#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>

int main() {
    int testdev = open("/dev/mydev", O_RDWR);
    if (testdev == -1) {
        printf("can not open file\n");
        exit(0);
    }
    char buf[50] = "pear to dev!";
    write(testdev, buf, 50);
    printf("write: %s\n", buf);
    strcpy(buf, "apple to dev!");
    read(testdev, buf, 50);
    printf("read: %s\n", buf);
    close(testdev);
    return 0;
}