Exercise 1: Job Numbers vs. PIDs — Possible Solution
=====================================================

Terminal 1:

  $ sleep 1000 | cat &
  [1] 60412
  $ jobs -l
  [1]+ 60411 Running        sleep 1000
       60412                 | cat &
  $ echo $$
  60380

  Job number: 1
  PIDs:       60411 (sleep) and 60412 (cat) — one job, two processes
  Shell PID:  60380

Terminal 2:

  $ kill %1
  bash: kill: %1: no such job

  $ kill 60411 60412          # use the PIDs instead
  (or: pkill -f "sleep 1000")

Back in terminal 1, the next prompt reports the job as finished.

Why %1 fails in the second terminal: job numbers are kept by the shell
that started the job. The second terminal runs a different shell with
its own, empty job list, so "%1" means nothing there. PIDs are
assigned by the kernel and are valid from anywhere (for processes you
have permission to signal).

WHY THIS WORKS AS AN ANSWER
------------------------------
It shows a single job containing two PIDs, and demonstrates the scope
difference directly with the "no such job" error. PIDs will differ.