体会exec函数用法

#include<sys/types.h>
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
int main()
{
//      if((execl("/bin/ls","ls","-all","/home",NULL))<0)
//              printf("execl error\n");
        if((execle("/bin/ls","ls","-all","/home",(char *)NULL,(const char *)NULL))<0)
                printf("execle error\n");
//      if((execlp("ls","ls","-all","/home",(char *)NULL))<0)
//              printf("execlp error\n");


}