在linux中一个进程怎样生出一个子进程啊 ，请各位高手指教

两进程的程序，父进程循环显示parent,子进程循环显示child.
#include <stdio.h>                     
main()                                 
{                                       
    int pid，i;                          
    while((pid=fork())==-1);               
    if(pid!=0)                              
    {                                       
        while(1)                              
        {                 
            for(i=0;i<20;i++);           
            printf("parent");                  
        }                                       
    }                                       
    else                                    
    {                                      
        while(1)
        {        
            for(i=0;i<20;i++);  
            printf("child");           
        }                           
 }                                      
}

进程的创建是COPY过来的 COPY的父进程，然后将生成的进程分配唯一的进程ID，更改进程描述符，就成了一个新的进程