How to execute a detached C++ executable file from another Qt program?

Question

I want to execute an .exe file, which was compiled by g++ (or gcc) from a Qt program. I refer to this topic and try to make it run:

// Setup the working directory
QDir::setCurrent("/home/myproject");

// Start the process (uses new working dir)
bool t= myProc.startDetached("./work");
if (t==false) std::cout<< "Error";
else std::cout <<"OK";

but the result I have is always "Error" and there is no change in my screen even if the program "work" is a GUI program. I did it in terminal but in QProcess I can't :(. What am I doing wrong?

You have inverted logic there: t is false when there’s an error, not true. Try with an absolute path instead of ./work. The current directory looks broken, it should be an absolute path also, e.g. /home/youruser. Also note that startDetached is a static method and does nothing to myProc, QProcess::startDetached(…) would be the usual syntax (but yours should work, too) — Frank Osterfeld
– Frank Osterfeld, Commented Apr 19, 2016 at 11:23
@FrankOsterfeld sorry, my mistake. I fixed that. The program worked in terminal but in QProcess it can't run :( — Nguyễn Chí
– Nguyễn Chí, Commented Apr 19, 2016 at 13:06

John · Accepted Answer · 2016-04-19 13:43:42Z

1

It's likely a typo issue. Make sure QDir::setCurrent("home/") does return true; if not, directory change failed and you are not in the directory you expect.

Try starting your executbale attached first (use myProc.execute() instead of myProc.startDetached(), and check what happens. This may reveal some errors that you cannot see when started detached. Make sure your program 'work' does not perform any input from stdin.

edited Apr 19, 2016 at 13:43

answered Apr 19, 2016 at 9:45

John

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3 Comments

Nguyễn Chí Over a year ago

it's not my problem. I think it's about QProcess :(

John Over a year ago

@Nguyễn Chí: please, give some more inputs... difficult to understand what's happening with the fex info you provided.

Nguyễn Chí Over a year ago

it's a GUI program, is a sample code of OpenCV library in C++.

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