This code snippet creates the shortcode "sel" under WordPress to automatically search for the surrounded words. The search engine can be defined by an argument. With no argument the search own your own WP site is used. The snippet needs to be included in the functions.php of the WordPress theme.

wp_shortcode_sel.php

<?php

/*

Usage: [sel engine=ddg|bing|google]word1 word2 ...[/sel]   
 
"ddg": DuckDuckGo   
"bing": Bing   
"google": Google   
"": Site Search (Default)

*/

function search_engine_links ( $atts, $content = null ) {
	
	extract(shortcode_atts(array(
		"engine" => ''
	), $atts));
	
	switch ($engine) {
		case "ddg": // DuckDuckGo
			$search_str = "https://duckduckgo.com/?q=";
			break;
		case "bing": // Bing
			$search_str = "http://www.bing.com/search?q=";
			break;
		
		case "google": // Google
			$search_str = "http://www.google.de/search?q=";
			break;
		default: // your own WP site, replace with your own domain
			$search_str = "http://www.acky.de/?s=";
			break;
	}
	
	return '<a href="' . $search_str . do_shortcode(urlencode($content)) . '">' . do_shortcode($content) . '</a>';
}

if ( function_exists('add_shortcode') ) {
	add_shortcode('sel', 'search_engine_links');
}

?>