readStream.isRaw

boolean类型，如果 TTY 当前配置为作为原始设备操作，则为 true。

【A boolean that is true if the TTY is currently configured to operate as a raw device.】

当进程启动时，该标志总是 false，即使终端处于原始模式。其值会随着后续对 setRawMode 的调用而改变。

【This flag is always false when a process starts, even if the terminal is operating in raw mode. Its value will change with subsequent calls to setRawMode.】