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How to use curl cmd in c++/qt

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  • R Rua3n

    @jeremy_k said in How to use curl cmd in c++/qt:

    QString, eg { "/c", "curl", "-H", ...}.

    I already tried this, also doesn't work, does it work on your side?

    Christian EhrlicherC Offline
    Christian EhrlicherC Offline
    Christian Ehrlicher
    Lifetime Qt Champion
    wrote on last edited by
    #4

    Why is cmd.exe needed anyway?

    Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
    Visit the Qt Academy at https://academy.qt.io/catalog

    1 Reply Last reply
    2
    • R Rua3n

      @jeremy_k said in How to use curl cmd in c++/qt:

      QString, eg { "/c", "curl", "-H", ...}.

      I already tried this, also doesn't work, does it work on your side?

      jeremy_kJ Offline
      jeremy_kJ Offline
      jeremy_k
      wrote on last edited by
      #5

      @Rua3n said in How to use curl cmd in c++/qt:

      @jeremy_k said in How to use curl cmd in c++/qt:

      QString, eg { "/c", "curl", "-H", ...}.

      I already tried this, also doesn't work, does it work on your side?

      Natural language is ambiguous. Post the code.

      Asking a question about code? http://eel.is/iso-c++/testcase/

      1 Reply Last reply
      2
      • jeremy_kJ jeremy_k

        Regarding the use of curl + cmd.exe + QProcess: Qt has a built-in http client, QNetworkAccessManager.

        @Rua3n said in How to use curl cmd in c++/qt:

        Why I'm getting in the output returned by process the following errors:

        QString Debugger::process(const QString& program, const QStringList& arguments)
        {
            QProcess process;
            [...]
            process.start(program, arguments);
            [...]
        }
        QString output = process("cmd.exe", {"/c curl -H \"Accept: application/vnd.github.v3.raw\" -L \"https://github.com/jajabu33/test/branches\""});
        

        The QStringList passed to QProcess::start should have one argument per QString, eg { "/c", "curl", "-H", ...}. Use QProcess::splitCommand() if multiple arguments must be expressed as a space delimited string.

        QEventLoop eventLoop;
        QObject::connect(&process, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished), &eventLoop, [&] { eventLoop.quit(); });
        eventLoop.exec();
        

        This is a lot of code to accomplish the same thing as QProcess::waitForFinished(), if the goal is to avoid the main QCoreApplication event loop. If that isn't the goal, introducing nested event loops has a tendency to create subtle problems. Set up a connection to read output, return, and let the main event loop do its thing.

        JonBJ Online
        JonBJ Online
        JonB
        wrote on last edited by JonB
        #6

        @jeremy_k said in How to use curl cmd in c++/qt:

        The QStringList passed to QProcess::start should have one argument per QString, eg { "/c", "curl", "-H", ...}.

        Just for the record. This works for Windows cmd /c but would not under Linux for sh -c. If the OP finds it easier the following, which would be required under Linux, also works under Windows and saves splitting:

        process("cmd.exe", {"/c",  "curl -H \"Accept: application/vnd.github.v3.raw\" -L \"https://github.com/jajabu33/test/branches\""});
        

        I am with @Christian-Ehrlicher. There are e.g. no shell redirection symbols here. Why bother with cmd /c?

        process("curl", {"-H", "Accept: application/vnd.github.v3.raw", "-L", "https://github.com/jajabu33/test/branches"});
        

        Whether OP really needs curl and a separate OS command when Qt has a built-in http client, QNetworkAccessManager, is another matter.

        R jeremy_kJ 2 Replies Last reply
        2
        • JonBJ JonB

          @jeremy_k said in How to use curl cmd in c++/qt:

          The QStringList passed to QProcess::start should have one argument per QString, eg { "/c", "curl", "-H", ...}.

          Just for the record. This works for Windows cmd /c but would not under Linux for sh -c. If the OP finds it easier the following, which would be required under Linux, also works under Windows and saves splitting:

          process("cmd.exe", {"/c",  "curl -H \"Accept: application/vnd.github.v3.raw\" -L \"https://github.com/jajabu33/test/branches\""});
          

          I am with @Christian-Ehrlicher. There are e.g. no shell redirection symbols here. Why bother with cmd /c?

          process("curl", {"-H", "Accept: application/vnd.github.v3.raw", "-L", "https://github.com/jajabu33/test/branches"});
          

          Whether OP really needs curl and a separate OS command when Qt has a built-in http client, QNetworkAccessManager, is another matter.

