当安装完最新版的nginx和最新版的PHP以后，使用niginx默认配置文件中的PHP配置会有错误
访问指定目录下的php文件时，显示File not found.错误。查看nginx的错误日志显示

90#90: *1 FastCGI sent in stderr: "Primary script unknown" while reading response header from upstream, client: 127.0.0.1, server: 127.0.0.1, request: "GET /index.php HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "127.0.0.1"

排查的过程：
1.修改默认PHP配置中的fastcgi_param配置fastcgi_param配置，这个地方默认的是/Scripts$fastcgi_script_name

fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;

2.把root指令从location /{}块里面拿到外面，因为看fpm的access日志，访问PHP文件报的404错误

最简配置如下：

server {
    listen       80;
    server_name  127.0.0.1;
    access_log  /var/log/nginx/default.access.log  main;
    error_log /var/log/nginx/default.error.log;
    root   /var/www/html;
    location / {
        index  index.html index.htm;
    }
    location ~ \.php$ {
        fastcgi_pass   127.0.0.1:9000;
        fastcgi_index  index.php;
        fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
        include        fastcgi_params;
    }
}