PHP能得到客户端的浏览器的信息吗?

PHP_SELF;
_SERVER["ALL_HTTP"] 
_SERVER["HTTPS"] 
_SERVER["SCRIPT_NAME"] 
_SERVER["CONTENT_LENGTH"] 
_SERVER["PATH_TRANSLATED"] 
_SERVER["REMOTE_ADDR"] 
_SERVER["REMOTE_HOST"] 
_SERVER["REQUEST_METHOD"] 
_SERVER["SERVER_NAME"] 
_SERVER["SERVER_PORT"] 
_SERVER["SERVER_PROTOCOL"]
_SERVER["SERVER_SOFTWARE"]
_SERVER["APPL_MD_PATH"]
_SERVER["APPL_PHYSICAL_PATH"]
_SERVER["INSTANCE_ID"]
_SERVER["INSTANCE_META_PATH"]
_SERVER["URL"]
_SERVER["PHP_SELF"]
_SERVER["HTTP_ACCEPT"] 
_SERVER["HTTP_ACCEPT_LANGUAGE"]
_SERVER["HTTP_CONNECTION"]
_SERVER["HTTP_HOST"]
_SERVER["HTTP_USER_AGENT"]
_SERVER["HTTP_ACCEPT_ENCODING"]
_SERVER["DOCUMENT_ROOT"]=====================================
使用时候 这样 echo $PHP_SELF;