
>>>>>>
>>>>>> Anyone know how to get (system-tzid) to return the correct value on
>>>>>> Ubuntu?
>>>>>>
>>>>>
>>>>> Some more info:
>>>>>
>>>>> /etc/localtime is linked as: localtime ->
>>>>> /usr/share/zoneinfo/US/Eastern
>>>>>
>>>>
>>>> I reinvoked sudo dpkg-reconfigure tzdata and chose America/New_York
>>>> instead of US/Eastern, but I still get the default "Etc/UTC" from
>>>> (system-tzid)
>>>>
>>>
>>>
>>> Huh. Could you do the following and tell me what you get?
>>>
>>> > (require tzinfo/private/generics)
>>> > (require tzinfo/private/zoneinfo)
>>> > (define zi (make-zoneinfo-source))
>>> > (zoneinfo-dir zi)
>>> "/usr/share/zoneinfo"
>>> > (detect-system-tzid zi)
>>> "America/New_York"
>>>
>>
>> > (require tzinfo/private/generics)
>> > (require tzinfo/private/zoneinfo)
>> > (define zi (make-zoneinfo-source))
>> > (zoneinfo-dir zi)
>> "/usr/share/zoneinfo"
>> > (detect-system-tzid zi)
>> #f
>>
>> Also:
>>
>> $ ls -l /etc/localtime
>> lrwxrwxrwx 1 root root 36 Feb 21 21:45 /etc/localtime ->
>> /usr/share/zoneinfo/America/New_York
>>
>> $ cat /etc/timezone
>> America/New_York
>>
>>
>
> Thanks.
>
> Okay, so first I figured that the problem was probably due to the weird
> way that I try to discover the target of an /etc/timezone symlink. (Racket
> doesn't provide that functionality, as far as I could tell at the time, and
> I guess I wanted to avoid the FFI? Even though I used it for Windows? My
> memory fails me.)
>
> But, if that method fails, it also tries getting the value from
> /etc/timezone, which you noted, is set correctly. And that method of
> getting the timezone is really simple. It just reads the file. So... hmm.
> Okay, let's do this exhaustively.
>
> 1. Verify that (system-type) is 'unix. (Just to make sure we check
> everything.)
>
> 2. In DrRacket, in the definitions window, put the following:
> ```
> #lang racket/base
>
> (require tzinfo/private/zoneinfo)
> ```
> 3. Right click on `tzinfo/private/zoneinfo` and select "Open zoneinfo.rkt."
>
> 4. In the new DrRacket window that contains the source of zoneinfo.rkt,
> click "Run."
>
> 5. Then, in the interaction pane, do:
> > (define zi (make-zoneinfo-source))
> > (tzinfo-has-tzid? zi "America/New_York")
> #t
>
> If this is #f, that would be bad, and you can stop right there.
>
> 6. Next:
> > (find-zoneinfo-directory default-zoneinfo-search-path)
> "/usr/share/zoneinfo"
>
> If you don't get the same values for this, that would be odd.
>
> 7.
> > (detect-tzid/unix (zoneinfo-dir zi)
> (find-zoneinfo-directory default-zoneinfo-search-path)
> (tzinfo->all-tzids zi))
> "America/New_York"
>
> I expect you'll either get #f here or else you'll get a string but it
> won't be a valid IANA time zone name.
>
> 8. Near the top of zoneinfo.rkt, you'll see a require line for
> "os/unix.rkt." Right click that and open the file. Run it.
>
> 9. In the interactions pane:
> > (tzid-from-env)
> #f
>
> (If this isn't #f, and it also isn't an valid IANA time zone id, that
> would be the problem.)
>
> 10.
> > (tzid-from-/etc/timezone)
> #f
>
> Based on what you wrote above, I expect you to get "America/New_York"
> here. (I get #f, but I'm on OS X.)
>
> ===
>
> I think you'll have to get unexpected results from one of these, and that
> should help us figure out the problem.
> My best guess right now is that detect-tzid/unix will return a string that
> isn't a valid IANA tzid. And that might be because you have the TZ
> environment variable set.
>
> Thank you for helping me track down this bug. If my guess is correct, I
> need to make a slight change to the code.
>
> (Summary: detect-tzid/unix tries a few different methods for determining
> the system time zone, and it stops when any one of them is non-#f. But the
> returned string is only validated against the list of IANA zones
> afterwards, so if any of those methods returns a string that isn't a valid
> time zone, it won't try any of the other methods.)
>
>
Yes, I think we found the problem:
$ ls -l /etc/localtime
lrwxrwxrwx 1 root root 36 Feb 21 21:45 /etc/localtime ->
/usr/share/zoneinfo/America/New_York
deploy@ip-172-31-10-34:~$ ls -l /usr/share/zoneinfo/America/New_York
lrwxrwxrwx 1 root root 13 Jan 1 00:05 /usr/share/zoneinfo/America/New_York
-> ../posixrules
$ racket
Welcome to Racket v7.1.
> (require racket/enter)
> (require tzinfo/private/zoneinfo)
> (enter! tzinfo/private/zoneinfo)
<pkgs>/tzinfo/tzinfo/private/zoneinfo> (define zi (make-zoneinfo-source))
<pkgs>/tzinfo/tzinfo/private/zoneinfo> (tzinfo-has-tzid? zi
"America/New_York")
#t
<pkgs>/tzinfo/tzinfo/private/zoneinfo> (find-zoneinfo-directory
default-zoneinfo-search-path)
"/usr/share/zoneinfo"
<pkgs>/tzinfo/tzinfo/private/zoneinfo> (detect-tzid/unix (zoneinfo-dir zi)
(find-zoneinfo-directory default-zoneinfo-search-path)
(tzinfo->all-tzids zi))
"posixrules"
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