text: #include <sys/types.h>
  #include <unistd.h>
  #include <stdio.h>
  
  int main(int argc, char *argv[])
  {
  	int i,ret;
  	if(argc!=2)
  	{
  		printf("Usage %s num\n",argv[0]);
  		exit(1);
  	}
  	i=atoi(argv[1]);
  	printf("Before uid = %d ,euid = %d \n",getuid(),geteuid());
  	ret=setuid(i);
  	printf("After uid = %d ,euid =%d\n",getuid(),geteuid());
  	printf("ret=%d\n",ret);
  }
  
  
  
  