- File URI scheme
The file: URL is a URL schema specified in RFC 1630 and RFC 1738, typically used to retrieve files from within one's own computer. A file: URL takes the form of file://"host"/"path"where "host" is the fully qualified domain name of the system on which the "path" is accessible, and "path" is a hierarchical directory path of the form "directory"/"directory"/.../"name". If "host" is omitted, it is taken to be "localhost".
file: URLs are rarely used in Web pages on the Internet, since they make the assumption that such a file exists on the client's computer. The "host" specifier can be used to retrieve a file from an external source, although no specific file-retrieval protocol is specified; and using it should result in a message that informs the user that no mechanism to access that machine is available.
On MS Windows systems, the normal colon (:) after a device letter has sometimes been replaced by a vertical bar (|) in file URLs. For example, to refer to file FOO.BAR in the top level directory of the C disk, the URL file:///C|/FOO.BAR was used. This reflected the original URL syntax, which made the colon a reserved character in a path part. For network shares, add an additional two slashes. For example, \hostsharedirfile.txt, becomes file:////host/share/dir/file.txt.
Mozilla browsers refuse to follow file: links on a page that it has fetched with the HTTP protocol, so that the page's own URL is an http: URL. When you click on such a link, nothing happens. The purpose is presumably security: to prevent a remote page from executing a program on the visitor's computer. The file: links work on Mozilla on pages that are local files on the user's disk. Mozilla browsers can be configured to override this security restriction as detailed in [http://kb.mozillazine.org/Firefox_:_Issues_:_Links_to_Local_Pages_Don't_Work Mozillazine's "Links to Local Pages Don't Work"] .
Mozilla browsers also treat file: URLs similarly to the Gopher protocol in the way a directory is represented textually (i.e. the source) and graphically.
Internet Explorer browsers, prior to version 7, will attempt to access file: URLs even if they reside on pages fetched over HTTP.
The original web browser,
WorldWideWeb , provided editing of resources in file: space [http://www.w3.org/People/Berners-Lee/WorldWideWeb.html] . No modern browsers replicate this ability.External links
* [http://www.cs.tut.fi/~jkorpela/fileurl.html File URLs]
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