关闭防火墙
systemctl stop firewalld
systemctl disable firewalld

安装nginx
yum install nginx

启动nginx
service nginx start

nginx默认配置文件路径
/etc/nginx/nginx.conf

nginx默认配置文件内容

# For more information on configuration, see:
#   * Official English Documentation: http://nginx.org/en/docs/
#   * Official Russian Documentation: http://nginx.org/ru/docs/

user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;

# Load dynamic modules. See /usr/share/nginx/README.dynamic.
include /usr/share/nginx/modules/*.conf;

events {
    worker_connections 1024;
}

http {
    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  /var/log/nginx/access.log  main;

    sendfile            on;
    tcp_nopush          on;
    tcp_nodelay         on;
    keepalive_timeout   65;
    types_hash_max_size 2048;

    include             /etc/nginx/mime.types;
    default_type        application/octet-stream;

    # Load modular configuration files from the /etc/nginx/conf.d directory.
    # See http://nginx.org/en/docs/ngx_core_module.html#include
    # for more information.
    include /etc/nginx/conf.d/*.conf;

    server {
    listen       80 default_server;
    listen       [::]:80 default_server;
    server_name  _;
    root         /usr/share/nginx/html;

    # Load configuration files for the default server block.
    include /etc/nginx/default.d/*.conf;

    location / {
    }

    error_page 404 /404.html;
        location = /40x.html {
    }

    error_page 500 502 503 504 /50x.html;
        location = /50x.html {
    }
    }

# Settings for a TLS enabled server.
#
#    server {
#        listen       443 ssl http2 default_server;
#        listen       [::]:443 ssl http2 default_server;
#        server_name  _;
#        root         /usr/share/nginx/html;
#
#        ssl_certificate "/etc/pki/nginx/server.crt";
#        ssl_certificate_key "/etc/pki/nginx/private/server.key";
#        ssl_session_cache shared:SSL:1m;
#        ssl_session_timeout  10m;
#        ssl_ciphers HIGH:!aNULL:!MD5;
#        ssl_prefer_server_ciphers on;
#
#        # Load configuration files for the default server block.
#        include /etc/nginx/default.d/*.conf;
#
#        location / {
#        }
#
#        error_page 404 /404.html;
#            location = /40x.html {
#        }
#
#        error_page 500 502 503 504 /50x.html;
#            location = /50x.html {
#        }
#    }

}

查看nginx启动了多久
ps -p cat /run/nginx.pid -o etime=

测试，在/etc/nginx/conf.d/添加新的server app1, app2
server {

        listen 80;
        servername app1.com www.app1.com;
        location / {
            root /usr/share/nginx/html/app1;
        }
    }

    server {

        listen 80;
        servername app2.com www.app2.com;
        location / {
            root /usr/share/nginx/html/app2;
        }
    }

    在创建/usr/share/ngin/html 下创建 app1/index.html 和 app2/index.html
    重启nginx:  nginx -s reload
    访问172.16.20.79 默认app1.com， 再访问app1.com 和 app2.com

修改端口,跳到默认default_server或者顺序第一个可以提供服务的server
    在 app2.com的server配置中，在listen 80后面加 default_server ,然后访问172.16.20.79，页面显示app2.com
    如果不希望相应没有host HTTP头的，添加下面的配置
    server {
        listen 80;
        server_name "" localhost 127.0.0.1 172.16.20.79;
        return 444;  # 不响应，并关闭连接
    }

Location参数
最长匹配原则
~* 不分大小写匹配
~ 区分大小写匹配
^~ uri如果开头等于这个值，不再尝试正则匹配
= 精准匹配，将常用URL用这个写法，可以提供性能，因为nginx不需要进行搜索