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c++qtrootsudokde-plasma

How do I distinguish between when user is root vs when user is sudo'd

I'd like to write some Qt code for a KDE app that distinguishes between when a user is root vs when the user has used sudo to request elevated privileges, so the app can display a different message for each use case. Checking for uid == 0 captures both cases, but how do I distinguish between them?

Solution

  • You can read SUDO_USER environment variable using QProcessEnvironment class:

    QProcessEnvironment system_env = QProcessEnvironment::systemEnvironment();
qDebug() << "USER  : " << system_env.value("USER");
qDebug() << "SUDOER: " << system_env.value("SUDO_USER");

    or #include <unistd.h> and use getlogin:

    std::cout << "LOGGED IN USER: " << getlogin() << std::endl;