之前按騰訊雲的教程 在 /etc/nginx/conf.d/default.conf 修改配置後，啟動nginx時報錯：

nginx: [emerg] a duplicate default server for 0.0.0.0:80 in /etc/nginx/nginx.conf:39

然後我修改了/etc/nginx/nginx.conf配置為

# 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 /var/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;
}
 

然後啟動nginx服務，如果提示

nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
nginx: [emerg] still could not bind()

那麼就是80埠有服務佔用了，那就找到80端口占用的程序殺掉即可。

檢視80埠的程序命令：

lsof -i :80

當時我顯示的是

COMMAND  PID  USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
nginx   3905  root    6u  IPv4 2561830      0t0  TCP *:http (LISTEN)
nginx   3905  root    7u  IPv6 2561831      0t0  TCP *:http (LISTEN)
nginx   3906 nginx    6u  IPv4 2561830      0t0  TCP *:http (LISTEN)
nginx   3906 nginx    7u  IPv6 2561831      0t0  TCP *:http (LISTEN)
 

所以大概是因為我重複開了nginx，你想重新開就殺掉這幾個程序就行，使用命令

kill -9 3905
kill -9 3906

就是kill -9 加上程序號（PID）

OK，重新開啟nginx

成功！