There are at least several ways to determine when the process was started to help you investigate and trace potential issues. I will briefly introduce four different methods to choose the most useful one.
The first method is to print the last modification time of the process directory inside proc filesystem.
$ stat --printf="%y\n" /proc/2326 2016-10-06 08:21:42.451264052 +0000
The second method is to print the time the command started using ps utility.
$ ps -p 2326 -o lstart= Thu Oct 6 08:21:42 2016
The third method is to use seconds that elapsed since the process started to calculate the time the command started.
$ date --date "now - $(ps -p 2326 -o etimes=) seconds" Thu Oct 6 08:21:42 UTC 2016
The fourth method uses clock ticks that elapsed between system boot and process execution to calculate the time the command started.
This method is suited for systems using at least Linux kernel 2.6 as the value retrieved from the process status information file was expressed earlier differently.
$ date --date "now - $(cut -d " " -f 1 /proc/uptime) seconds + $(awk '{print int($22/'$(perl -e "use POSIX;print sysconf(_SC_CLK_TCK);")')}' /proc/2326/stat) seconds"
Thu Oct 6 08:21:42 UTC 2016
Please read ps(1) and proc(5) manual pages to get a better understanding of executed commands.
