How to launch the associated application for a file / directory / URL?

Question

Linux seems to be easy: xdg-open .

Apparently, Mac is similar: open should be used

Answer 1

Why don't you just use Qt's support for this? For example:

QDesktopServices::openUrl(QUrl("/home/realnc/test.pdf"));

This opens the document in Acrobat Reader. In general, it obeys the preferred application settings in my OS for all file types that have one or more applications associated with them. Best of all, it's platform-independent.

Edit: The fact that it opens directories on Linux but not on Windows smells like a bug. It might be best to report this on Qt's bug tracker. In the meantime, you could have a workaround for Windows for when the file is a directory:

#ifdef Q_WS_WIN
    if (QFileInfo(path).isDir())
        QProcess::startDetached("explorer", QStringList(path));
    else
#endif
        QDesktopServices::openUrl(QUrl(path));

You can also do it with cmd.exe's start command, but you'll get an ugly terminal pop up for a few fractions of a second:

QProcess::startDetached("cmd", QStringList() << "/C" << "start"
                               << QDir::toNativeSeparators(path));