          R Offline
          R Offline
          Rua3n
          wrote on last edited by Rua3n
          #7

          @JonB said in How to use curl cmd in c++/qt:

          process("cmd.exe", {"/c", "curl -H "Accept: application/vnd.github.v3.raw" -L "https://github.com/jajabu33/test/branches""});

          This doesnt work on Windows at my side. Im trying to learn how to properly get the cmd output.

          JonBJ 1 Reply Last reply
          0
          • R Rua3n

            @JonB said in How to use curl cmd in c++/qt:

            process("cmd.exe", {"/c", "curl -H "Accept: application/vnd.github.v3.raw" -L "https://github.com/jajabu33/test/branches""});

            This doesnt work on Windows at my side. Im trying to learn how to properly get the cmd output.

            JonBJ Online
            JonBJ Online
            JonB
            wrote on last edited by JonB
            #8

            @Rua3n
            I don't know what "doesn't work" means. Same error as originally? You can guess from the mention of application that it may not be receiving your command line as intended.

            Your code for getting the output is correct. You don't check the exit status, which is worth doing, but it can get messed up using cmd /c.

            I suggested an alternative, did you at least try it?

            For now would curl accept .Accept:application/vnd.github.v3.raw without a space? Then each arguments could be passed without quotes, might simplify.

            R 1 Reply Last reply
            0
            • JonBJ JonB

              @Rua3n
              I don't know what "doesn't work" means. Same error as originally? You can guess from the mention of application that it may not be receiving your command line as intended.

              Your code for getting the output is correct. You don't check the exit status, which is worth doing, but it can get messed up using cmd /c.

              I suggested an alternative, did you at least try it?

              For now would curl accept .Accept:application/vnd.github.v3.raw without a space? Then each arguments could be passed without quotes, might simplify.

              R Offline
              R Offline
              Rua3n
              wrote on last edited by Rua3n
              #9

              @JonB
              Does this answer what "doesn't work" means?

              QString output = process("curl", {"-H", "Accept: application/vnd.github.v3.raw", "-L", "https://github.com/jajabu33/test/branches"});
              

              8cd0abcf-9c27-40eb-87dc-8c992658329f-image.png


              QString output = process("curl", {"-H ", "\"Accept: application/vnd.github.v3.raw\" ", "-L ", "\"https://github.com/jajabu33/test/branches\""});
              curl: option -L : is unknown
              curl: try 'curl --help' for more information
              

              QString output = process("curl.exe", {"-H \"Accept: application/vnd.github.v3.raw\" -L \"https://github.com/jajabu33/test/branches\""});
              
              curl: (2) no URL specified!
              curl: try 'curl --help' for more information
              

              QString output = process("curl", {"-H", "\"Accept: application/vnd.github.v3.raw\"", "-L", "\"https://github.com/jajabu33/test/branches\""});
              
              curl: (3) URL using bad/illegal format or missing URL
              

              QString output = process("cmd.exe", {"/c",  "curl -H \"Accept: application/vnd.github.v3.raw\" -L \"https://github.com/jajabu33/test/branches\""});
              

              a0514829-61cc-4b56-800c-84eef4a94e6e-image.png


              QString output = process("cmd.exe", {"/c \"curl -H \"Accept: application/vnd.github.v3.raw\" -L \"https://github.com/jajabu33/test/branches\"\""});
              
              The system cannot find the path specified.
              

              QString output = process("cmd.exe", {"/c curl -H \"Accept: application/vnd.github.v3.raw\" -L \"https://github.com/jajabu33/test/branches\""});
              
               % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                              Dload  Upload   Total   Spent    Left  Speed
              
               0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
               0     0    0     0    0     0      0      0 --:--:--  0:00:01 --:--:--     0
               0     0    0     0    0     0      0      0 --:--:--  0:00:01 --:--:--     0curl: (6) Could not resolve host: application
              curl: (3) URL using bad/illegal format or missing URL
              
              Christian EhrlicherC 1 Reply Last reply
              0
              • JonBJ JonB

                @jeremy_k said in How to use curl cmd in c++/qt:

                The QStringList passed to QProcess::start should have one argument per QString, eg { "/c", "curl", "-H", ...}.

