How to log a process's uptime and restarts

Question

I know that I can check a process's uptime with the following:

ps -o etime= -p "PID"

where PID = pid number.

I would like to write to a log when this process ends, and include it's uptime. The exact time it exits would be nice, but not strictly necessary. I have a script which automatically restarts it, but I am looking to increase it's stability. In this case, the process is ffmpeg. I am running a very low bandwidth stream from an unstable source, and the process frequently, intermittently fails.

I feel that if I could log it for a day or two, I could try different configurations to see if I can extend the uptime to an acceptable limit.

Thank you for your valuable insight!

Answer 1

ps -eo pid,comm,lstart,etime,time,args

This command lists all processes with several different time-related columns. pipe it to grep ffmpeg to find out about the your process of interest.

The output of the previous command has the following columns:

PID COMMAND                          STARTED     ELAPSED     TIME COMMAND

according to ps man

PID = Process ID
first COMMAND = only the command name without options and without arguments
STARTED = the absolute time the process was started
ELAPSED = elapsed time since the process was started (wall clock time), format [[dd-]hh:]mm:ss TIME = cumulative CPU time, "[dd-]hh:mm:ss" format
second COMMAND = again the command, this time with all its provided options and arguments