get elapsed time in bash I would like to do the following at one point in a script: start_time=date and this after a process or processes have run: end_time=date and then do this: elapsed=$end_time-$start_time echo "Total of $elapsed seconds elapsed for process" How would I do this?

Use the time since epoch to easily identify a span of time in a script


man date
%s seconds since 1970-01-01 00:00:00 UTC
%N nanoseconds (000000000..999999999)


.


start_time="$(date -u +%s)"
sleep 5
end_time="$(date -u +%s)"

elapsed="$(($end_time-$start_time))"
echo "Total of $elapsed seconds elapsed for process"

Total of 5 seconds elapsed for process


* * *

Bash doesn't support floating point numbers, so you'll need to use a external tool like bc to compare times like `1475705058.042270582-1475705053.040524971`


start_time="$(date -u +%s.%N)"
sleep 5
end_time="$(date -u +%s.%N)"

elapsed="$(bc <<<"$end_time-$start_time")"
echo "Total of $elapsed seconds elapsed for process"

Total of 5.001884264 seconds elapsed for process