[emerg] 28713#28713: open() "/var/run/nginx.pid" failed (13: Permission denied)

Problem 1. nginx: [alert] could not open error log file: open() "/var/log/nginx/error.log" failed (13: Permission denied)

Problem 2:  [warn] 28175#28175: the "user" directive makes sense only if the master process runs with super-user privileges, ignored in /etc/nginx/nginx.conf:1

Solution to Problem 2: You can start nginx by this command: sudo service nginx start (You might have started nginx a wrong way by: sudo systemctl start nginx)