在Qt中启动并写入终端

问题描述

我正在使用Qt在Linux中进行编码.我了解使用popen或QProcess可以从程序启动终端，但是如何写入呢?我在周围的人周围google都在建议fork()和pipe().我的目的是使用终端执行ICMP ping，并在ping成功后停止.我用popen做到了，但是我无法停止ping进程，因此我的程序无法运行.

I am coding in linux using Qt. I understand that with popen or QProcess I can launch terminal from my program, but how do I write into to it? I google around people are suggesting fork() and pipe().My purpose is to do an ICMP ping with the terminal, and stop when ping successfully. I made it with popen, but I couldn't stop the ping process thus my program won't run.

推荐答案

您没有向终端写任何东西，因为没有终端.您传递要运行的程序的名称及其参数作为 QProcess::start 方法.如果您只需要知道ping是否成功，就足以检查您先前使用QProcess::start启动的进程的退出代码；您不必读取其输出.

You don't write anything to terminal because there's no terminal. You pass name of a program to run and its arguments as arguments of the QProcess::start method. If you only need to know if ping was successful or not it's enough to check the exit code of the process which you started earlier using QProcess::start; you don't have to read its output.

来自 ping(8)-Linux手册页

默认情况下，Linux下的ping会运行，直到将其停止为止.但是，您可以使用-c X选项仅发送X个数据包，并使用-w X选项将整个过程的超时设置为X秒.这样，您可以限制ping的运行时间.
以下是使用QProcess在Windows上运行ping程序的工作示例.对于Linux，您必须相应地更改ping选项(例如，将-n更改为-c).在此示例中，ping最多运行X次，其中X是您赋予Ping类构造函数的选项.一旦这些执行中的任何一个以退出代码0返回(表示成功)，就会发出值为true的result信号.如果没有成功执行，则发出result信号，其值为false.

By default ping under Linux runs until you stop it. You can however use -c X option to send only X packets and -w X option to set timeout of the whole process to X seconds. This way you can limit the time ping will take to run.
Below is a working example of using QProcess to run ping program on Windows. For Linux you have to change ping options accordingly (for example -n to -c). In the example, ping is run up to X times, where X is the option you give to Ping class constructor. As soon as any of these executions returns with exit code 0 (meaning success) the result signal is emitted with value true. If no execution is successful the result signal is emitted with value false.

#include <QCoreApplication>
#include <QObject>
#include <QProcess>
#include <QTimer>
#include <QDebug>


class Ping : public QObject {

    Q_OBJECT

public:

    Ping(int count)
    : QObject(), count_(count) {

        arguments_ << "-n" << "1" << "example.com";

        QObject::connect(&process_,
                         SIGNAL(finished(int, QProcess::ExitStatus)),
                         this,
                         SLOT(handlePingOutput(int, QProcess::ExitStatus)));
    };

public slots:

    void handlePingOutput(int exitCode, QProcess::ExitStatus exitStatus) {
        qDebug() << exitCode;
        qDebug() << exitStatus;
        qDebug() << static_cast<QIODevice*>(QObject::sender())->readAll();
        if (!exitCode) {
            emit result(true);
        } else {
            if (--count_) {
                QTimer::singleShot(1000, this, SLOT(ping()));
            } else {
                emit result(false);
            }
        }
    }

    void ping() {
        process_.start("ping", arguments_);
    }

signals:

    void result(bool res);

private:

    QProcess process_;
    QStringList arguments_;
    int count_;
};


class Test : public QObject {

    Q_OBJECT

public:
    Test() : QObject() {};

public slots:
    void handle(bool result) {
        if (result)
            qDebug() << "Ping suceeded";
        else
            qDebug() << "Ping failed";
    }
};


int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);

    Test test;
    Ping ping(3);
    QObject::connect(&ping,
                     SIGNAL(result(bool)),
                     &test,
                     SLOT(handle(bool)));

    ping.ping();
    app.exec();
}

#include "main.moc"

这篇关于在Qt中启动并写入终端的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！