focus - blacklists certain websites

focus

#!/bin/bash

################################################################################
# FOCUS
# =====
# Blacklists certain websites.
# 
# How to use:
#   1. Edit the DOMAINS variable with the domains you'd like to blacklist
#   2. run `/path/to/focus start` to start focusing
#   3. run `/path/to/focus stop` to stop focusing
# 
# Usage:
#   focus start    starts focusing
#   focus stop     stops focusing
# 
# Notes:
#   * You should include this script in your PATH so you can run focus from
#     anywhere.
#   * You must include a domain rule for each subdomain (e.g. example.com and 
#     www.example.com).
#   * If you change your domains while you are focusing, you will need to stop
#     focusing and then start again.
#   * If you're running a webserver listening on localhost, blocked websites
#     that you'd normally visit over HTTPS will throw, in most browsers, a SSL
#     certificate error. Rest assured that this is the expected behavior and it
#     will not occur after you stop focusing.
################################################################################

# The domains you want to blacklist
DOMAINS=(example.com www.example.com foobar.com www.foobar.com)

# Other stuff
BEGIN_CAP="# BEGIN focus"
END_CAP="# END focus"
REDIRECT_IP="127.0.0.1"
HOSTS_FILE=/etc/hosts
TMP_FILE=/tmp/focus_hosts

if [[ -n "$1" ]]; then
 
  # start arg
  if [[ "$1" == "start" ]]; then
 
    # Prompt for password
    if [ $EUID != 0 ]; then
     sudo "$0" "$@"
     exit $?
    fi
 
    # First, check if we're already focusing
    if [[ ! -z "$(sed -n "/$BEGIN_CAP/p" /etc/hosts)" ]]; then
      echo "You're already focusing, young padawan."
      exit 0
    fi
 
    # Append domains
    echo "Focusing..."
    echo -e $BEGIN_CAP"\n$(printf "$REDIRECT_IP\t%s\n" "${DOMAINS[@]}")\n"$END_CAP >> $HOSTS_FILE
    sudo dscacheutil -flushcache

  # stop arg
  elif [[ "$1" == "stop" ]]; then
    # Prompt for password
    if [ $EUID != 0 ]; then
     sudo "$0" "$@"
     exit $?
    fi
 
    echo "Stopping..."
    sed "/^$BEGIN_CAP/,/^$END_CAP/d" /etc/hosts > $TMP_FILE
    sudo mv $TMP_FILE $HOSTS_FILE
    sudo dscacheutil -flushcache
  fi
else
  echo -e "Available commands are:\n  focus start\t\tstart focusing\n  focus stop\t\tstops focusing"
fi

exit 0