Manual:$wgSearchForwardUrl

Search: $wgSearchForwardUrl
Set this to a URL to forward search requests to some external location.
Introduced in version:	1.4.0
Removed in version:	Still in use
Allowed values:	(URL string)
Default value:	null
Other settings: Alphabetical | By function

Details

Set this to a URL to forward search requests to some external location. If the URL includes '$1', this will be replaced with the URL-encoded search term. For example, to forward to Google you'd have something like:

$wgSearchForwardUrl = 'http://www.google.com/search?q=$1' .
                      '&domains=http://example.com' .
                      '&sitesearch=http://example.com' .
                      '&ie=utf-8&oe=utf-8';

You also need to set $wgDisableTextSearch = true; or $wgSearchForwardUrl is ignored.

From versions 1.4.8 to 1.4.15, this setting was incorrectly named $wgForwardSearchUrl in DefaultSettings.php. If you are using one of those versions then this alternative name should be used instead.