On a Ubuntu 14.04 machine I set up recently, I noticed that sometimes the CPU consumption in System Monitor was at 30 or 40%, yet in the list of processes, only a few processes were listed as using the CPU, and they added up to maybe 3%.
How can this be? I had some bash scripts running sometimes. I had them either launch on startup or assigned them to keyboard shortcuts and ran them that way. Could those bash scripts have been what was consuming the CPU? If they were written badly or something? Would those bash scripts running in the background not have shown up as processes in the System Monitor?
The machine had an Intel i5 processor with 2.5 Ghz capacity.