Nginx 虚拟主机在配置的时候，php需要配置cgi来做相应的解析，其中有个参数fastcgi_param，原先设置为

fastcgi_param  SCRIPT_FILENAME  /usr/local/Cellar/nginx/1.12.0_1/html$fastcgi_script_name; 

导致虚拟主机在解析php县骨干文件的时候都是去www的根目录去进行定位，导致出现404的问题，后来修改为：

fastcgi_param  SCRIPT_FILENAME $document_root$fastcgi_script_name;

解决了这个问题。

完整配置文件如下：

#user  nobody;
worker_processes  1;

#error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  info;

#pid        logs/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       mime.types;
    default_type  application/octet-stream;

    #log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
    #                  '$status $body_bytes_sent "$http_referer" '
    #                  '"$http_user_agent" "$http_x_forwarded_for"';

    #access_log  logs/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    #keepalive_timeout  0;
    keepalive_timeout  65;

    #gzip  on;

    server {
        listen       8080;
        server_name  localhost;

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

        location / {
            root   html;
            index  index.php index.html index.htm;
        }

        #error_page  404              /404.html;

        # redirect server error pages to the static page /50x.html
        #
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }

        # proxy the PHP scripts to Apache listening on 127.0.0.1:80
        #
        #location ~ \.php$ {
        #    proxy_pass   http://127.0.0.1;
        #}

        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
        #
        # location ~ \.php$ {
        #     root           html;
        #     fastcgi_pass   127.0.0.1:9000;
        #     fastcgi_index  index.php;
        #     fastcgi_param  SCRIPT_FILENAME  /usr/local/Cellar/nginx/1.12.0_1/html$fastcgi_script_name;
        #     include        /usr/local/etc/nginx/fastcgi_params;
        # }

        # deny access to .htaccess files, if Apache's document root
        # concurs with nginx's one
        #
        #location ~ /\.ht {
        #    deny  all;
        #}
    }

    # another virtual host using mix of IP-, name-, and port-based configuration
    
    server {
        listen       80;
        server_name  www.demo.com;

        location / {
            root   /usr/local/var/www/www.demo.com;
            index  index.php index.html index.htm;
        }
        location ~ \.php$ {
            root           /usr/local/var/www/www.demo.com;
            fastcgi_pass   127.0.0.1:9000;
            fastcgi_index  index.php;
            fastcgi_param  SCRIPT_FILENAME $document_root$fastcgi_script_name;
            include        /usr/local/etc/nginx/fastcgi_params;
        }
    }

    # another virtual host using mix of IP-, name-, and port-based configuration
    
    server {
        listen       80;
        server_name  www.test.com;

        location / {
            root   /usr/local/var/www/www.test.com;
            index  index.php index.html index.htm;
        }
        location ~ \.php$ {
            root           /usr/local/var/www/www.test.com;
            fastcgi_pass   127.0.0.1:9000;
            fastcgi_index  index.php;
            fastcgi_param  SCRIPT_FILENAME $document_root$fastcgi_script_name;
            include        /usr/local/etc/nginx/fastcgi_params;
        }
    }


    # HTTPS server
    #
    #server {
    #    listen       443 ssl;
    #    server_name  localhost;

    #    ssl_certificate      cert.pem;
    #    ssl_certificate_key  cert.key;

    #    ssl_session_cache    shared:SSL:1m;
    #    ssl_session_timeout  5m;

    #    ssl_ciphers  HIGH:!aNULL:!MD5;
    #    ssl_prefer_server_ciphers  on;

    #    location / {
    #        root   html;
    #        index  index.html index.htm;
    #    }
    #}
    include servers/*;
}