qt中创建进程

process.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include<QProcess>
namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private slots:
    void on_pushButton_clicked();
    void get_msg();
    void start_signal1();

    void on_pushButton_2_clicked();

private:
    Ui::MainWindow *ui;
    QProcess *p;
};

#endif // MAINWINDOW_H

process.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<QDebug>
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    p = new QProcess();
connect(p,SIGNAL(readyReadStandardOutput()),this,SLOT(get_msg()));
connect(p,SIGNAL(started()),this,SLOT(start_signal1()));
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButton_clicked()
{
p->start("ls");
}
void MainWindow::get_msg()
{
while(p->canReadLine())
{
    QString tmp = p->readLine();
    ui->listWidget->addItem(tmp);
}

}
void MainWindow::start_signal1()
{
    qDebug()<<"start";


}

void MainWindow::on_pushButton_2_clicked()
{
      delete ui->listWidget->currentItem();
  //  ui->listWidget->removeItemWidget(ui->listWidget->currentItem());

    qDebug()<<"remove";
    //ui->listWidget->clear();
}