What order does PHP read configuration from?

PHP configuration can be made in a number of different places:

• php.ini
• httpd.conf
• .htaccess
• within a php script via ini_set()
• any more?

Some configuration settings can only be set in certain places an开发者_如何学编程d there's certain Apache and PHP settings that would prevent you from doing any PHP config changes in .htaccess or with your PHP script. But assuming that a given PHP setting can be set in all of the above places, in what order is this configuration read? In other words what overrides what? (I'm assuming that ini_set() overrides any of the previous settings).

There's compile-time settings before php.ini. The rest of the stages aren't really "configuration". They're more of a way to override settings established in a previous stage. PHP will quite happily run without any other config directives in php.ini/http.conf/.htaccess. php.ini does list (almost?) all the configuration settings available, but that's just a courtesy so you don't have to dig around in the docs to find the one setting you do want to override.

You named them in the correct order.

I don't recommend setting configuration in any other place than a php.ini though.

There are also per-directory php.ini configurations and I don't know which comes first, .htaccess or the directory php.ini but I would guess the .htaccess first and php.ini after.

Apache loads PHP, so Apache's config is read first. .htaccess is also handled by the webserver, so I'm guessing that will be second. Thirdly PHP is loaded. It checks for PHP.ini's in several locations. Also see here. Finally the ini_set is checked runtime.

First, You can use a user.ini file. I think PHP will read it from the bigger to the smaller, I mean from httpd.conf -> php.ini (and then user.ini if set) -> .htacess -> ini_set()