PHP : Web Basics - [8.23] Reading Configuration Variables

8.23.1 Problem

You want to get the value of a PHP configuration setting.

8.23.2 Solution

Use ini_get( ):

// find out the include path:
$include_path = ini_get('include_path');

8.23.3 Discussion

To get all configuration variable values in one step, call ini_get_all( ). It returns the variables in an associative array, and each array element is itself an associative array. The second array has three elements: a global value for the setting, a local value, and an access code:

// put all configuration variables in an associative array
$vars = ini_get_all( );
print_r($vars['include_path']);
Array
(
    [global_value] => .:/usr/local/lib/php/
    [local_value] => .:/usr/local/lib/php/
    [access] => 7
)

The global_value is the value set from the php.ini file; the local_value is adjusted to account for any changes made in the web server's configuration file, any relevant .htaccess files, and the current script. The value of access is a numeric constant representing the places where this value can be altered. Table 8-3 explains the values for access. Note that the name access is a little misleading in this respect, as the setting's value can always be checked, but not adjusted.

Table 8-3. Access values

Value	PHP constant	Meaning
1	PHP_INI_USER	Any script, using ini_set( )
2	PHP_INI_PERDIR	Directory level, using .htaccess
4	PHP_INI_SYSTEM	System level, using php.ini or httpd.conf
7	PHP_INI_ALL	Everywhere: scripts, directories, and the system

A value of 6 means the setting can be changed in both the directory and system level, as 2 + 4 = 6. In practice, there are no variables modifiable only in PHP_INI_USER or PHP_INI_PERDIR, and all variables are modifiable in PHP_INI_SYSTEM, so everything has a value of 4, 6, or 7.

You can also get variables belonging to a specific extension by passing the extension name to ini_get_all( ):

// return just the session module specific variables
$session = ini_get_all('session');

By convention, the variables for an extension are prefixed with the extension name and a period. So, all the session variables begin with session. and all the Java variables begin with java., for example.

Since ini_get( ) returns the current value for a configuration directive, if you want to check the original value from the php.ini file, use get_cfg_var( ):

$original = get_cfg_var('sendmail_from'); // have we changed our address?

The value returned by get_cfg_var( ) is the same as what appears in the global_value element of the array returned by ini_get_all( ).