Weird behavior of QProcess and multiple qoutes

Manta Ray

Ahaaaa, Thanks you guys a lot!!!!!!
I really appreciate you!!!!

Guanhong

@Manta-Ray
I met the same issue and it failed.
Could you show me your codes or tell me what's wrong with my codes following, thanks

            QString strSSID = "12345678"
            QString program = "wpa_cli";
            QStringList arguments;      
            arguments << "-i" << "wlan0" << "set_network" << "0"<< "ssid" << "'\"" << strSSID << "\"'";  
            QProcess prcsWlan4;
            prcsWlan4.start(program, arguments);
            prcsWlan4.waitForFinished(-1);  
            QString strResult4 = prcsWlan4.readAllStandardOutput();

the result strResult4 is FAIL

Christian Ehrlicher

@Guanhong said in Weird behavior of QProcess and multiple qoutes:

<< "'"" << strSSID << ""'";

Why do you quote this? It's not needed at all - every value in the QStringList is passed as one parameter to your app. That's the reason why you should not use the other call - to avoid useless and wrong quotes.

Guanhong

@Christian-Ehrlicher
thank you for your swift reply

actually in my project, strSSID is a variable, it is delivered by other parameters, here I just made it a constant for convenience.

I changed
arguments << "-i" << "wlan0" << "set_network" << "0"<< "ssid" << "'"" << strSSID << ""'";
to
arguments << "-i" << "wlan0" << "set_network" << "0"<< "ssid" << "'"" + strSSID + ""'";

it still FAILed.
could you help me?

jsulm

@Guanhong Please read once more what @Christian-Ehrlicher wrote. Your change is NOT what he wrote...

Guanhong

@jsulm thank you.
I think quotes are necessary, because there is a single quote outside a double quote.
I need to process the following command by QProcess, could you show me how?
pa_cli -i wlan0 set_network 1 ssid '"hima24g"'

Christian Ehrlicher

Again: there is no need to quote an argument when using QProcess::start() with QStringList - they are only needed on the command line so bash/cmd.exe/whatever knows what a single argument is! Your ssid is hima24g and not "hima24g" or 'hima24g' ... or?

Guanhong

@Christian-Ehrlicher
Even if there are single quotes and double quotes in the command, is there no need to add quotes? I looked at earlier replies, it seems that quotes are need.

I just removed quotes and changed my codes to
arguments << "-i" << "wlan0" << "set_network" << "0"<< "ssid" << strSSID ;
FAILed too.

jsulm

@Guanhong Then add proper error handling and also read from std error of your process to see whether it prints any errors.

Guanhong

@jsulm
QString strResult4 = prcsWlan4.readAllStandardOutput();
strResult4 is FAIL

jsulm

@Guanhong said in Weird behavior of QProcess and multiple qoutes:

readAllStandardOutput()

I was talking about std ERROR (https://doc.qt.io/qt-5/qprocess.html#readAllStandardError)...

Christian Ehrlicher

Please run it on the command line. Maybe you don't have the proper privileges.

Guanhong

@Christian-Ehrlicher
I have run it on the command line, it is no problem.

Christian Ehrlicher

@Guanhong Please show how you run it on the command line

Guanhong

@Guanhong said in Weird behavior of QProcess and multiple qoutes:

<

wpa_cli -i wlan0 set_network 1 ssid '"hima24g"'
I run it on an Ubuntu console, and it can run successfully

jsulm

@Guanhong said in Weird behavior of QProcess and multiple qoutes:

wpa_cli -i wlan0 set_network 1 ssid '"hima24g"'

wpa_cli -i wlan0 set_network 1 ssid hima24g

should work just as good

Christian Ehrlicher

set_network 1

is not

"set_network" << "0"

Guanhong

wpa_cli -i wlan0 set_network 1 ssid hima24g
without quotes, it does not work on my console.

set_network 1 or set_network 0 does not matter.
It depends.

jsulm

@Guanhong So, did you try to print out https://doc.qt.io/qt-5/qprocess.html#readAllStandardError ?

Christian Ehrlicher

Looks like wpa_cli really needs additional double quotes... strange and weird program (see google for a lot of confusion due to this behavior).
So it must be

arguments << "-i" << "wlan0" << "set_network" << "0"<< "ssid" << "\"" + strSSID + "\"";