Question

I want to execute something in a linux shell under a few different conditions, and be able to output the execution time of each execution.

I know I could write a perl or python script that would do this, but is there a way I can do it in the shell? (which happens to be bash)

Answer 1

Use the built-in time keyword:

 $ help time  time: time [-p] PIPELINE     Execute PIPELINE and print a summary of the real time, user CPU time,     and system CPU time spent executing PIPELINE when it terminates.     The return status is the return status of PIPELINE.  The `-p' option     prints the timing summary in a slightly different format.  This uses     the value of the TIMEFORMAT variable as the output format. 

Example:

$ time sleep 2 

 real    0m2.009s user    0m0.000s sys     0m0.004s