$ time ls
real 0m0.005s
user 0m0.004s
sys 0m0.000s
* The elapsed (real) time between invocation of utility and its
termination.
* The User CPU time, equivalent to the sum of the tms_utime and
tms_cutime fields returned by the times() function defined in the
System Interfaces volume of IEEE Std 1003.1-2001 for the process in
which utility is executed.
* The System CPU time, equivalent to the sum of the tms_stime and
tms_cstime fields returned by the times() function for the process
in which utility is executed.
ที่มา: Time