#!/bin/bash
function f() {
  sleep "$1"
  echo "$1"
}
while [ -n "$1" ]
do
  f "$1" &
  shift
done
wait

https://monobook.org/wiki/%E3%82%B9%E3%83%AA%E3%83%BC%E3%83%97%E3%82%BD%E3%83%BC%E3%83%88