killtree.sh

#!/bin/bash

# usage :
# sudo killtree pid

killtree() {
    local _pid=$1
    kill -STOP ${_pid}
    for _child in $(ps -o pid --no-headers --ppid ${_pid}); do
        killtree ${_child}
    done
    kill -KILL ${_pid}
}

if [ $# -ne 1 ]; then
    echo "Usage: $(basename $0) <pid>"
    exit 1
fi

killtree $@