Determine the execution time of a command (UNIX)
The time utility and the time shell built-in determine the execution time of command, which must be specified. When execution of command is complete, the time utility displays the total elapsed time for execution, the time spent in the system, and the time spent in executing command. Times are reported in hours, minutes, and seconds.
Times aren't always accurate to the milliseconds as displayed, depending on the tick size.
Time the execution of dcheck -b2048 /dev/hd0:
time dcheck -b2048 /dev/hd0
The time utility exits with the exit status of the command that was timed.