Support custom timezones

[DiegoQueiroz]

When I use macros like \today, ShareLatex produces the document using server's system date.
Since the user can be in a different timezone, the document may be produced with an unexpected date.

To illustrate the problem, the current time where I live is May 17, 2015, 11:00pm (Brazil oficial time, GMT-3), but when I compile a document in ShareLatex, \today returns "May 18, 2015".

I think the API should have a timezone setting, so the datetime can be adjusted before compiling the document. The UI can also have an option to allow the user to select its timezone.

[jpallen]

In principle, we'd love to make this possible. In practice, it's very very hard. LaTeX takes it's time from the system time, with no way that I know to easily override \today with a custom timezone. There can only ever be one system time on a server, so supporting multiple timezones in an API that serves many users at once currently seems impossible. I'm open to clever workarounds though if someone can find one :)

[DiegoQueiroz]

Sorry, but setting TZ variable is not an option?

Just check out these outputs:
$ echo $TZ
America/Sao_Paulo
$ date
Mon, May 18, 2015 8:35:21 AM
$ TZ=UTC date
Mon, May 18, 2015 11:35:49 AM
$ TZ=GMT-10 date
Mon, May 18, 2015 9:36:07 PM
$ TZ=Asia/Singapore date
Mon, May 18, 2015 7:37:17 PM

So setting TZ variable before call latex binary should work as well. I just to not own a LaTeX environment ready to test it, but I think this simple change may do the trick.

[jpallen]

ok, that approach might work. I'll reopen this, thanks.

[DiegoQueiroz]

Great! :)

[DiegoQueiroz]

Just to help this implementation, there is a full documentation of TZ variable at http://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html.

Also, it would be incredible if the implementation be able to handle Daylight Saving Times (DST). I think ShareLatex UI can guess user's timezone using JavaScript and pass this info to the API.

This way, we avoid the need to keep a table to inform the DST start/end dates of each country (that would be a pain), or force the user to select its timezone/DST info.

[das7pad]

Hi!

Thank you for taking the time to write up this issue.

We are in the process of migrating to a monorepo at https://github.com/overleaf/overleaf and will mark this repository read-only soon.
You can read more about the monorepo migration at overleaf/overleaf#923.

We are going to close this issue now to avoid any confusion about the inability to comment further.

If you believe this issue still needs addressing, please create a new issue at https://github.com/overleaf/overleaf.

Thanks again!