selfcontrol.sh

# -*- sh -*-
#!/usr/bin/env bash

TMPFILE=/tmp/selfcontrol.temp

# remove self control from hosts
cat /etc/hosts | grep -v self-control > $TMPFILE

echo "# self-control" >> $TMPFILE

# if self control ON

if [[ $1 != "on" ]]
   then if [[ $1 != "off" ]]
        then echo "Expecting cmd line arg [on|off]"
             exit 1
        fi
fi

cat ~/.selfcontrol | while read line
do
    if [[ $1 == "on" ]]
    then
        echo 127.0.0.1 $line \# self-control >> $TMPFILE
    fi
done

cp $TMPFILE /etc/hosts
rm $TMPFILE

before using, you'll need to: sudo chown $USER /etc/hosts

also you need a file called ~/.selfcontrol with newline separated domain names

to activate filter:
$ selfcontrol on

to remove filter
$ selfcontrol off