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。在Linux下实现:

◦ 使用fork()/execv()来创建进程运行程序

◦ 使用wait()等待新创建的进程结束

◦ 调用gettimeofday()来获取时间

-Design and implementation of Unix " time"　command. " Mytime"　command from the command line arguments accepted to run the program, create a separate process to run the program, and record the program running time. In the Linux implementation: ◦　Use fork ()/execv () to create a process to run the program ◦　Use wait () to wait for the end of the newly created process ◦　call gettimeofday () to get the time