现象：
[root@server1 nginx-1.17.4]# /usr/local/nginx/sbin/nginx
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: [emerg] still could not bind()
原因：
查看报错原因：说是80端口已经被使用
解决方法：
关闭80端口
[root@server1 nginx-1.17.4]# fuser -k 80/tcp
80/tcp: 2145 2146 2147 2148 2149 2150
然后启动nginx启动成功～～～～
