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How to change configuration settings

Running PHP as Apache module

When using PHP as an Apache module, you can also change the configuration settings using directives in Apache configuration files (e.g. httpd.conf) and .htaccess files (You will need "AllowOverride Options" or "AllowOverride All" privileges)

With PHP 3.0, there are Apache directives that correspond to each configuration setting in the php3.ini name, except the name is prefixed by "php3_".

With PHP 4.0, there are several Apache directives that allow you to change the PHP configuration from within the Apache configuration file itself.

php_value name value

This sets the value of the specified variable.

php_flag name on|off

This is used to set a Boolean configuration option.

php_admin_value name value

This sets the value of the specified variable. "Admin" configuration settings can only be set from within the main Apache configuration files, and not from .htaccess files.

php_admin_flag name on|off

This is used to set a Boolean configuration option.

Example 4-2. Apache configuration example

<IfModule mod_php4.c>
  php_value include_path ".:/usr/local/lib/php"
  php_admin_flag safe_mode on
</IfModule>
<IfModule mod_php3.c>
  php3_include_path ".:/usr/local/lib/php"
  php3_safe_mode on
</IfModule>

Note: PHP constants do not exist outside of PHP. For example, in httpd.conf do not use PHP constants such as E_ALL or E_NOTICE to set the error_reporting directive as they will have no meaning and will evaluate to 0. Use the associated bitmask values instead. These constants can be used in php.ini

Other interfaces to PHP

Regardless of the interface to PHP you can change certain values at runtime of your scripts through ini_set(). The following table provides an overview at which level a directive can be set/changed.

Table 4-1. Definition of PHP_INI_* constants

ConstantValueMeaning
PHP_INI_USER1Entry can be set in user scripts
PHP_INI_PERDIR2 Entry can be set in .htaccess and VHost directives in httpd.conf.
PHP_INI_SYSTEM4 Entry can be set in php.ini or httpd.conf (but not in VHost blocks in httpd.conf).
PHP_INI_ALL7Entry can be set anywhere

You can view the settings of the configuration values in the output of phpinfo(). You can also access the values of individual configuration settings using ini_get() or get_cfg_var().

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