Wikipedia:Technical FAQ
From Wikipedia, the free encyclopedia.
Overview FAQ -- Readers' FAQ -- Contributing FAQ -- Editing FAQ -- Administration FAQ -- Technical FAQ -- Problems FAQ -- Miscellaneous FAQ -- Help page
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.
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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. This is similar to Concurrent Versions System (CVS), a widely-used software version management system.
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How do I 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.
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How do I report a bug?
- The developers use the tracker on the Sourceforge site to keep track of bugs. For more information, see Bug reports.
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How do I suggest a new feature?
- Again, feature requests can be made at Sourceforge by clicking on SourceForge (http://sourceforge.net/tracker/index.php?group_id=34373&atid=411195).
- For information on using SourceForge, please see Bug reports.
- If you don't report your feature request at SourceForge, then it will probably never become implemented!!!
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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 what we now call MediaWiki.
- The Wikipedia servers' operating system is Linux.
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How about the hardware?
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Current situation
- See m:Wikimedia servers.
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History of Wikipedia Hardware
- A brief history of Wikipedia serving:
- Phase I: January 2001 - January 2002
- One of bomis' servers hosted all Wikipedia wikis running on UseModWiki software
- Phase II: January 2002-July 2002
- One of bomis' servers hosted all Wikipedia wikis; English and meta running on the php/mysql-based new software, all other languages on UseModWiki. Runs both the database and the web server on one machine.
- Phase IIIa: July 2002-May 2003
- Wikipedia gets own server, running English Wikipedia and after a bit meta, with rewritten PHP software. Runs both the database and the web server on one machine.
- One of bomis' servers continues to host some of the other languages on UseModWiki, but most of the active ones are gradually moved over to the other server during this period.
- Phase IIIb: May 2003-Feb 2004
- Wikipedia's server is given the code name "pliny". It serves the database for all phase 3 wikis and the web for all but English.
- New server, code name "larousse", serves the web pages for the English Wikipedia only. Plans to move all languages' web serving to this machine are put on hold until load is brought down with more efficient software or larousse is upgraded to be faster.
- One of bomis' servers continued to host some of the other languages on UseModWiki until it died. All are now hosted on pliny; a few more of the active ones have been gradually moved over to the new software, and an eventual complete conversion is planned.
- Phase IIIc: Feb 2004-present
- Wikipedia gets a whole new set of servers, paid for through donations to the non-profit Wikimedia Foundation.
- The new architecture has a new database server (suda), with a set of separate systems running Apache, as well as "squids" that cache results (to reduce the load). More details are at Wikimedia servers (http://meta.wikipedia.org/wiki/Wikimedia_servers).
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How about the connection?
- Network bandwidth is not a significant bottleneck.
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How big is the database?
- About 57GB on 11 April 2004 and growing at between 1 and 1.4 GB per week. This includes all languages and support tables but not images and multimedia. You can download compressed database dumps at http://download.wikipedia.org/ .
- In August 2003 the database was roughly 16 GB and uploaded images and media files took another gigabyte or so. In February 2003 it was about 4GB.
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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.
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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.
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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
-
- <a href="http://www.wikipedia.org/wiki/HTML">HTML</a>
- 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.
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So we can't use any HTML?
- Alright, alright, a few tags work. Also, HTML table tags were for a while the only way to create tables. 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 and m:MediaWiki User's Guide: Using tables for more recent activity.
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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.
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What about math topics, which require many special symbols, fonts, and graphics?
- Just use TeX! See Wikipedia:TeX markup.
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Is it possible to download the contents of Wikipedia?
- Yes, the complete text and editing history of all Wikipedia pages can be downloaded. See Wikipedia:database download.
- Note that downloading the database dumps is much preferred over trying to spider the entire site. Spidering the site will take you much longer, and puts a lot of load on the server (especially if you ignore our robots.txt (http://www.wikipedia.org/robots.txt) and spider over billions of combinations of diffs and whatnot). Heavy spidering can lead to your spider, or your IP, being barred with prejudice from access to the site. Legitimate spiders (for instance search engine indexers) are encouraged to wait about a minute between requests, follow the robots.txt, and if possible only work during less loaded hours (2:00-14:00 UTC is the lighter half of the day).
- The uploaded images and other media files are not currently bundled in an easily downloadable form; if you need one, please contact the developers on the wikitech-l mailing list (http://mail.wikipedia.org/mailman/listinfo/wikitech-l). Please do not spider the whole site to get images.
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Is there a CPAN module to query Wikipedia?
- Ed Summers has written WWW::Wikipedia (http://search.cpan.org/~esummers/WWW-Wikipedia/lib/WWW/Wikipedia.pm).
- If you're just after retrieving a topic page, the following Perl sample code works. In this case, it retrieves and lists the Main 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%3AMain_Page";
$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).
- See also m:Machine-friendly wiki interface
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Does wikipedia use cookies?
- Cookies are not required to read or edit Wikipedia, but they are required in order to log in and link your edits to a user account.
- When you log in, the wiki will set a temporary session cookie which identifies your login session; this will be expired when your browser exits (or after an inactivity timeout), and is not saved on your hard drive.
- Another cookie will be saved which lists the user name you last logged in under, to make subsequent logins just a teensy bit easier. (Actually two: one with your name, and one with your account's internal ID number; they must match up.) These cookies expire after 30 days. If this worries you, clear your cookies after completing your session.
- If you check the "remember my password" box on the login form, another cookie will be saved with a hash of your password (not the password itself). As long as this remains valid, you can bypass the login step on subsequent visits to the wiki. The cookie expires after 30 days, or is removed if you log out. If this worries you, don't use the option. (You should probably not use it on a public terminal!)
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Is my password secure?
- When you log in, passwords are sent in plain text across the Internet. So a passive observer — say, someone on your local area network or at your ISP — would be able to read your password as you log in.
- Wikipedia stores passwords as a salted MD5 hash. This means that if we have a security breach and someone reads our hard drive, it will generally be difficult for them to get your password, requiring weeks or months of computation time per password. The exception is if you use a password which is a word in any language, a person's name, a phonetic spelling of a word, etc. Then they may be able to break our encryption in minutes.
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The software that runs Wikipedia is great! Can I use it for my site?
- See first Wiki software for a list of wiki scripts. MediaWiki, the software that runs Wikipedia, is available from m:MediaWiki.
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I have a problem not on this list, where do I go?
- See Troubleshooting - if it's not on there try the village pump
Overview FAQ -- Readers' FAQ -- Contributing FAQ -- Editing FAQ -- Administration FAQ -- Technical FAQ -- Problems FAQ -- Miscellaneous FAQ -- Help page http://www.waterheatersmall.com/default.asp
