使用ps命令查看nginx进程的准确启动时间与启动后到现在所消耗的时间：

[hadoop@DSJ-4G-26 ~]$ ps -eo pid,lstart,etime,cmd |grep nginx
 2204 Tue Nov 21 16:52:47 2017 433-16:44:00 nginx: master process /usr/sbin/nginx
 2205 Tue Nov 21 16:52:47 2017 433-16:44:00 nginx: worker process

其中，lstart与etime的解释为：

       lstart      STARTED   time the command started.  See also bsdstart, start, start_time, and stime.

       etime       ELAPSED   elapsed time since the process was started, in the form [[DD-]hh:]mm:ss.

即nginx进程启动的时间为：2017.11.21 16:52:47，从启动到现在所消耗的时间为：433天16个小时44分钟。

参考网址：

https://www.cnblogs.com/weifeng1463/p/8807849.html?tdsourcetag=s_pctim_aiomsg