如何使用Runtime.getRuntime（）。exec（“ cmd”） [英] How to use Runtime.getRuntime().exec("cmd")

问题描述

在我的应用程序中，我试图执行SD卡上存在的本机代码。

In my application I'm trying to execute a native code which is present on my SD card.

File sdCard = getExternalFilesDir(null); // directory where native file is placed
String nativeFile = "nativeFile";

String cmd = "shell /system/bin/chmod 0777 " + sdCard.getAbsolutePath() + "/" + nativeFile;
Process proc = Runtime.getRuntime().exec(cmd);

但是只要 Runtime.getRuntime（）。exec（cmd）被执行，它引发错误：

But as soon as Runtime.getRuntime().exec(cmd) is executed, it throws error:

java.io.IOException: Error running exec(). Command: [shell, /system/bin/chmod, 0777, /storage/emulated/0/Android/data/com.example.andridutilproject/files/native] Working Directory: null Environment: null

任何建议，如何解决？

推荐答案

通常会禁用Android系统中的sdcard以便执行。因此，即使您正确执行chmod命令，它也会失败。

The sdcard in an Android system is usually disabled for execution. Therefore even if you correctly execute the chmod command it will fail.

您可以轻松地进行测试。通过USB启动外壳程序（adb外壳程序）并执行chmod命令。它将失败，并显示诸如错误模式之类的错误消息。

You can test that easily. Start the shell via USB (adb shell) and execute the chmod command. It will fail with an error message like "Bad mode".

因此，您必须将文件复制到具有写访问权的其他位置，然后将可执行位设置为在那个副本上。您可以尝试将文件复制到 / data / local / tmp /中，但是我不确定该路径是否仍然可用。

Therefore you have to copy the file to a different location where you have write access and then set the executable bit on that copy. You can try to copy the file for example to "/data/local/tmp/" but I am not sure if that path is still usable.

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