View Full Version : QProcess error Using Arguments Qt 4.5

13th April 2009, 05:17
Hi All,

My Problem is Using QProcess Class, I have a CLI application that works without arguments but if I pass some Arguments the process not run. Maybe I'm doing something wrong :confused:. This is a Code sample.

QObject *parent;
QProcess *nAp = new QProcess(parent);

//Path to the Application
QString appPath = "/home/username/ConsoleApp ";
QStringList arguments;
arguments << "one";
arguments << "two";

nAp->start( appPath, arguments );
if(!nAp->waitForStarted(-1)) {
qDebug() << "Ap has not started";

Thanks for the Help.

14th April 2009, 19:30
I fix the problem myself the error was the space at the end of the Application Path.

13th May 2009, 22:23
I have a similar problem, but it's not caused by a trailing space.

This works:

proc = new QProcess( parent );
proc->start( "/home/user/path/to/prog/myprogram.exe -a -b -c" );

This doesn't work:

proc = new QProcess( parent );
proc->setWorkingDirectory( "/home/user/path/to/prog" );
proc->start( "myprogram.exe -a -b -c" );

Adding a trailing '/' to the path in setWorkingDirectory makes no difference.

The weirdest thing is, if I change "myprogram.exe" to "ls", for instance, then "ls" works and returns the contents of /home/user/path/to/prog

What am I missing ?

15th May 2009, 13:19
Very strange - I have the opposite: I cannot call command line tools, but only graphical programs (other thread).

Does startDetached help? What about
proc->start("myprogram", QStringList() << "-a -b")?

15th May 2009, 15:36
Console vs Gui should make no difference (or, maybe you're creating the QProcess from inside a Widget ?) I call start() directly from main, then pass the QProcess handle to my MainWindow so that my widgets can reference it.

In my case, I don't want to detach, since I need continuous communication between the QProcess and my app.

The argument list is not a problem in my case. All of these work equally:

proc->start("/path/to/myprogram.exe", QStringList() << "-a" << "-b")
proc->start("/path/to/myprogram.exe", QStringList() << "-a -b")
proc->start("/path/to/myprogram.exe -a -b")

15th May 2009, 16:26
Console vs Gui - yes, in theory. On Mac, I cannot open a console at all. But anyway...

So the only thing left: setWorkingDirectory hast nothing to do where QProcess searches your program. That would explain why ls is started - it is in your path. Your program to start is not.

proc = new QProcess( parent );
proc->setWorkingDirectory( "/home/user/path/to/prog" );
proc->start( "/home/user/path/to/prog/myprogram.exe -a -b -c" );
should do the job

15th May 2009, 16:56
Well that makes sense :) I had thought setWorkingDirectory() would actually do a "cd" to this path before launching the process, which is not exactly the same thing...

Thanks for the heads-up.