#! /bin/sh

usage() {
   echo "Usage: $0 {100|200|300|500|1000|2000|4000} [command [args]]"
   exit 1
}

case "$1" in
   100|200|300|500|1000|2000|4000)
   ;;

   *) usage
   ;;
esac

size="$1" # in megabytes
shift

CGROUPS=/sys/fs/cgroup
echo $$ > "$CGROUPS"/${size}M/tasks || exit 1

ulimit -d ${size}000
exec nice -n 20 ionice -c3 "${@:-$SHELL}"