[問題] 用app 執行底層的 shell command

[blueblueChen (藍藍欠)]

今天試了一整天，有點崩潰..開發環境 Android studio 2.1，試了網路上範例
device 是 nexus 6P 安卓7.0

onCreate(){

  TextView tex = (TextView)findViewById(R.layout.textView);

  try {
        execCommand("ls");

   } catch (IOException e) {
              // TODO Auto-generated catch block
              e.printStackTrace();
  }
}

public void execCommand(String command) throws IOException {

        Runtime runtime = Runtime.getRuntime();
        Process proc = runtime.exec(command);
        try {
            if (proc.waitFor() != 0) {
                System.err.println("exit value = " + proc.exitValue());
            }
            BufferedReader in = new BufferedReader(new InputStreamReader(
                    proc.getInputStream()));

            StringBuffer stringBuffer = new StringBuffer();

            String line = null;

            while ((line = in.readLine()) != null) {
                stringBuffer.append(line+"-");
            }
            tex.setText(stringBuffer.toString());

        } catch (InterruptedException e) {
            System.err.println(e);
        }
    }

他可以印出執行完 "ls"後的字串，並展示在 app 上，其他

cat /proc/sys/net/ipv4/ip_forward 也可以展示出來

-----------------------------------------------------------------------------

可我想要寫入 echo 0 > /proc/sys/net/ipv4/ip_forward 卻一直無法成功，以下是 code

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        try {
            execCommand("echo 0 > /proc/sys/net/ipv4/ip_forward\n");
        }
        catch(IOException e){
            e.printStackTrace();
        }
}//end onCreate

public void execCommand(String command) throws IOException {

       java.lang.Process  su = Runtime.getRuntime().exec(command);
       DataOutputStream outputStream = new
       DataOutputStream(su.getOutputStream());
       outputStream.writeBytes("echo 0 > /proc/sys/net/ipv4/ip_forward\n");

       outputStream.writeBytes("exit\n");
       outputStream.flush();
    }

------------------------------------------------------------------------------

另外的嘗試是依樣以上面的程式範例

execCommand("echo 0 > /proc/sys/net/ipv4/ip_forward\n");

改成

execCommand("su");

Android studio 出現以下 error:

W/System.err: java.io.IOException: Cannot run program "su":
error=13, Permission denied

com.example.user.myapplication W/System.err:
  at java.lang.ProcessBuilder.start(ProcessBuilder.java:983)

com.example.user.myapplication W/System.err:
  at java.lang.Runtime.exec(Runtime.java:691)

com.example.user.myapplication W/System.err:
  at java.lang.Runtime.exec(Runtime.java:524)

com.example.user.myapplication W/System.err:
  at java.lang.Runtime.exec(Runtime.java:421)

com.example.user.myapplication W/System.err:
  at
com.example.user.myapplication.MainActivity.execCommand(MainActivity.java:41)

com.example.user.myapplication W/System.err:
  at
com.example.user.myapplication.MainActivity.onCreate(MainActivity.java:33)
com.example.user.myapplication W/System.err:
  at android.app.Activity.performCreate(Activity.java:6664)

com.example.user.myapplication W/System.err:
  at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
com.example.user.myapplication W/System.err:
  at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)

com.example.user.myapplication W/System.err:
  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)

com.example.user.myapplication W/System.err:
  at android.app.ActivityThread.-wrap12(ActivityThread.java)

com.example.user.myapplication W/System.err:
  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)

com.example.user.myapplication W/System.err:
  at android.os.Handler.dispatchMessage(Handler.java:102)

com.example.user.myapplication W/System.err:
  at android.os.Looper.loop(Looper.java:154)

com.example.user.myapplication W/System.err:
  at android.app.ActivityThread.main(ActivityThread.java:6077)

com.example.user.myapplication W/System.err:
  at java.lang.reflect.Method.invoke(Native Method)

com.example.user.myapplication W/System.err:
  at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)

com.example.user.myapplication W/System.err:
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)

com.example.user.myapplication W/System.err:
Caused by: java.io.IOException: error=13, Permission denied

com.example.user.myapplication W/System.err:
  at java.lang.UNIXProcess.forkAndExec(Native Method)

com.example.user.myapplication W/System.err:
  at java.lang.UNIXProcess.<init>(UNIXProcess.java:133)

com.example.user.myapplication W/System.err:
  at java.lang.ProcessImpl.start(ProcessImpl.java:128)

com.example.user.myapplication W/System.err:
  at java.lang.ProcessBuilder.start(ProcessBuilder.java:964)

com.example.user.myapplication W/System.err:
        ... 17 more


可以編譯，可以看到手機上有app



請大俠指教...

萬分感激，謝謝。


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※ 文章網址: https://www.ptt.cc/bbs/AndroidDev/M.1477211618.A.646.html
※ 編輯: blueblueChen (58.115.110.28), 10/23/2016 16:41:41
→ ssccg: 你有權限?
→ blueblueChen: 請問您指的權限是?
※ 編輯: blueblueChen (58.115.110.28), 10/23/2016 17:15:44
→ blueblueChen: 我在AndroidManifest.xml加上
→ blueblueChen: <uses-permission android:name="android.permissio
→ blueblueChen: n.ACCESS_SUPERUSER"/> 結果相同...
→ y3k: 你沒有用過Linux吧? 第一次的問題是你沒要系統管理員權限
→ y3k: 第二次是你要了但是拿不到 第三次(你剛剛的推文)是你的系統不
→ y3k: 給你 簡單講 這種code必須要在"root過"的手機上才能跑
→ blueblueChen: 您好，我聽了各位的話...root nexus 6p 手機
→ blueblueChen: 然後他就可以了!  只是我很那悶，我在還沒root時
→ blueblueChen: 就已經看到 system/xbin/su 有這個檔案了，為啥我還
→ blueblueChen: 需要 root tool??
→ KeySabre: 樓上已經有人說出你該補的觀念囉