force Steam offline using cgroup

#!/bin/bash

echo "testing for sudo"
sudo date
if [ $? -ne 0 ]
then
    echo "failed sudo"
    return -1
fi

PIDFILE=steam.pid

if [[ -z `cat $PIDFILE` ]]
then
    STEAMCGROUP=/sys/fs/cgroup/net_cls/steamblock
    if [ ! -d $STEAMCGROUP ]
    then
        sudo mkdir -p $STEAMCGROUP
    fi
    sudo echo 42 | sudo tee $STEAMCGROUP/net_cls.classid
    sudo iptables -A OUTPUT -m cgroup --cgroup 42 -j DROP


    nohup steam > steam.log &
    echo "waiting for steam start"
    for i in {1..10}
    do
        echo "."
        sleep 1
    done
    steamPIDs=$(pidof steam | tr " " "\n")
    > $PIDFILE
    for pid in $steamPIDs
    do
        echo $pid >> $PIDFILE
        for subpid in $(pstree -p $pid | grep -o '([0-9]\+)' | grep -o '[0-9]\+')
        do
            echo $subpid >> $PIDFILE
        done
    done

    for pid in $(cat $PIDFILE)
    do
        echo $pid | sudo tee $STEAMCGROUP/tasks
    done
else
    # for pid in `cat $PIDFILE`
    # do
        # echo $pid | sudo tee /sys/fs/cgroup/net_cls/tasks
    # # done
    > $PIDFILE
    sudo killall steam
fi

Great for steam library sharing...