1.启动nginx命令
./sbin/nginx
2.提示80端口被占用
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()
3.执行netstat -antp查看谁占用了80端口
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 127.0.0.1:80 127.0.0.1:34932 TIME_WAIT -
4.通过调整内核参数解决
vi /etc/sysctl.conf
编辑文件，加入以下内容：
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_fin_timeout = 30
然后执行/sbin/sysctl -p让参数生效。
5.关闭窗口断开连接，重新打开
80端口仍被占用
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 1402/nginx: master
6.kill占用80端口的进程
7./sbin/nginx
此时，启动nginx成功
执行命令 kill -9 1402
参考资料：https://blog.csdn.net/gzh0222/article/details/8491178