- preg_match: documentation ( source)
<?php
$agent = 'Dotbot';
if ($agent=='' || preg_match('#(megaupload|feedfetcher|yisouspider|httrack|httpclient|surveybot|anonymous|similarpages|webcollage|mj12bot|webcopier|teleport|ispider|wget|offline|websnake|download|ezooms|exabot|gigabot|dotbot|psbot)#i',$agent))
echo 1;
else
echo 0;