nginx停止的時候，出現了如下錯誤
nginx: [error] open() "/export/servers/nginx/logs/nginx.pid" failed (2: No such file or directory)
原因是把nginx進程殺死后pid丟失了，下一次再開啟nginx，使用 -s reload找不到pid文件。
解決辦法，參考
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)
於是我用了這方法，也就是nginx -c /path/to/config/file
在我機器上是這樣的/export/server/nginx/sbin/nginx -c /export/server/nginx/conf/nginx.conf