+ char read_out[256];
+
+ // 切换工作目录至 /dev
+ int errno = chdir("/dev");
+ if (errno) {
+ write(STDOUT, "fail to chdir", 15);
+ return;
+ }
+
+ if (getcwd(read_out, sizeof(read_out))) {
+ write(STDOUT, "current working dir: ", 22);
+ write(STDOUT, read_out, 256);
+ write(STDOUT, "\n", 2);
+ }
+
+ // sda 设备 - 硬盘
+ // sda设备属于容积设备(Volumetric Device),
+ // Lunaix会尽可能缓存任何对此设备的上层读写,并使用延迟写入策略。(FO_DIRECT可用于屏蔽该功能)
+ int fd = open("./sda", 0);