[root@localhost ~]# journalctl -xe
Jan 29 localhost 10:39:20  nginx[8556]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Jan 29 localhost 10:39:20  nginx[8556]: nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Address already in use)
Jan 29 localhost 10:39:20  nginx[8556]: nginx: [emerg] still could not bind()
Jan 29 localhost 10:39:20  systemd[1]: nginx.service: control process exited, code=exited status=1
Jan 29 localhost 10:39:20  systemd[1]: Failed to start The nginx HTTP and reverse proxy server.

 

说明80端口被占用，杀掉这个进程：
[root@localhost ~]# killall -9 nginx

再次启动nginx：
[root@localhost ~]# /usr/local/nginx/sbin/nginx
查看是否启动：
[root@localhost ~]# ps aux|grep nginx