                Just for the record. This works for Windows cmd /c but would not under Linux for sh -c. If the OP finds it easier the following, which would be required under Linux, also works under Windows and saves splitting:

                process("cmd.exe", {"/c",  "curl -H \"Accept: application/vnd.github.v3.raw\" -L \"https://github.com/jajabu33/test/branches\""});
                

                I am with @Christian-Ehrlicher. There are e.g. no shell redirection symbols here. Why bother with cmd /c?

                process("curl", {"-H", "Accept: application/vnd.github.v3.raw", "-L", "https://github.com/jajabu33/test/branches"});
                

                Whether OP really needs curl and a separate OS command when Qt has a built-in http client, QNetworkAccessManager, is another matter.

                jeremy_kJ Offline
                jeremy_kJ Offline
                jeremy_k
                wrote on last edited by
                #10

                @JonB said in How to use curl cmd in c++/qt:

                @jeremy_k said in How to use curl cmd in c++/qt:

                The QStringList passed to QProcess::start should have one argument per QString, eg { "/c", "curl", "-H", ...}.

                Just for the record. This works for Windows cmd /c but would not under Linux for sh -c.

                Tokenization as an external process is silly, but you are right.

                Asking a question about code? http://eel.is/iso-c++/testcase/

                R 1 Reply Last reply
                0
                • jeremy_kJ jeremy_k

                  @JonB said in How to use curl cmd in c++/qt:

                  @jeremy_k said in How to use curl cmd in c++/qt:

                  The QStringList passed to QProcess::start should have one argument per QString, eg { "/c", "curl", "-H", ...}.

                  Just for the record. This works for Windows cmd /c but would not under Linux for sh -c.

                  Tokenization as an external process is silly, but you are right.

                  R Offline
                  R Offline
                  Rua3n
                  wrote on last edited by
                  #11

                  @jeremy_k said in How to use curl cmd in c++/qt:

                  @JonB said in How to use curl cmd in c++/qt:

                  @jeremy_k said in How to use curl cmd in c++/qt:

                  The QStringList passed to QProcess::start should have one argument per QString, eg { "/c", "curl", "-H", ...}.

                  Just for the record. This works for Windows cmd /c but would not under Linux for sh -c.

                  Tokenization as an external process is silly, but you are right.

                  What works for Windows?

                  1 Reply Last reply
                  0
                  • R Rua3n

                    @JonB
                    Does this answer what "doesn't work" means?

                    QString output = process("curl", {"-H", "Accept: application/vnd.github.v3.raw", "-L", "https://github.com/jajabu33/test/branches"});
                    

                    8cd0abcf-9c27-40eb-87dc-8c992658329f-image.png


                    QString output = process("curl", {"-H ", "\"Accept: application/vnd.github.v3.raw\" ", "-L ", "\"https://github.com/jajabu33/test/branches\""});
                    curl: option -L : is unknown
                    curl: try 'curl --help' for more information
                    

                    QString output = process("curl.exe", {"-H \"Accept: application/vnd.github.v3.raw\" -L \"https://github.com/jajabu33/test/branches\""});
                    
                    curl: (2) no URL specified!
                    curl: try 'curl --help' for more information
                    

                    QString output = process("curl", {"-H", "\"Accept: application/vnd.github.v3.raw\"", "-L", "\"https://github.com/jajabu33/test/branches\""});
                    
                    curl: (3) URL using bad/illegal format or missing URL
                    

                    QString output = process("cmd.exe", {"/c",  "curl -H \"Accept: application/vnd.github.v3.raw\" -L \"https://github.com/jajabu33/test/branches\""});
                    

                    a0514829-61cc-4b56-800c-84eef4a94e6e-image.png


                    QString output = process("cmd.exe", {"/c \"curl -H \"Accept: application/vnd.github.v3.raw\" -L \"https://github.com/jajabu33/test/branches\"\""});
                    
                    The system cannot find the path specified.
                    

                    QString output = process("cmd.exe", {"/c curl -H \"Accept: application/vnd.github.v3.raw\" -L \"https://github.com/jajabu33/test/branches\""});
                    
                     % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                                    Dload  Upload   Total   Spent    Left  Speed
                    
                     0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
                     0     0    0     0    0     0      0      0 --:--:--  0:00:01 --:--:--     0
                     0     0    0     0    0     0      0      0 --:--:--  0:00:01 --:--:--     0curl: (6) Could not resolve host: application
                    curl: (3) URL using bad/illegal format or missing URL
                    
                    Christian EhrlicherC Offline
                    Christian EhrlicherC Offline
                    Christian Ehrlicher
                    Lifetime Qt Champion
                    wrote on last edited by Christian Ehrlicher
                    #12

                    @Rua3n said in How to use curl cmd in c++/qt:

                    QString output = process("curl", {"-H ", ""Accept: application/vnd.github.v3.raw" ", "-L ", ""https://github.com/jajabu33/test/branches""});
                    curl: option -L : is unknown

                    It's -L and not -L , and the quoting of the url is wrong since the url is https://github.com/jajabu33/test/branches and not "https://github.com/jajabu33/test/branches". Same goes for the argument for -H.
                    @JonB already told you this but you ignored him.

