Performance and Benchmarking

bash time built-in

On a bash shell session:

help time
$ help time
time: time [-p] pipeline
    Report time consumed by pipeline's execution.

    Execute PIPELINE and print a summary of the real time, user CPU time,
    and system CPU time spent executing PIPELINE when it terminates.

      -p	print the timing summary in the portable Posix format

    The value of the TIMEFORMAT variable is used as the output format.

    Exit Status:
    The return status is the return status of PIPELINE.

So, to have an idea how long a command takes we simply do time <cmd> <opts>. Some examples:

$ time sleep 5 ; echo done

real	0m5.061s
user	0m0.001s
sys	0m0.004s

$ time wget -q -O /dev/null

real	0m0.978s
user	0m0.018s
sys	0m0.016s

$ time npm ci
$ time npm cache verify
$ time nvm install < .nvmrc