c++ - 在 Qt 控制台应用程序中读写 QProcess

Question

注意:这似乎是一个特定的问题，但希望它可以针对所有相关问题进行编辑

我需要与 QProcess 对象交互。

问题:

我没有从 QProcess 得到任何输出打电话后 QProcess:write(input)

更多信息:

遍历 doc pages引导我在下面创建一个示例:

我有一个脚本请求用户输入，并最终根据用户输入显示适当的消息。

测试:

在我的测试脚本中添加“日志”功能后，发生了以下情况:

• 脚本执行
• 脚本请求用户输入(由“第一个”qDebug() << p->readAll() 确认)
• 脚本接受来自 QProcess 的输入(由脚本“日志输出”确认)

在此之后，没有收到任何输出。以下 2 个调试语句都触发(即每个等待 30 秒)

if (!p->waitForReadyRead()) {
    qDebug() << "waitForReadyRead() [false] : CODE: " << QVariant(p->error()).toString() << " | ERROR STRING: " << p->errorString();
}
if (!p->waitForFinished()) {
    qDebug() << "waitForFinished() [false] : CODE: " << QVariant(p->error()).toString() << " | ERROR STRING: " << p->errorString();
}

其次是:

QString s = QString(p->readAll() + p->readAllStandardOutput());

哪里s是一个空字符串。

问题是 s 应该包含“成功”或“失败”

调用代码:

QString cmd = QString("sh -c \"/path/to/bashscript.sh\"");
QString input = QString("Name");
QString result = runCommand(cmd, input)

处理代码:

//takes 2 parameters, 
//    cmd which is the code to be executed by the shell
//    input which acts as the user input

QString runCommand(QString cmd, QString input){
    QProcess *p = new QProcess(new QObject());
    p->setProcessChannelMode(QProcess::MergedChannels);   //no actual reason to do this
    p->start(cmd);
    if (p->waitForStarted()) {
        if (!p->waitForReadyRead()) {
            qDebug() << "waitForReadyRead() [false] : CODE: " << QVariant(p->error()).toString() << " | ERROR STRING: " << p->errorString();
        }
        if (!p->waitForFinished()) {

            //reads current stdout, this will show the input request from the bash script
            //e.g. please enter your name:
            qDebug() << p->readAll();  

            //here I write the input (the name) to the process, which is received by the script
            p->write(ps.toLatin1());

            //the script should then display a message i.e. ("success" o "failed")
            if (!p->waitForReadyRead()) {
                qDebug() << "waitForReadyRead() [false] : CODE: " << QVariant(p->error()).toString() << " | ERROR STRING: " << p->errorString();
            }
            if (!p->waitForFinished()) {
                qDebug() << "waitForFinished() [false] : CODE: " << QVariant(p->error()).toString() << " | ERROR STRING: " << p->errorString();
            }
        }
        QString s = QString(p->readAll() + p->readAllStandardOutput());
        return s;
    }
    else{
        qDebug() << "waitForStarted() [false] : CODE: " << QVariant(p->error()).toString() << " | ERROR STRING: " << p->errorString();
    }
    p->waitForFinished();
    p->kill();
    return QString();
}

script.sh ( -rwxrwxr-x )

#!/bin/bash
#returns 
#    "success" on non empty $n value
#    "failed: on empty $n value
#
echo "enter your name:"
read n
if [[ ! -z $n ]];
then
        echo "success"
        exit 0;
else
        echo "failed"
        exit 1;
fi

更新

@KevinKrammer 我按照你说的修改了运行命令，还使用带有 args 的 QStringList。

仍然没有得到输出，实际上是 waitForReadyRead()和 waitForFinished() returns false立即。

调用方式:

QString r = runCommand(QString("text"));

处理代码:

QString runCommand(QString input){      

    QProcess *p = new QProcess(new QObject());    
    p->setProcessChannelMode(QProcess::MergedChannels);

    //script is the same script refered to earlier, and the `cd /home/dev` IS required
    p->start("sh", QStringList() << "-c" << "cd /home/dev" << "./script");
    ;
    if (p->waitForStarted()) {
        if (!p->waitForReadyRead(5000)) {
            qDebug() << "waitForReadyRead() [false] : CODE: " << QVariant(p->error()).toString() << " | ERROR STRING: " << p->errorString();
        }
        qDebug() << p->readAll();
        p->write(input.toLatin1());
        if(!p->waitForFinished(5000)){
            qDebug() << "waitForFinished() [false] : CODE: " << QVariant(p->error()).toString() << " | ERROR STRING: " << p->errorString();
        }
        QString s = QString(p->readAll() + p->readAllStandardOutput());
        return s;
    }
    else{
        qDebug() << "waitForStarted() [false] : CODE: " << QVariant(p->error()).toString() << " | ERROR STRING: " << p->errorString();
    }
    p->waitForFinished();
    p->kill();
    return QString();
}

进程的终端输出:

started
readChannelFinished
exit code =  "0"
waitForReadyRead() [false] : CODE:  "5"  | ERROR STRING:  "Unknown error"
""
waitForFinished() [false] : CODE:  "5"  | ERROR STRING:  "Unknown error"
Press <RETURN> to close this window...

