PHP statistics search engine crawling 404 link page path in nginx access log_PHP tutorial

//Visit test.php?s=google
$domain='http://www.jb51.net';
$spiders=array('baidu'=>'Baiduspider','360'=>'360Spider',
'google'=>'Googlebot','soso'=>'Sosospider','sogou'=>
'Sogou web spider','easou'=>'EasouSpider','bing'=>'bingbot');

$path='/home/nginx/logs/'.date('Y/m/').(date('d')-1).'/access_www.txt';

$s=$_GET['s'];

if(!array_key_exists($s,$spiders)) die();
$spider=$spiders[$s];

$file=$s.'_'.date('ym').(date('d')-1).'.txt';
if(!file_exists($file)){
$in=file_get_contents($path);
$pattern='/GET (.*) HTTP/1.1" 404.*'.$spider.'/';
Preg_match_all ( $pattern , $in , $matches );
$out='';
foreach($matches[1] as $k=>$v){
          $out.=$domain.$v."rn";
}
File_put_contents($file,$out);
}

$url=$domain.'/silian/'.$file;
echo $url;