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Demo

Here's demo application called "Run Native Exe" to:

Package: NativeExe-0.2.apk
Source code: on Github (ADT project)

To install the package,

or type "adb install NativeExe?-*.apk" in your PC if you have Android SDK.

How can I run UNIX commands in Android App?

You can use Runtime.exec() in standard Java. Here's sample code to run /system/bin/ls /sdcard in Android App:

try {
    // Executes the command.
    Process process = Runtime.getRuntime().exec("/system/bin/ls /sdcard");
    
    // Reads stdout.
    // NOTE: You can write to stdin of the command using
    //       process.getOutputStream().
    BufferedReader reader = new BufferedReader(
            new InputStreamReader(process.getInputStream()));
    int read;
    char[] buffer = new char[4096];
    StringBuffer output = new StringBuffer();
    while ((read = reader.read(buffer)) > 0) {
        output.append(buffer, 0, read);
    }
    reader.close();
    
    // Waits for the command to finish.
    process.waitFor();
    
    return output.toString();
} catch (IOException e) {
    throw new RuntimeException(e);
} catch (InterruptedException e) {
    throw new RuntimeException(e);
}

This code is based on this article. Thanks yussi to let me know this by comment.

OK, but how can I put my own native executable in Android App?

First, you need to cross-compile your native executable for ARM. Here's a way (dynamic link version). Or you can use Scratchbox (Japanese). If you get a file with a format like this, it's probably OK:

% file yourapp
yourapp: ELF 32-bit LSB executable, ARM, version 1 (SYSV), for GNU/Linux 2.6.14, statically linked, not stripped

You have three ways to put the binary to the phone:

Old way which no longer works

This code doesn't work on Android 2.3 (and probably 2.2).

try {
    // android.os.Exec is not included in android.jar so we need to use reflection.
    Class<?> execClass = Class.forName("android.os.Exec");
    Method createSubprocess = execClass.getMethod("createSubprocess",
            String.class, String.class, String.class, int[].class);
    Method waitFor = execClass.getMethod("waitFor", int.class);
    
    // Executes the command.
    // NOTE: createSubprocess() is asynchronous.
    int[] pid = new int[1];
    FileDescriptor fd = (FileDescriptor)createSubprocess.invoke(
            null, "/system/bin/ls", "/sdcard", null, pid);
    
    // Reads stdout.
    // NOTE: You can write to stdin of the command using new FileOutputStream(fd).
    FileInputStream in = new FileInputStream(fd);
    BufferedReader reader = new BufferedReader(new InputStreamReader(in));
    String output = "";
    try {
        String line;
        while ((line = reader.readLine()) != null) {
            output += line + "\n";
        }
    } catch (IOException e) {
        // It seems IOException is thrown when it reaches EOF.
    }
    
    // Waits for the command to finish.
    waitFor.invoke(null, pid[0]);
    
    return output;
} catch (ClassNotFoundException e) {
    throw new RuntimeException(e.getMessage());
} catch (SecurityException e) {
    throw new RuntimeException(e.getMessage());
} catch (NoSuchMethodException e) {
    throw new RuntimeException(e.getMessage());
} catch (IllegalArgumentException e) {
    throw new RuntimeException(e.getMessage());
} catch (IllegalAccessException e) {
    throw new RuntimeException(e.getMessage());
} catch (InvocationTargetException e) {
    throw new RuntimeException(e.getMessage());
}

This code is based on source code of Android Terminal Emulator.

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