Jobs running in the foreground are suspended by typing Ctl-z (Control-z). So instead of waiting for the long-running split command to complete, it is interrupted using Ctl-z:
$ split —5000 hugefile Ctl-z  + Stoppedsplit —5000 hugefile $
Stopped and backgrounded jobs are brought back into the foreground with the fg command. If no argument is given, the current (most recently stopped or backgrounded) job is used. The stopped split job is brought back into the foreground with fg:
$ fg split —5000 hugefile
Stopped jobs are put into the background with the bg command. If no argument is given, the most recently stopped job is used. In the next example, we want to put the split job back in the background. It is currently running ...