php預定義變量 （超全局變量）

服務器變量 $_SERVER //count() 34個根據url地址不同，數量有變化

    [REQUEST_URI] => /data1.php
    [DOCUMENT_ROOT] => /var/www/new.so.xywy.com
    [SERVER_PROTOCOL] => HTTP/1.1
    [GATEWAY_INTERFACE] => CGI/1.1
    [SERVER_SOFTWARE] => nginx/1.10.1
    [SERVER_ADDR] => 127.0.0.1
    [HTTP_USER_AGENT] => Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/50.0.2661.102 Chrome/50.0.2661.102 Safari/537.36

http get變量$_GET
http post變量$_POST
request 變量$_REQUEST
環境變量$_ENV
全局變量$_GLOBALS
http文件上傳變量$_FILES
http cookies$_COOKIE
session變量$_SESSION