time [options] command [arguments...]
The time command runs the specified program command with the given
arguments. When command finishes, time writes a message to standard
error giving timing statistics about this program run. These statis-
tics consist of (i) the elapsed real time between invocation and termi-
nation, (ii) the user CPU time (the sum of the tms_utime and tms_cutime
values in a struct tms as returned by times(2)), and (iii) the system
CPU time (the sum of the tms_stime and tms_cstime values in a struct
tms as returned by times(2)).
Note: some shells (e.g., bash(1)) have a built-in time command that
provides less functionality than the command described here. To access
the real command, you may need to specify its pathname (something like
/usr/bin/time).