PHP configuration

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PHP is a web template system that accidentally grew up into a fairly general language. PHP's syntax, capabilities, and execution model bear vague similarities to Perl; scripts are loaded by an "interpreter", compiled to bytecode, and then executed. The PHP interpreter can be run from the command line, CGI-style, or more commonly as an in-process Apache module.

MediaWiki compatibility

For the allowed set of PHP versions you can use with your version of MediaWiki, see Compatibility#PHP.

Installation

Please see https://php.net/install.

Compile-time options

Required

The following extensions are required by MediaWiki:

Perl Compatible Regular Expressions
Session
Standard PHP Library
Document Object Module
iconv character set conversion library
JSON (alternatively, the pecl-json-c fork)
mbstring multibyte character string support
fileinfo MIME type detection
intl Unicode normalization
calendar Support for conversion between different calendars
At least one database driver:

MySQL and PostgreSQL through PDO are not supported

Perl Compatible Regular Expressions, Session, Standard PHP Library, and JSON are enabled by default; Perl Compatible Regular Expressions and Standard PHP Library cannot be disabled since PHP 5.3.

Optional

MediaWiki either needs or wants a number of optional features of PHP that need to be enabled at compile time:

zlib compression library, optionally to compress the file cache
sockets support for network communication, if using memcached
exif functions to display EXIF data from uploaded images ($wgShowEXIF ).

Example

We are successfully working with these compiler options:

'./configure' \
  '--with-mysqli=mysqlnd' \
  '--with-pdo-mysql=mysqlnd' \
  '--with-apxs2=/usr/sbin/apxs2' \
  '--with-zlib' \
  '--with-ldap' \
  '--with-gd' \
  '--with-jpeg-dir' \
  '--with-iconv-dir' \
  '--enable-mbstring'

In detail, these configure options do the following:

--with-mysqli=mysqlnd: Include MySQLi (MySQL improved) support. The MySQL native driver will be used when value is mysqlnd.
--with-pdo-mysql=mysqlnd: PDO: MySQL support. The native driver will be used when value is mysqlnd.
--with-apxs2=/usr/sbin/apxs2: this is required if you want to build mod_php. APXS is for configuring compilation of an Apache module. You will need to change (or omit the path) for your specific system.
--with-zlib: Allows PHP to read / write zipped files and send compressed data to Apache ... or something like that
--with-ldap: Important if you want your wiki users to be verified by LDAP
--with-gd: Use this if you want image processing 'within' PHP, else you can use ImageMagick. Because this option requires that you have various libraries installed... but presumably IM has the same deps... oh well...
--with-jpeg-dir: Seems nonsensical
--with-iconv-dir: Seems nonsensical
--enable-mbstring: Allows multibyte character string support. This is optional, as slower custom code will be used if not available.

Opcode caching

See Manual:Performance tuning

Due to MediaWiki's large codebase, it is highly recommended that a system be used to cache the compiled scripts; the opcache PHP extension can be used for this. PHP usually comes with this extension pre-installed and enabled.

Runtime configuration (php.ini)

Some settings in php.ini affects MediaWiki behavior and some of them are incompatible with MediaWiki.

magic_quotes_gpc: This options adds quotes to data in $_GET, $_POST and $_COOKIES. MediaWiki can work with this option turned on, but will have to remove these quotes and thus will be slower.
magic_quotes_runtime: This option corrupts data input unpredictably by adding quotes in e.g. opened files, data received from database etc. MediaWiki will refuse to install if this option is turned on.
magic_quotes_sybase: same as magic_quotes_runtime
mbstring.func_overload: This option causes errors and may corrupt data unpredictably; MediaWiki will refuse to install if this option is turned on.
zend.ze1_compatibility_mode: This option causes horrible bugs; MediaWiki will refuse to install if this option is turned on.
memory_limit: MediaWiki needs sufficiently memory to work. The minimal limit should be something like 20 MB, but if you want MediaWiki to work correctly, consider using at least 50 MB.
disable_functions: To be able to find GNU diff3 and git during installation process this entry must not contain passthru
post_max_size: If you are getting the error "Some parts of the edit form did not reach the server; double-check that your edits are intact and try again." then it could be because this is set with a "MB" prefix, instead of just "M" (the former is interpreted at bytes, not megabytes).

Image Resizing

ImageMagick or the GD PHP module can be used for image thumbnailing. See Manual:Image administration#Image thumbnailing