nginx停止的时候，出现了如下错误

nginx: [error] open() "/export/servers/nginx/logs/nginx.pid" failed (2: No such file or directory)

原因是把nginx进程杀死后pid丢失了，下一次再开启nginx，使用 -s reload找不到pid文件。

解决办法，参考

http://blog.csdn.net/jk0803_wantao/article/details/9468535

ginx -s reload is only used to tell a running nginx process to reload its config. After a stop, you don't have a running nginx process to send a signal to. Just run nginx (possibly with a -c /path/to/config/file)

于是我用了这方法，也就是nginx -c /path/to/config/file

在我机器上是这样的/export/server/nginx/sbin/nginx -c /export/server/nginx/conf/nginx.conf