设计并实现Unix的“time”命令。“mytime”命令通过命令行参数接受要运行的程序，创建一个独立的进程来运行该程序，并记录程序运行的时间。-Designs and implements the Unix " time"　command. " Mytime"　command from the command line parameters to accept the program you want to run, create a separate process to run the program, and record the time the program runs.