WordPress at a glance
filter is not described

get_search_form filter-hook . WP 2.7.0

Filters the HTML output of the search form.

Usage

add_filter( 'get_search_form', 'filter_function_name_2343' );
function filter_function_name_2343( $form ){
	// filter...

	return $form;
}
$form(string)
The search form HTML output.

Where the hook is called

get_search_form()
get_search_form
wp-includes/general-template.php 235
$result = apply_filters( 'get_search_form', $form );

Where the hook is used (in WP core)

Does not used.