对此有何想法？

更新 2

@Tarod 感谢您花时间提出解决方案。

它有效，但并不完全符合预期。

我完全复制了你的代码。

在 mReadyReadStandardOutput() 中做了一些改动

请参阅下面的其他信息。

问题:

运行应用程序(和脚本)后，我得到一个结果 -> 好极了

每次都是错误的结果，即“失败”。 -> 不太好

终端输出:

void MyProcess::myReadyRead()
void MyProcess::myReadyReadStandardOutput()
"enter your name:\n"
""
void MyProcess::myReadyRead()
void MyProcess::myReadyReadStandardOutput()
"failed\n"
Press <RETURN> to close this window...

脚本内容:

#!/bin/bash
echo "enter your name:"
read n
echo $n > "/tmp/log_test.txt"
if [[ ! -z "$n" ]];
then
        echo "success"
        exit 0;
else
        echo "failed"
        exit 1;
fi

/tmp/log_test.txt输出

myname

从控制台手动运行:

dev@dev-W55xEU:~$ ls -la script 
-rwxrwxr-x 1 dev dev 155 Jan 25 14:53 script*

dev@dev-W55xEU:~$ ./script 
enter your name:
TEST_NAME
success

dev@dev-W55xEU:~$ cat /tmp/log_test.txt 
TEST_NAME

完整代码:

#include <QCoreApplication>
#include <QProcess>
#include <QDebug>

class MyProcess : public QProcess
{
    Q_OBJECT

public:
    MyProcess(QObject *parent = 0);
    ~MyProcess() {}

public slots:
    void myReadyRead();
    void myReadyReadStandardOutput();
};

MyProcess::MyProcess(QObject *parent)
{
    connect(this,SIGNAL(readyRead()),
            this,SLOT(myReadyRead()));
    connect(this,SIGNAL(readyReadStandardOutput()),
            this,SLOT(myReadyReadStandardOutput()));
}

void MyProcess::myReadyRead() {
    qDebug() << Q_FUNC_INFO;
}

void MyProcess::myReadyReadStandardOutput() {
    qDebug() << Q_FUNC_INFO;
    // Note we need to add \n (it's like pressing enter key)
    QString s = this->readAllStandardOutput();
    qDebug() << s;
    if (s.contains("enter your name")) {
        this->write(QString("myname" + QString("\n")).toLatin1());
        qDebug() << this->readAllStandardOutput();
    }
}

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

    MyProcess *myProcess = new MyProcess();

    QString program = "/home/dev/script";

    myProcess->start("/bin/sh", QStringList() << program);

    a.exec();
}

#include "main.moc"

脚本问题？ Q流程问题？

Answer 1

不幸的是我没有你所有的代码，所以我做了一个例子。希望对您有所帮助。

如果我将我的代码与您的代码进行比较，我认为问题可能是您在编写后没有调用 readAllStandardOutput() 或者您可能没有在调用 exec()你的 main.cpp。

#include <QCoreApplication>
#include <QProcess>
#include <QDebug>

class MyProcess : public QProcess
{
    Q_OBJECT

public:
    MyProcess(QObject *parent = 0);
    ~MyProcess() {}

public slots:
    void myReadyRead();
    void myReadyReadStandardOutput();
};

MyProcess::MyProcess(QObject *parent)
{
    connect(this,SIGNAL(readyRead()),
            this,SLOT(myReadyRead()));
    connect(this,SIGNAL(readyReadStandardOutput()),
            this,SLOT(myReadyReadStandardOutput()));
}

void MyProcess::myReadyRead() {
    qDebug() << Q_FUNC_INFO;
}

void MyProcess::myReadyReadStandardOutput() {
    qDebug() << Q_FUNC_INFO;
    // Note we need to add \n (it's like pressing enter key)
    this->write(QString("myname" + QString("\n")).toLatin1());
    // Next line no required
    // qDebug() << this->readAll();
    qDebug() << this->readAllStandardOutput();

}

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

    MyProcess *myProcess = new MyProcess();

    QString program = "/home/fran/code/myscript.sh";

    myProcess->start("/bin/sh", QStringList() << program);

    a.exec();
}

#include "main.moc"

测试应用程序的脚本:

echo "enter your name:"
read n
if [ ! -z "$n" ];
then
    echo "success"
    exit 0;
else
    echo "failed"
    exit 1;
fi