Install the package:
sudo apt-get install mediawiki
Optionally install add-ons:
sudo apt-get install imagemagick mediawiki-math php5-gd
Enable MediaWiki by editing the following file and remove the '#' from the third line so that it reads 'Alias /mediawiki /var/lib/mediawiki':
sudo nano /etc/mediawiki/apache.conf
Then restart apache:
sudo /etc/init.d/apache2 restart
