BASH program that waits until given PIDs have terminated. Rename to pwait and chmod +x.

pwait.sh

#!/bin/bash

if [ $# -eq 0 ]; then
  echo "Usage: pwait <PID>"
  echo "Waits until PID has terminated, then continues."
  echo "Example: pwait 123 && echo DONE"
  exit 1
fi

for pid in "$@"; do
  while [ -e /proc/$pid ]; do
    sleep 0.1
  done
done