Installing MediaWiki Guide

MediaWiki, the Wiki engine powering this site, is fully open-source and free. It seems to be robust, and reasonably fast. Configuring and installing it, however, is not so easy. This guide is a tutorial for MediaWiki administrators.

Prerequisites

• Apache
• PHP
• MySQL with InnoDB support! The tables created by MediaWiki will use the InnoDB engine. I don't think it is possible to use MyISAM tables.

Optional Software

• APC. This is a PHP accelerator.
• memcached. This a daemon caching SQL requests in memory. If you run two Wikis on the same machine, beware that it can cause serious problems. If there is a single memcached daemon running, and both Wikis use it, they will interfere and one Wiki will end up serving the contents of the other. A solution can be to run memcached on several machines, or maybe on the same machine but with different ports. However, this last option on Mac OS X seems to be tricky.
• ImageMagick, in order to generate the images thumbnail. This can also be done via PHP if GD support is included; however ImageMagick is recommended since it produces better quality thumbnails.

Installation

• Installation is easy, just download MediaWiki from Sourceforge and uncompress the tarball in a directory that Apache can serve. Then follow the instructions on the README to perform the initial configuration. It involves running a PHP script that will configure the Wiki for you.

• Warning: the initial administrator account is named "WikiSysop", and is case sensitive. If you forget it, search it on the MySQL database directly.

• It is also recommended to increase your PHP memory_limit variable in php.ini. Else sometimes MediaWiki will fail with a message such as:

Fatal error: Allowed memory size of 8388608 bytes exhausted (tried to allocate 80629 bytes) in /var/www/wikistuff/includes/Parser.php on line 206

I set this variable to 30 MB.

Configuration

• Using memcached

• Obtaining nice URLs: A guide to remove "index.php" from the URL is available online. However I don't find it very clear. The important steps are:
  • Unpack the MediaWiki in a directory NOT named "wiki", for example "wikistuff" will do.
  • In LocalSettings.php, set $wgScriptPath = "/wikistuff"; and $wgArticlePath = "/wiki/$1";
  • Write an Alias rule for Apache: add the line

Alias /wiki /filesystem/path/to/wikistuff/index.php

in the Apache configuration file. Note: don't add the second line as mentionned in the guide!

• Disabling automatic account creation and anonymous edits. Add the following lines to LocalSettings.php:

$wgGroupPermissions['*']['edit'] = false;
$wgGroupPermissions['*']['createaccount'] = false;

• Disabling anonymous reading. Add the following lines to LocalSettings.php:

# Pages anonymous (not-logged-in) users may see
$wgWhitelistRead = array( "Main Page", "Special:Userlogin", "-", "MediaWiki:Monobook.css" );

$wgGroupPermissions['*']['read'] = false;

• Customizing logo (note that it should start with the name of the wiki directory, eg /wiki here):

$wgLogo = "/wiki/path/to/logo.png";

• Allowing images uploads (set $wgUseImageMagick to false if you want to use GD instead of ImageMagick to create the thumbnails):

$wgEnableUploads = true;
$wgUseImageResize = true;
$wgUseImageMagick = true;
$wgImageMagickConvertCommand = "/usr/bin/convert";

Administration

• Deleting/removing an user is not possible with MediaWiki. You can, however, change the password with the following SQL request:

UPDATE user SET user_password = MD5(CONCAT(user_id, '-', 
  MD5('somepass'))) WHERE user_name = 'someuser';

Usage

• Editing Guide, very helpful