#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
typedef struct{
	char name[4];
	int  age;
}people;
main(int argc, char** argv) {
	int fd,i;
	people *p_map;
	char temp;
	fd=open(argv[1],O_CREAT|O_RDWR|O_TRUNC,00777);
	lseek(fd,sizeof(people)*5-1,SEEK_SET);
	write(fd,"",1);
	p_map=(people*)mmap( NULL,sizeof(people)*10,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0 );
	close( fd );
	temp = 'a';
	for(i=0; i<10; i++)
	{
		temp += 1;
		memcpy( ( *(p_map+i) ).name, &temp,2 );
		( *(p_map+i) ).age = 20+i;
	}
	printf(" initialize over \n ")；
	sleep(10);
	munmap( p_map, sizeof(people)*10 );
	printf( "umap ok \n" );
}