Java-循环运行流程

Question

我想使用ProcessBuilder在循环中运行Process ：

    system.out.println(m_sizeOfEnv); // 2
    Process process;
    for(int i =0 ; i < m_sizeOfEnv; i++){
       ProcessBuilder pb = new ProcessBuilder(pathTo); //path to .sh file
       process = pb.start();

       BufferReader br = new BufferReader(new InputStreamReadser (process.getInputStream())); // print only once
       String line = null;
       while((line = br.readLine())!=null ){
          system.out.println(line); // prints the process output
       }

       process.destroy();
    }

该循环运行m_sizeOfEnv次，但该过程仅运行一次。 为什么？