I need to run an external exe through Qt application which requires commands to be entered in windows command prompt.
QString exePath = "C:\Windows\system32\cmd.exe";
QProcess pro;
pro.start(exePath);
pro.execute("cmd.exe");
But I got output like below plain cmd prompt
But I want windows command prompt like expected cmd
You need to read from QProcess standart output and print it on screen.
You can use pro.waitForReadyRead() and if it returns true do
QByteArray arr = pro.readAllStandardOutput();
QString str(arr);
qDebug() << str;
Better decision is to use signal slot mechanism and implement onReadyToRead() slot and connect QProcess readyReadStandardOutput() signal to it.
pro.start(exePath);
pro.execute("cmd.exe");
You should not use this two methods at same time, QProcess::execute is static member.
You need to start process detached:
QString exePath = "C:\Windows\system32\cmd.exe";
QProcess pro;
pro.startDetached(exePath);
pro.waitForStarted();
//Event Loop here
Related
I'm new using QT, I need to execute a CMD command on windows and get the output of this command as a string to later process and get specific data. The following code works well (it seems to work well). The only problem is that I get the following warning: "start is deprecated", I think this warning message is because the start method needs an arguments list as parameter.
QString command = "tasklist /FI \"IMAGENAME eq notepad.exe\"";
QProcess *executeCommand = new QProcess();
executeCommand->start(command);
executeCommand->waitForFinished(-1);
QString output = executeCommand->readAllStandardOutput();
executeCommand->terminate();
qDebug() << commandOutput;
how can I remove this warning message?
Also I found in the web that I can use system() to execute a CMD command, but I'm not able to catch the output as string.
Another question: which of the above options is better to achieve what I'm trying to do, the QProcess or System (if is possible to get the output as QString)?
Thanks in advance!
There is an answer read QProcess output to string recommending static method QProcess::readAllStandardOutput() returning QByteArray. Then just instantiate QString from QByteArray implicitly.
If you are working on Qt application, it is better to stay inside Qt API to keep the code more or less portable.
I want to write a routine that will automatically change my Machine learning parameters and execute the (Machine learning) code multiple times and save its result into a text file.
The Machine learning code is run from the Ubuntu terminal and its result also are written to the Ubuntu terminal.
I need a way to read data and write data to the Ubuntu terminal from the C++ code.
What I have found so far is the QProcess:
QProcess process;
process.start("gnome-terminal"); //THE TERMINAL IS OPENED INDEED
char w[] = "write";
process.write(w,sizeof(w));
process.waitForFinished();
But nothing is written or read from it
What does working is:
QProcess process1;
QProcess process2;
process1.setStandardOutputProcess(&process2);
process1.start("echo 0534230313");
process2.start("sudo -S poweroff");
process2.setProcessChannelMode(QProcess::ForwardedChannels);
And also this works:
int result = system("echo 0534230313 | sudo -S poweroff"); ///COMMANDS TO TERMINAL
int result2 = system("gnome-terminal"); ///OPEN TERMINAL
But the problem is that I wont be able to read the output result (My Machine learning program can open and write to the terminal by itself)
Use the finished signal to read the process output results
connect( poProcess, static_cast<void (QProcess::*)(int,QProcess::ExitStatus)>(&QProcess::finished),
[=](int,QProcess::ExitStatus)
{
QByteArray oProcessOutput=
poProcess->readAllStandardOutput();
// Parse the process output.
//
// Mark process for deletion.
emit poProcess->deleteLater();
});
In my QT widget application I am attempting to run a shellscript that opens a C++ program and provides inputs to the program as well. The program starts a command prompt that requires the users input to start. Once the program is started the output of the program is redirected via the standard output to a text file. I am attempting to use QProcess to open and run this shellscript, then read the standard output that is being used to print the result of the C++ program to the text file. The shell script only runs this process and does not terminate it. This is because I need to continuously read this output into the GUI as the program is running. It will not be sufficient to wait until the program is finished to read this information. I am fairly new to QT and C++ programming. I was hoping that someone could help me with my implementation of this.
