文件权限用八进制书描述

int main(int argc, char *argv[])
{
        char data[] = "hello you are handsome!!\n";
        char buffer[20];
        int fd;
        if(argc < 2)
        {
                printf("input pathname!\n");
                exit(1);
        }
        if((fd = open(argv[1], O_CREAT|O_RDWR,0666)) < 0) // 此处0666为八进制，所以改成666执行结果错误！
        { printf("open failure\n");
                exit (1);
        }

        close（fd）;

        return 0;

}