#include <stdio.h>#include <string.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#define filename "/dev/akae"int main(void){	int fd;	char buf[100];	int ret_w,ret_r;	fd = open(filename,O_RDWR);	if (fd < 0)	{		printf("open %s file error,please use sudo?",filename);		return -1;	}	//while (1)	{		fgets(buf,100,stdin);		printf("buf1 = %s\n",buf);		ret_w = write(fd,buf,strlen(buf));		printf("ret_w = %d,buf2 = %s\n",ret_w,buf);		ret_r = read(fd,buf,ret_w);		printf("ret_r = %d,buf3 = %s\n",ret_r,buf);	}	close(fd);	return 0;}