wait.1 - nroff source : Read wait(I) in pdf, ps, or txt form.
wait - await completion of process
Wait until all processes started with & have completed, and report on
Because wait(II) must be executed in the parent process, the Shell
itself executes wait, without creating a new process.
After executing wait you are committed to waiting until termination,
because interrupts and quits are ignored by all processes concerned.
The only out, if the process does not terminate, is to kill it from
another terminal or to hang up.