I want to convert dates to Jalali format. The problem is I have to change some of the core files in
/modules. Is it possible to do this without jumping right into the core?
I think your best bet is Calendar_Systems module that will not do the core changes but everything else needed on the frontend.
You could set the default timezone for your site at
This will change the output of all dates on your site. You shouldn't have to edit any core files to set your sites timezone.