Many time, we want to bring the background program in foreground, then just enter 'fg'. if there are many programs running in fg, then enter "fg %process_number(from jobs)". If I want to kill a foreground job, what I can do is I can write this command "kill PID(process_ID, you can find it out either us ps or using jobs -l)". if even that fails, I can enter this command "kill KILL PID".