Help:URL

URLs in external links

A link in external link style can be of the forms:

target: http://meta.wikimedia.org/ is rendered as http://meta.wikimedia.org/
[ target label ], with a blank space in between: [http://meta.wikimedia.org/ wikimedia] gives wikimedia (see also Help:Piped link)
[ target ] - these are automatically labelled with serial numbers 1, 2, 3, ...: [http://meta.wikimedia.org/] gives [1]

The target is a URL which can start with "http://" or "ftp://";

"file://" does not work by default. If enabled it only works in MSIE. To enable it, add a $wgUrlProtocols entry to LocalSettings.php; see the $wgUrlProtocols in DefaultSettings.php for example.

All characters of the URL must be among:

A-Z a-z 0-9 ._\/~%-+&#?!=()@

If a URL contains a different character it should be converted; for example, ^ has to be written %5e, the hexadecimal ASCII value with a percent sign in front. A blank space can also be converted into an underscore.

Conversion:

      "   #   $   %   &   '   *   ,   :   ; 
%20 %22 %23 %24 %25 %26 %27 %2a %2c %3a %3b

 <   >   ?   [   ]   ^   `   {   |   }
%3c %3e %3f %5b %5d %5e %60 %7b %7c %7d

For the other characters either the code or the character can be used in internal and external links, they are equivalent. The system does a conversion when needed. E.g.

[[%C3%80_propos_de_M%C3%A9ta]]

is rendered as À_propos_de_Méta, almost like À propos de Méta, which leads to this page on Meta with in the address bar the URL

http://meta.wikipedia.org/wiki/%C3%80_propos_de_M%C3%A9ta

while http://meta.wikipedia.org/wiki/À_propos_de_Méta leads to the same.

See also (in Wikipedia): Internationalized domain names and Punycode.

Percent-encoding

For ASCII characters (up to decimal 127, hex. 7F) percent-encoding simply means adding % to the hex. value, e.g. for a tilde ~ (decimal 126, hex. 7E) it's %7E. Otherwise (non-ASCII) convert it first to UTF-8 and then percent-encode it. Example:

Convert the character to Unicode, e.g. Latin-1 192 (hex. C0) to À (u+00C0), or windows-1252 131 (hex. 8B) to Š (u+0160).
Convert Unicode to bits, 00000000 11000000 (u+00C0), or 00000001 01100000 (u+0160).
Build groups of six bits from the right adding leading zeros if necessary until the rest are zeros: 000011 000000 (u+00C0), or 000101 100000 (u+0160).
Add 10 in front of all but the leftmost group. 2 bits + 6 bits = 8bits, also known as octet.
If there are only two groups, and the first (left) starts with 0:
1. Add 11 to the left: 11 000011 10 0000000 (u+00C0), or 11 000101 10 100000 (u+0160).
2. Convert the octets to hex., add percent in front, ready: %C3%80 (u+00C0), or %C5%A0 (u+0160).
If the first (left) of two groups starts with 1:
Add 111 00000 10 to the left, then percent-encode three octects, %E0%??%??
If there are three groups, the first (left) starting with 00 (000001 up to 001111):
Replace 00 by 111 0, percent-encode three octects, ready, result %E?%??%??.
Otherwise it's at least 010000 000000 000000 (u+10000) needing four UTF-8 octets:
1111 0000 10 010000 10 000000 10 000000 would be %F0%90%80%80.

URLs of pages within the projects

See w:Wikipedia:URLs. On other projects everything works the same, except that the domain names vary:

xx.wikipedia.org with xx the language code, see m:Complete list of language Wikipedias available
meta.wikimedia.org (meta.wikipedia.org redirects there)
xx.wiktionary.org
xx.wikiquote.org
xx.wikibooks.org
xx.wikisource.org
sep11.wikipedia.org

A URL starting with www.wikipedia.org redirects to the corresponding one starting with en; only www.wikipedia.org itself leads to a portal page instead of the main page of the English Wikipedia: http://www.wikipedia.org

In projects outside Wikimedia the "w/" in URLs like http://www.wikipedia.org/w/wiki.phtml?title=Main_Page&action=history is sometimes not used, sometimes different, e.g.:

The default is /wiki/wiki.phtml, with in DefaultSetting.php [2]:

$wgScriptPath = "/wiki";
$wgScript     = "{$wgScriptPath}/wiki.phtml";

There may be other variations, compare:

Use in templates

For use in templates, note that all URLs on e.g. the English Wikipedia can be written in the form

http://en.wikipedia.org/w/index.php?title={{{1}}}

This requires {{{1}}} to be written with underscores and escape codes (if applicable). To benefit from the conversion carried out by fullurl, two parameters are needed:

{{fullurl:{{{1}}}|{{{2}}}}}

(see Template talk:Url 2p). An example with the second parameter in fullurl fixed is w:template:ed ( talk edit history links ) containing the link [{{fullurl:Template:{{{1}}}|action=edit}} {{MediaWiki:Edit}} {{{2|{{{1}}}}}}].

This works for a link in external link style to a page in the same project. We can use localurl for a link to a project which uses the same string in the URL between the server name and the question mark ($wgScript, on Wikimedia "/w/index.php"), but not for links to other projects.

Old versions of pages

All old versions of all pages are numbered (with oldid) approximately in the order of becoming an old version, i.e. in chronological order of the next edit of the same page.

http://meta.wikimedia.org/w/wiki.phtml?title=Help:Link&oldid=53587 - normal link to old page
http://meta.wikimedia.org/w/wiki.phtml?oldid=53587 - no page name in the URL, goes to the correct page
http://meta.wikimedia.org/w/wiki.phtml?title=Help:Link&oldid=53588 - number and name do not correspond; the name is ignored
http://meta.wikimedia.org/w/wiki.phtml?title=abc&oldid=53587 - non-existing page name; oldid is ignored, works like going to a non-existing page, except for the links to assumed previous and next versions, and on editing, for the warning of editing an old version of a page.

New pages

New pages are numbered (with curid) chronologically.

http://meta.wikimedia.org/w/wiki.phtml?title=x&curid=9906 - gives the page with correct full name

Edit

Examples:

Edit the whole page: http://meta.wikimedia.org/w/wiki.phtml?title=Help:URL&action=edit
Edit the 5th section: http://meta.wikimedia.org/w/wiki.phtml?title=Help:URL&action=edit&section=5
Add at the end: http://meta.wikimedia.org/w/wiki.phtml?title=Help:URL&action=edit&section=1000 (use large section number)
Ditto with "Post a comment" feature: http://meta.wikimedia.org/w/wiki.phtml?title=Help:URL&action=edit&section=new

Purge

In some cases of caching problems, to update a page it can help to use "action=purge", in a URL like http://www.lensovet.net/~sysadmin/w/index.php?title=Help:URL&action=purge

Kinds of dead links

There can be various kinds of errors in the URL. With some the server is not even reached, with others the server takes some action. The server may also go to the correct page and just ignore a wrong parameter or anchor.

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