It looks like the compilation process just crashes. Could it be you don't have enough RAM? Building the core setting unfortunately takes quite a bit of memory, since it's such a gigantic piece of code.
Try re-running with a swap file maybe? Alternatively, cd into the rakudo folder that rakudobrew created for you (somewhere under ~/.rakudobrew/moar maybe?) and run the command manually: home/luca/.rakudobrew/moar-nom/install/bin/moar \ --libpath="/home/luca/.rakudobrew/moar-nom/install/share/nqp/lib" \ perl6.moarvm --setting=NULL --ll-exception --optimize=3 --target=mbc \ --stagestats --output=CORE.setting.moarvm gen/moar/m-CORE.setting maybe even under GDB. That should give you a little more detail on what's going on. - Timo
