Wikipedia:FAQ/Technical

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Note: If you're trying to get help for a specific technical problem that isn't answered by the FAQs, try asking in Wikipedia:Troubleshooting or at the village pump.

General Technical Questions

What software is used to run Wikipedia?

We originally ran UseModWiki, a general wiki script by Clifford Adams. In January 2002, we switched to a PHP script, which in turn was completely overhauled the following July to create Wikipedia:Software Phase III.

MySQL is used for the database backend, and Apache is the web server.

The Wikipedia server's operating system is Linux.

How about the hardware?

www.wikipedia.org runs on a PC that has dual Athlon MP 1800+ processors. (Support your local non-monopoly!) It has 2GB of RAM and 36GB of storage on SCSI hard drives.

How big is the database?

The database is roughly 4 GB in size (including all languages and support tables) and growing.

Why are some of the pages scrunched together and capitalized LikeThis?

The original wiki standard is to treat anything scrunched together and capitalized LikeThis (sometimes called CamelCase) automatically as a link. This linking style was originally used by Wikipedia, but we now use free links. If you come across an old CamelCase link or article, you should rename (move) it to the new style, so that the CamelCase name redirects to the new title.

What kind of markup language does Wikipedia use?

Wikipedia uses a very simple markup based on UseModWiki. For more details, see Wikipedia:How does one edit a page.

Why not use HTML?

The short answer is: for simplicity and security.

And now the longer answer. Wikipedia, and wikis in general, are meant to be edited on the fly. HTML is not easy to use when you simply want to write an article. Creating links gives us a particularly dramatic example. To link to the HTML article using HTML, one would have to type

Using Wikipedia markup is much easier:

[[HTML]]

Then there's security. Different web browsers have bugs that can be exploited via HTML. Malicious users could also do things like JavaScript popup windows or page redirects if they had full HTML ability on Wikipedia. Several "experimental" sites that allowed full-HTML editing have suffered such attacks, including a couple other wikis that allowed arbitrary HTML.

So we can't use any HTML?

Alright, alright, a few tags work. Also, HTML table tags are the only way to create tables at the moment. See Wikipedia:How does one edit a page. However, there's been some rumbling among the software developers that most HTML tags are deprecated. There's also been discussion about wiki syntax for tables; see m:WikiShouldOfferSimplifiedUseOfTables for a very old beginning, and m:Wiki markup tables for more recent activity.

What about non-ASCII characters, and special symbols?

Just because the codes are defined in HTML4 doesn't mean they actually work in any common browser. See the Wikipedia:Special characters page for a detailed discussion of what is generally safe and what isn't. This page will be updated over time as more browsers come to support more features.

What about math topics, which require many special symbols, fonts, and graphics?

See the discussion in talk:Wikipedia_FAQ. (This is just an interim location.) See m:Math Markup.

What happens if two or more people are editing the same page?

The second person (and later persons) to save the page will receive an "edit conflict" message, and the opportunity to merge their changes into the most-currently-saved version. The wiki will also check for a conflict if you are editing and do a preview of the edit. Multiple consecutive conflicts are noticed, and will generate a slightly different message.

Is it possible to download the contents of Wikipedia?

Yes, the whole contents of Wikipedia can be downloaded. See wikipedia:database download.

Will there / should there be a CPAN module to standardize querying of Wikipedia?

Maybe. A full-blown module might be overkill, though. If you're just after retrieving a topic page, the following Perl sample code works. In this case, it retrieves and lists this page, but modifications to the '$url variable for other pages should be obvious enough. Once you've got the page source, Perl regular expressions are your friend in finding wiki links.

 #!/usr/bin/perl
 use LWP;

 $browser = LWP::UserAgent->new();
 $url =  "http://www.wikipedia.org/wiki/Wikipedia%3AFAQ";
 $webdoc = $browser->request(HTTP::Request->new(GET> $url));
 if ($webdoc->is_success) #...then it's loaded the page OK
 {
   print $webdoc->title, "\n\n"; # page title
   print $webdoc->content, "\n\n"; # page text
 }

Note that all (English) Wikipedia topic entries can be accessed using the conventional prefix "http://www.wikipedia.org/wiki/", followed by the topic name (with spaces turned into underscores, and special characters encoded using the standard URL encoding system).

How do recover a password I have forgotten?

If you entered your e-mail address when you signed up, you can have a new password generated. Click on the "Log in" link in the upper-right corner. Enter your user name, and click the button near the bottom of the page called "Mail me a new password". You should receive an e-mail message with a new random password; you can use it to log in, then go ahead and change you password to something you'll remember in your preferences.

I have a problem not on this list, where do I go?

See Wikipedia:Troubleshooting Wikipedia