如何从用户应用程序中读取sysfs属性。它与cat命令类似。比如我有一个标签是亮度。我怎样才能获得亮度标签的价值？因为我需要从我的应用程序中读取USB infor，并且我看到它们被导出到sysfs，如下面的拓扑：
ls /sys/bus/usb/devices/1-1
1-1:1.0 busnum port
authorized configuration power
avoid_reset_quirk descriptors product
bConfigurationValue dev quirks
bDeviceClass devnum removable
bDeviceProtocol devpath remove
bDeviceSubClass driver serial
bMaxPacketSize0 ep_00 speed
bMaxPower idProduct subsystem
bNumConfigurations idVendor uevent
bNumInterfaces ltm_capable urbnum
bcdDevice manufacturer version
bmAttributes maxchild
答案 0 :(得分：2)
使用例如打开文件<body>
<div id="top">
<center>
<h1>High Low Card Game</h1>
</center>
</div>
<br>
<p>the rules are simple chose if the next card is high or is the card low and try to beat your own score ! ♠ ♣ ♦ ♥
</p>
<br>
<button id="test1" type="button" onclick="setTimeout( Start(), 1000000 )">
Start Game</button>
<span id="welcome"></span>
<p id="name"></p>
<br>
<span id="card"></span>
<br>
<span id="question"></span>
<br>
<span id="score"></span>
<button id="test" type="button" onclick="highOrLow('high')">
Higher</button>
<br>
<button id="test2" type="button" onclick="highOrLow('low')">
Lower</button>
<br>
<span id="high"></span>
</body>并与其他文件一样阅读其内容。不确定亮度，你没有提到它的文件，也没有该文件的文件。