Shell script gets the running time of the process _linux shell

In our system, I wrote a script to update some repository on a regular basis, but occasionally I encountered problems, such as when git pull might be stuck there (possibly due to a network problem at some point), which would hinder the next update.
So I thought, when I started this script, I would check it and kill it and its subprocess if the last script I ran was not finished and a certain time threshold was passed. Then I need to write a script that can query how much time (in second) a process has been running.
Note: This does not refer to the CPU time consumed by the process, which is the current time minus the time at which the process started, and this is the time period.

Originally, PS itself also provides the option to query, but more intuitive and image (such as 10:32), not seconds as a unit, is not convenient to use in the script directly. The commands for process time in PS are as follows:

Copy Code code as follows:

[Root@jay-linux jay]# ps-p 4260-o Pid,start_time,etime,comm
PID START ELAPSED COMMAND
4260 Apr18 16-08:57:25 gnome-session

The third column of 16-08:57:25 is the time the process runs: 16 days, 8 hours, 57 minutes and 25 seconds.

I myself based on some information in the/proc file system, the query process run time script is shared as follows:

Copy Code code as follows:

#!/bin/bash
function Show_elapsed_time ()
{
user_hz=$ (getconf clk_tck) #mostly it ' s on x86/x86_64
Pid=$1
jiffies=$ (cat/proc/$pid/stat | cut-d ""-f22)
sys_uptime=$ (Cat/proc/uptime | cut-d ""-F1)
last_time=$ ((${sys_uptime%.*}-$jiffies/$user _hz))
echo "The process $pid lasts for $last _time seconds."
}

If [$#-ge 1];then
For PID in $@
Todo
Show_elapsed_time $pid
Done
Fi

While read PID
Todo
Show_elapsed_time $pid
Done

The implementation process and results are as follows:

Copy Code code as follows:

[Root@jay-linux jay]#./get_process_time.sh 4260
The process #4260 lasts for 1415417 seconds.

Follow-up I write two more simple talk about/proc/stat,/proc/$pid/stat,/proc/uptime Bar.