Android修改默认system/bin/下可执行程序拥有者和权限，使用实例，只有root和系统app权限才能执行某个命令。

一、执行ls -l /system/bin/ 查看一下用户和权限。

二、这些权限在哪里修改呢？ 默认编译system/bin/可执行程序赋予权限的地方system\core\libcutils\fs_config.cpp 文件里面的android_files

三、使用实例，只有root和系统app权限才能执行某个命令，如上面的sn_writer命令，只有系统app和root权限才能运行。

package com.giada.sn_writer;
 
import androidx.appcompat.app.AppCompatActivity;
 
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
 
public class MainActivity extends AppCompatActivity {
    private Button m_Button;
    private EditText m_EditText;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        m_Button=(Button)findViewById(R.id.button);
        m_EditText = (EditText) findViewById(R.id.textView);
 
        m_Button.setOnClickListener(new Button.OnClickListener() {
            public void onClick(View v)
            {
                String str = m_EditText.getText().toString();
                sn_writer_command("sn_writer write-key "+ str);
              //  playRunTime("sn_writer write-key "+ str);
            }
        });
 
    }
    public static String sn_writer_command(String cmd) {
        try {
            //String keyCommand = "setprop " + propName;
            Runtime runtime = Runtime.getRuntime();
            Process proc = runtime.exec(cmd);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return  cmd;
    }
 
   private String playRunTime(String cmd) throws Exception
   {
       //  String cmd = "adb version";
         String ret = null;
         Process p = Runtime.getRuntime().exec(cmd);
         InputStream is = p.getInputStream();
         BufferedReader reader = new BufferedReader(new InputStreamReader(is));
         String line; while ((line = reader.readLine()) != null)
         {
           //tv_result.append(line + "");
             ret = line;
         }
         p.waitFor();
         is.close();
         reader.close();
         p.destroy();
         return ret;
   }
 
}

四、有价值的参考文章

[RK3288][Android6.0] 调试笔记 --- 修改默认system/bin/下可执行程序权限_KrisFei的博客-CSDN博客_android system/bin 权限