I would want to compile existing software into presentation that can later be run on different architectures (and OS).
For that I need a (byte)code that can be easily ru
As Ankur mentions, C++/CLI may be a solution. You can use Mono to run it on Linux, as long as it has no native bits. But unless you already have a code base you are trying to port at minimal cost, maybe using it would be counter productive. If it makes sense in your situation, you should go with Java or C#.
Most people who go with C++ do it for performance reasons, but unless you play with very low level stuff, you'll be done coding earlier in a higher level language. This in turn gives you the time to optimize so that by the time you would have been done in C++, you'll have an even faster version in whatever higher level language you choose to use.