[Tutor] Scheduling Python Execution

[Steven D'Aprano]

On 15/04/13 19:23, Zaki Akhmad wrote:
> On Mon, Apr 15, 2013 at 3:51 PM, Alan Gauld <alan.gauld at btinternet.com> wrote:
>
>> multiple cron jobs will be less work for your computer than running a long
>> term program constantly checking times and launching your scripts... That's
>> called reinventing the wheel with a square one...
>>
>> There are more modern (and more efficent) replacements for cron but given
>> your requirements cron still looks like the best bet.
>
> Actually,
>
> I want to write a twitter bot which runs on a specific time.

That is exactly what cron is designed to do. Although given that the time you want will vary, my guess is that the lesser-known "at" job will be better.

Another option is the sched module, that lets you schedule tasks to run while your program is idling. It is not a replacement for cron or at, since it requires your program to be running. But for simple needs, it may do the job.

http://docs.python.org/2/library/sched.html
http://pymotw.com/2/sched/



>For an
> idea, I'd like to have this twitter bot tweet every sunrise and
> sunset, everyday. Since everyday the sunrise and the sunset time are
> vary, what are the best way to do it?

Sunrise and sunset *where*?

Because the world is a globe, sunrise and sunset vary from place to place. Even in one place, they also vary at different times of the year. If you google for "sunrise sunset algorithm", you may find a formula for calculating the time of each at a given latitude and longitude. Or not. I don't really know how complicated it is.


> Should I entered the sunset and the sunrise manually?

I don't know about "manually", but there's no standard Python command for giving you sunset and sunrise. You'll either need to find an existing program that does it, or write one yourself.




-- 
Steven