nginx: [error] open() "/var/run/nginx.pid" failed (2: No such file or directory)

Nginx 启动时报错：nginx: [error] open() "/var/run/nginx.pid" failed (2: No such file or directory)
缘由：系统重启 /var/run/ 目录下文件会清空。

方法一：
# sudo nginx -c /etc/nginx/nginx.conf
# nginx -s reload

方法二：
修改配置文件中pid 的位置：