How to process in the background without output to the screen

serkan_tr

I want to write a program. The purpose of the program is to open cmd and run ROS, enter the command "c:\opt\ros\foxy\x64\setup.bat" in cmd and run the Qt project I wrote in another file. I do not want these processes to appear on the screen.
Necessary information: ROS is a framework that provides an operating system for robot software developers. For ROS to work , c:\opt\ros\foxy\x64\setup.bat must be run in a cmd and processes must be resumed in that cmd.
I also made a Qt project, but my project doesn't work when I tap .exe directly. It works when I first run ROS via cmd and then run .exe via the same cmd.
It's kind of annoying to do this all the time, so I want to write a Qt project that does these steps for me. and I don't want these settings to appear on the screen in the background
Can something like this be done or is there an easier way?

SGaist

Hi,

Sounds like you would need some kind of launcher using QProcess to start your ros environment and then your application.

Can you do the launch from a script ?

Kent-Dorfman

@serkan_tr said in How to process in the background without output to the screen:

Can something like this be done or is there an easier way?

Well, if you were in a non-windoze environment you would execute a script containing

#! /bin/bash
(
. $PATH_TO_SETUP/setup.sh
$PATH_TO_EXE/qtprogram  2>&1 > /dev/null
)

serkan_tr

@Kent-Dorfman
Thank you

JonB

@serkan_tr
From Windows you can do the equivalent of @Kent-Dorfman's Linux shell script in a .bat file which you run from QProcess.

However there is a "wrinkle". @Kent-Dorfman's code allows for setup.sh setting environment variables for the following qtprogram call because in . $PATH_TO_SETUP/setup.sh that . at the start causes the setup.sh to be run in the same shell instance as the qtprogram which follows it.

If you Windows .bat file just goes:

c:\opt\ros\foxy\x64\setup.bat
qtprogram

then any environment variables set in setup.bat will not be inherited to qtprogram. And from

For ROS to work , c:\opt\ros\foxy\x64\setup.bat must be run in a cmd and processes must be resumed in that cmd.

I am guessing it may well set such variables.

I believe call is the vital word to achieve what you need from a .bat file. It must be used when that executes any other .bat file which sets environment variables [actually I think this is necessary any time you want to call one .bat file from another and expect it to return into the first .bat file to continue]:

call c:\opt\ros\foxy\x64\setup.bat
qtprogram

If this is put in some setupandrun.bat file you execute that via QProcess::start() (or startDetached()) I am not sure for a .bat file whether you can run it directly via start("/path/to/bat"), you might have to go start("cmd", { "/c", "/path/to/bat" }).

Finally: I just did a test to see if you can avoid the need for the extra setupandrun.bat file you would have to write/distribute. I believe you can do that by:

process->start("cmd", { "/c", R"(c:\opt\ros\foxy\x64\setup.bat & \path\to\qtprogram)" });