block-website

#!/bin/bash
# For easily blocking websites through /etc/hosts
# Example:
#   block reddit.com old.reddit.com # Block old.reddit.com and www.reddit.com
#   block -u reddit.com # Unblock both subdomains (based on suffix)

function block-host {
    HOST="$1"
    if grep -q "^#\?\s*0.0.0.0\s*[[:alnum:]]*\.\?$HOST" /etc/hosts; then
        echo "Uncommenting \*$HOST in /etc/hosts..."
        sudo sed -i "s/^#\s*\(0.0.0.0\s*[[:alnum:]]*\.\?$HOST\)\s*$/\1/g" /etc/hosts
    else
        NUMBER_OF_DOTS="$(echo "$HOST" | tr -d -c '.' | wc -m)"
        if [ $NUMBER_OF_DOTS -eq 0 ]; then
            echo "$HOST is not a domain"
            HOST=""
        else
            if [ $NUMBER_OF_DOTS -eq 1 ]; then
                HOST="www.$HOST"
            fi
            echo "Adding $HOST to /etc/hosts..."
            sudo tee -a /etc/hosts <<< "0.0.0.0     $HOST"
        fi
    fi
}

function unblock-host {
    HOST="$1"
    echo "Commenting \*$HOST in /etc/hosts..."
    sudo sed -i "s/^\s*\(0.0.0.0\s*[[:alnum:]]*\.\?$HOST\)\s*$/#\1/g" /etc/hosts
}

BLOCK=true
HOSTS=( )

for ARG in "$@"; do
    case $ARG in
        -u|--unblock)
            BLOCK=false
        ;;
        *)
            HOSTS+=( "$ARG" )
        ;;
    esac
done

for HOST in "${HOSTS[@]}"; do
    if [ ! -z "$HOST" ]; then
        if [ "$BLOCK" = true ]; then
            block-host "$HOST"
        else
            unblock-host "$HOST"
        fi
    fi
done