How to run Symfony dev environment under Apache by default?

Question

symfony

The built-in Symfony server runs the application in the dev environment by default , Apache in prod . How to configure Symfony so that under Apache it also starts in the dev environment by default ?
The second question is: how does Symphony know in which environment it was launched, when app.php or app_dev.php are not explicitly launched?
The third question: something confuses that when prescribing DirectoryIndex app_dev.phpthe web folder in .htaccess, the profiler strip still did not appear.

Answer 1

1. Edit .htaccess
2. There is no "implicit" launch - a completely specific file from point 1 is launched
3. DirectoryIndex is not of fundamental importance, it is more important to change RewriteRule.

Answer 2

Well, actually the third question is the answer to the first. Perhaps it was necessary to restart Apache after the change.
The second question - these files are front controllers, entry points to the application. Open them and see how they differ, it should become clear how the symphon defines the environment.
Try to read the book - One year with Symfony. It's in the first chapters about it.