QProcess process;
process.start("/home/pi/Desktop/ShellScripts/RunTutorial3.sh");
QString output =process.readAllStandardOutput();
qDebug() << output;
QString err = process.readAllStandardError();
qDebug() << err;
I have experimented with using other read function such as readline and also trying to start the process as a detatched process. I have not had success with any of my experimentations. Is it possible to do what I am attempting in QT. I just need the program to run continuously and for QT to read this output every so often.
Shell script:
#!/bin/bash
cd
cd Desktop
cd tutorial3App
cd bin
echo "start" | ./tutorial3
C++ code: I need the meanTOE value to be captured in standard output to use in my GUI.
/ Calculate average time to end of discharge
double meanToE = std::accumulate(ToESamples.begin(), ToESamples.end(), 0.0)/ToESamples.size();
file << ": EOL in " << meanToE << " s" << std::endl;
As I said in my comments one of the main problems is that when you run tutorial3 that process is separated so you can not get the output. Therefore, I recommend executing it directly, and QProcess is probably a local variable, eliminating after printing an empty text, a possible solution is to create a pointer. Another improvement would be to use the readyReadStandardOutput and readyReadStandardError signals since the impressions are not automatic.
QProcess *process = new QProcess(this);
connect(process, &QProcess::readyReadStandardOutput, [process, this](){
QString output =process->readAllStandardOutput();
qDebug() << "output: "<< output;
});
connect(process, &QProcess::readyReadStandardError, [process](){
QString err = process->readAllStandardError();
qDebug() << "error: "<<err;
});
process->setWorkingDirectory("/home/pi/Desktop/tutorial3App/bin/")
process->start("tutorial3", QStringList() << "start");
I think you have to read about signals and slots in Qt. QProcess has got a signal readyReadStandardOutput. So you have to connect to this signal and in your slot you should use QProcess function readAllStandardOutput. In other words when your shell programm outputs something you catch it in your slot and dump it or whatever you want.
Check the answer on this question. It might help you.
reading and writing to QProcess in Qt Console Application
I want to run a qprocess (the program adb) and when the process is finished return the results to the calling function. However, there's every possibility that adb could find itself in a loop, printing error messages such as "ADB server didn't ACK" to stdout, not ever finishing. I need to trap these errors.
QProcess run_command;
connect(&run_command,SIGNAL(readyReadStandardOutput()),this,SLOT( dolog() ));
QString result=RunProcess("adb connect 192.168.1.100");
...
QString MainWindow::RunProcess(QString cstring)
{
run_command.start(cstring);
// keep gui active for lengthy processes.
while(run_command.state() != QProcess::NotRunning)
qApp->processEvents();
QString command=run_command.readAll();
return command; // returns nothing if slot is enabled.
}
void MainWindow::dolog()
{
QString logstring = run_command.readAllStandardOutput();
if (logstring.contains("error condition")
logfile("Logfile:"+logstring);
}
If I enable the signal/slot, dolog() prints stdout to a logfile, but RunProcess returns a blank string. If I disable the signal/slot, RunProcess() returns the qprocess output as expected.
First you need to identify which output stream the command in question is using for its errors.
It is very like stderr so you would need to connect to the readyReadStandardError() signal instead.
For the command itself I would recommend to split it into command and arguments and use the QProcess::start() overload that takes the command and a list of arguments.
Just more robust than to rely on a single string being correctly separated again.
I use QProcess to run another program. The command is airodump-ng mon0.
Its output is changing anytime, and is whole different (also not like ping command, changed by line). I want use QProcess to run that program and get its output while it is still running.
Here is the code:
pushButton_clicked()
{
myprocess = new QProcess(this);
connect(myprocess,SIGNAL(readReadStandardOutput()),this,SLOT(outlog()));
myprocess->start("sudo -A ./airodump-ng mon0");
}
outlog()
{
QString abc = myprocess->readAllStandardOutput();
textEdit->setText(abc);
}
In the program airodump-ng, I've already added code setvbuf(stdout,(char*)NULL,_IONBF,0); to use row buffering.