[linux] "Failed to load platform plugin "xcb" " while launching qt5 app on linux without qt installed

I like the solution with qt.conf.

Put qt.conf near to the executable with next lines:

[Paths]
Prefix = /path/to/qtbase

And it works like a charm :^)

For a working example:

[Paths]
Prefix = /home/user/SDKS/Qt/5.6.2/5.6/gcc_64/

The documentation on this is here: https://doc.qt.io/qt-5/qt-conf.html