WordPress at a glance
filter is not described

get_search_query filter-hook . WP 2.3.0

Filters the contents of the search query variable.

Usage

add_filter( 'get_search_query', 'filter_function_name_403' );
function filter_function_name_403( $search ){
	// filter...

	return $search;
}
$search(mixed)
Contents of the search query variable.

Where the hook is called

get_search_query()
wp-includes/general-template.php 3576
$query = apply_filters( 'get_search_query', get_query_var( 's' ) );

Where the hook is used (in WP core)

Does not used.