Bash How to Measure Execution Time

The command “time” report an execution time information

time sleep 1

Output:
real 0m1.001s
user 0m0.000s
sys 0m0.001s

Description:

Real-time from start to finish
User – the amount of CPU time spent in use mode. It is the actual CPU time used in executing the process
Sys – the amount of CPU time spent in kernel

You can measure execution time by subtraction start date and end date:

start=`date +%s`
commands...
end=`date +%s`
echo Execution time was `expr $end - $start` seconds.

If you need to have more accurate measures:

start=`date +%s%N`
commands...
end=`date +%s%N`
echo Execution time was `expr $end - $start` nanoseconds.

Adding %N to date +%s causes nanosecond accuracy.