Fork some process and wait for all forks to complete

forkAndWait.bash

#!/bin/bash

PIDS=""
function fork() {
  echo "sleeping ${1}s" && sleep ${1}s && echo "slept ${1}s" &
  PIDS="${PIDS} $!"
}
fork 2
fork 4
fork 8
fork 16

for pid in ${PIDS}; do
    wait ${pid}
done

echo "Complete"