There are several Apache directives that allow you to change the PHP configuration from within the Apache configuration files. For a listing of which directives are PHP_INI_ALL, PHP_INI_PERDIR, or PHP_INI_SYSTEM.
Sets the value of the specified directive. Can be used only with PHP_INI_ALL and PHP_INI_PERDIR type directives. To clear a previously set value use none as the value.
A handy trick to pick up parse errors in test_file.php if you can't set display_errors in php.ini or use .htaccess:
ini_set ('display_errors', true);
Where a configuration setting may be set
These modes determine when and where a PHP directive may or may not be set, and each directive within the manual refers to one of these modes. For example, some settings may be set within a PHP script using ini_set(), whereas others may require php.ini or httpd.conf.
For example, the output_buffering setting is PHP_INI_PERDIR therefore it may not be set using ini_set(). However, the display_errors directive is PHP_INI_ALL therefore it may be set anywhere, including with ini_set().
|PHP_INI_USER||Entry can be set in user scripts (like with ini_set()) or in the Windows registry. Since PHP 5.3, entry can be set in .user.ini|
|PHP_INI_PERDIR||Entry can be set in php.ini, .htaccess, httpd.conf or .user.ini (since PHP 5.3)|
|PHP_INI_SYSTEM||Entry can be set in php.ini or httpd.conf|
|PHP_INI_ALL||Entry can be set anywhere|