PHP.ini Configuration

The php.ini file is the initialization file for PHP and is responsible for configuring many aspects of PHP’s behavior. PHP searches for and loads this configuration file from various locations.

Search Order for `php.ini`

PHP attempts to find and load the php.ini configuration file from the following locations:

SAPI module specific location
The PHPRC environment variable (as of PHP 5.2.0)
Predefined registry keys on Windows (as of PHP 5.2.0)
Current working directory (except for CLI)
The web server’s directory (for SAPI modules), or the directory of PHP (otherwise in Windows)
The directory from the --with-config-file-path compile-time option, or the Windows directory (C:\windows or C:\winnt)

For more information, see the PHP documentation: PHP Configuration File.

Syntax of `php.ini`

The syntax in the php.ini file is simple:

Whitespace and lines beginning with a semicolon (;) are ignored.
Section headers (e.g., [Foo]) are also ignored, even though they may be used in future versions of PHP.
Directives following the section heading [PATH=/www/mysite] apply only to PHP files in the /www/mysite directory.
Similarly, directives following the section heading [HOST=www.example.com] apply only to PHP files served from www.example.com.

Currently, [PATH=] and [HOST=] sections only work under CGI/FastCGI environments. For more details, visit: INI Sections.

Directive Syntax

Directives in php.ini are specified using the following syntax:

directive = value

Directive names are case-sensitive (e.g., foo=bar is different from FOO=bar).
The value can be:
- A string, a number, a PHP constant (e.g., E_ALL or M_PI),
- One of the INI constants (On, Off, True, False, Yes, No, None),
- An expression (e.g., E_ALL & ~E_NOTICE), or
- A quoted string (e.g., "bar"), or
- A reference to a previously set variable or directive (e.g., ${foo}).

Boolean Flags

On and Off values are used to set boolean flags.
Flags can be turned on using the values 1, On, True, or Yes.
Flags can be turned off using the values 0, Off, False, or No.
An empty string can be denoted by:
- Not writing anything after the equal sign (e.g., foo =),
- Using the None keyword (e.g., foo = None), or
- Using the string 'None' (e.g., foo = "None").

About `php.ini` Files

PHP comes packaged with two php.ini files:

php.ini-production: Contains settings optimized for security, performance, and best practices for production environments. However, these settings may break compatibility with older or less secure applications. It’s recommended to use php.ini-production in production and testing environments.
php.ini-development: Similar to php.ini-production, but with more verbose error reporting. This version should be used only in development environments to avoid leaking sensitive information to users.

Quick Reference for Production vs Development

Below are key differences between php.ini-production and php.ini-development regarding PHP’s default behavior. These settings are designed to help optimize PHP for either production or development environments.

Setting	Default Value	Development Value	Production Value
display_errors	On	On	Off
display_startup_errors	Off	On	Off
error_reporting	E_ALL & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED	E_ALL	E_ALL & ~E_DEPRECATED & ~E_STRICT
html_errors	On	On	On
log_errors	Off	On	On
max_input_time	-1 (Unlimited)	60	60
output_buffering	Off	4096	4096
register_argc_argv	On	Off	Off
request_order	None	”GP"	"GP”
session.gc_divisor	100	1000	1000
session.hash_bits_per_character	4	5	5
short_open_tag	On	Off	Off
track_errors	Off	On	Off
url_rewriter.tags	”a=href, area=href, frame=src, form="	"a=href, area=href, frame=src, input=src, form=fakeentry"	"a=href, area=href, frame=src, input=src, form=fakeentry”
variables_order	”EGPCS"	"GPCS"	"GPCS”

php.ini Options

user_ini.filename: Name for user-defined php.ini files. Default is .user.ini.
user_ini.cache_ttl: Time-to-live for user-defined php.ini files, in seconds. Default is 300 seconds (5 minutes).

Language Options

engine: Enables the PHP scripting language engine under Apache.
short_open_tag: Determines if PHP will recognize <? and ?> as PHP tags. Recommended to use <?php and ?>.
precision: Number of significant digits displayed in floating point numbers.
output_buffering: Controls how much output data PHP should keep before sending it to the client.
implicit_flush: Enables implicit flushing after every output block.

Additional Security Features

disable_functions: Disables certain PHP functions for security reasons.
disable_classes: Disables certain classes for security reasons.
open_basedir: Limits file operations to a defined directory and below.
zend.enable_gc: Enables or disables the circular reference collector.

For more detailed settings and configurations, refer to the PHP Documentation.

PHP.ini Configuration