我的nginx服务器无法启动时遇到问题。具有相应知识的人是否可以尝试诊断我的错误代码，并就如何解决我的问题给我一些指导？这是我第一次发帖，所以如果您需要更多信息，请告诉我。谢谢（：
michael@productionserver1:~$ sudo systemctl start nginx
Job for nginx.service failed because the control process exited with error code. See "systemctl status nginx.service" and "journalctl -xe" for details.
michael@productionserver1:~$ systemctl status nginx.service
● nginx.service - A high performance web server and a reverse proxy server
Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Thu 2016-07-14 05:50:29 EDT; 16s ago
Process: 3754 ExecStop=/sbin/start-stop-daemon --quiet --stop --retry QUIT/5 --pidfile /run/
Process: 2269 ExecReload=/usr/sbin/nginx -g daemon on; master_process on; -s reload (code=ex
Process: 3598 ExecStart=/usr/sbin/nginx -g daemon on; master_process on; (code=exited, statu
Process: 5641 ExecStartPre=/usr/sbin/nginx -t -q -g daemon on; master_process on; (code=exit
Main PID: 3600 (code=exited, status=0/SUCCESS)
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我在运行“nginx -t”nginx: [alert] could not open error log file: open() "/var/log/nginx/error.log" failed: (13 Permission denied) 2016/07/14 07:32:23 [warn] 6060#6060: the "user" directive makes sense only if the master process runs with super-suer privileges, ignored in /etc/nginx/nginx.conf:1 2016/07/14 07:32:23 [emerg] 6060#6060: a duplicate default server for 0.0.0.0:44 3 in /etc/nginx/sites-enabled/example.com:34 nginx: configuration file /etc/nginx/nginx.conf text failed