Get program execution time in the shell?

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

There is actual a builtin command in BASH called time, which takes another command as an argument and returns the execution time. NOTE: If the time is too small to measure it may just list as 0.

For example:

jake@Mia-Arch:/tmp$ cd WyzantDemo/

jake@Mia-Arch:/tmp/WyzantDemo$ time pwd

/tmp/WyzantDemo

real 0m0.000s

user 0m0.000s

sys 0m0.000s

jake@Mia-Arch:/tmp/WyzantDemo$

Answer 2

Yes! You can use the time command. The usage is

time program-name program-arguments

The first two numbers of output are the user time and the system time, and the third number is wall time.

Process Time is the sum of user time and kernel time.

User Time - When the OS was running your code

Kernel Time - When the OS is running system code (i.e. system calls)

Wall Time is just a timer (it runs from when your program starts to when it finishes, regardless of whether your program has to wait on other programs)

Hope this helps!