                    Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                    Visit the Qt Academy at https://academy.qt.io/catalog

                    R 1 Reply Last reply
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                    • Christian EhrlicherC Christian Ehrlicher

                      @Rua3n said in How to use curl cmd in c++/qt:

                      QString output = process("curl", {"-H ", ""Accept: application/vnd.github.v3.raw" ", "-L ", ""https://github.com/jajabu33/test/branches""});
                      curl: option -L : is unknown

                      It's -L and not -L , and the quoting of the url is wrong since the url is https://github.com/jajabu33/test/branches and not "https://github.com/jajabu33/test/branches". Same goes for the argument for -H.
                      @JonB already told you this but you ignored him.

                      R Offline
                      R Offline
                      Rua3n
                      wrote on last edited by
                      #13

                      @Christian-Ehrlicher
                      I don't understand what you mean by "already told you this but you ignored him."
                      told what?

                      -L doesnt work either

                      QString output = process("curl", {" -H", "Accept: application/vnd.github.v3.raw", " -L", "https://github.com/jajabu33/test/branches"});
                      curl: (3) URL using bad/illegal format or missing URL
                      

                      QString output = process("curl", {" -H", " Accept: application/vnd.github.v3.raw", " -L", " https://github.com/jajabu33/test/branches"});
                      curl: (3) URL using bad/illegal format or missing URL
                      
                      JonBJ Christian EhrlicherC 2 Replies Last reply
                      0
                      • R Rua3n

                        @Christian-Ehrlicher
                        I don't understand what you mean by "already told you this but you ignored him."
                        told what?

                        -L doesnt work either

                        QString output = process("curl", {" -H", "Accept: application/vnd.github.v3.raw", " -L", "https://github.com/jajabu33/test/branches"});
                        curl: (3) URL using bad/illegal format or missing URL
                        

                        QString output = process("curl", {" -H", " Accept: application/vnd.github.v3.raw", " -L", " https://github.com/jajabu33/test/branches"});
                        curl: (3) URL using bad/illegal format or missing URL
                        
                        JonBJ Online
                        JonBJ Online
                        JonB
                        wrote on last edited by JonB
                        #14

                        @Rua3n
                        In both these cases the extra space in " -H" and " -L" are wrong.

                        I expect

                        QString output = process("curl", {"-H", "Accept: application/vnd.github.v3.raw", "-L", "https://github.com/jajabu33/test/branches"});
                        

                        to work and thought you had shown that it does?

                        1 Reply Last reply
                        0
                        • R Rua3n

                          @Christian-Ehrlicher
                          I don't understand what you mean by "already told you this but you ignored him."
                          told what?

                          -L doesnt work either

                          QString output = process("curl", {" -H", "Accept: application/vnd.github.v3.raw", " -L", "https://github.com/jajabu33/test/branches"});
                          curl: (3) URL using bad/illegal format or missing URL
                          

                          QString output = process("curl", {" -H", " Accept: application/vnd.github.v3.raw", " -L", " https://github.com/jajabu33/test/branches"});
                          curl: (3) URL using bad/illegal format or missing URL
                          
                          Christian EhrlicherC Offline
                          Christian EhrlicherC Offline
                          Christian Ehrlicher
                          Lifetime Qt Champion
                          wrote on last edited by
                          #15

                          @Rua3n said in How to use curl cmd in c++/qt:

                          I don't understand what you mean by "already told you this but you ignored him."

                          @JonB

                          Then each arguments could be passed without quotes

                          Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                          Visit the Qt Academy at https://academy.qt.io/catalog

                          1 Reply Last reply
                          1
                          • jeremy_kJ Offline
                            jeremy_kJ Offline
                            jeremy_k
                            wrote on last edited by
                            #16

                            Rather than continuing to ask for and provide step by step corrections, I suggest using a dummy program in place of curl to show what arguments curl is receiving.

                            #include <cstdio>
                            int main(int argc, char **argv) {
                              for (int i = 0; i < argc; i++) printf("arg %d is '%s'\n", i, argv[i]);
                            }
                            

                            Asking a question about code? http://eel.is/iso-c++/testcase/

                            1 Reply Last reply
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