#!/bin/bash
# Hosts file updater
# Originally written by Andy Short circa 2002
# You will probably need root or su rights to access /etc/hosts
# modified by killermist with (what seem to be) some logical tweaks
# 20090712 alfredo (1) Added checks for required applications;
#                  (2) put 'footprint' text into the modified hosts file.
# Debian users will need the package "sysutils" as this script uses dos2unix
# $ sudo apt-get install sysutils
#
HFSERVER="http://hostsfile.mine.nu.nyud.net"
HFILE="hosts.zip"
ORIGFILE="/etc/hosts.original"

clear
echo "-------------------------------------------------------------"
echo "This script will update your Hosts file to the latest version"
echo "Your original Hosts file will be renamed to $ORIGFILE"
echo "-------------------------------------------------------------"
echo ""

echo "Checking for required applications..."; ABORT=0
echo ... wget    ; builtin type -P wget     &>/dev/null || { echo "wget is missing."; ABORT=1; }
echo ... unzip   ; builtin type -P unzip    &>/dev/null || { echo "unzip is missing."; ABORT=1; }
echo ... dos2unix; builtin type -P dos2unix &>/dev/null || { echo "tofrodos (which contains dos2unix) is missing."; ABORT=1; }
echo ... grep    ; builtin type -P grep     &>/dev/null || { echo "grep is missing."; ABORT=1; }
# this is just to test the test!
#echo ... crap     ; builtin type -P crap     &>/dev/null || { echo "crap is missing."; ABORT=1; }
#echo ABORT is $ABORT
if [ $ABORT != 0 ] ; then 
	echo One or more required applications are missing. Aborting now ...
	exit 1
fi
echo "OK"
echo ""

if [ ! -f "$ORIGFILE" ] ; then
  echo "Backing up your previous hosts file.." 
  cp -v /etc/hosts $ORIGFILE # I like verbose file operations.  Can be less verbose if necessary.
fi

echo "Retrieving $HFILE from $HFSERVER"
echo ""
wget -O /tmp/$HFILE $HFSERVER/$HFILE
unzip -p /tmp/$HFILE | dos2unix > /tmp/hosts
if [ 'grep -c "banner" /tmp/hosts' ];then 
    echo "Downloaded and unpacked $HFILE OK"
    echo "Appending host list to original content"  # which was probably there for a reason, like to make sure localhost worked, and possibly even more stuff if part of a corporate LAN
    #cp -f -u /tmp/hosts /etc/hosts
    cat $ORIGFILE  >/etc/hosts
    echo "" >>/etc/hosts # to make sure the original file ends in a new-line so that 2 entries don't end up on the same line, either causing unexpected behavior or not working at all
    echo "#============================================================="   >>/etc/hosts
    echo "# This hosts file has been modified by the script:"               >>/etc/hosts
    echo "#     $0"                                                         >>/etc/hosts
    echo "# with a list of blocked sites obtained from $HFSERVER"           >>/etc/hosts
    echo "# from the original file now saved as $ORIGFILE"                  >>/etc/hosts
    echo "# As a side-effect of this script, any changes you wish to make"  >>/etc/hosts
    echo "# persistent in the hosts file should be made to $ORIGFILE"       >>/etc/hosts
    echo "# because /etc/hosts will be respawned from that file and the"    >>/etc/hosts
    echo "# new list from the server each time this script runs."           >>/etc/hosts
    echo "#============================================================="   >>/etc/hosts
    cat /tmp/hosts >>/etc/hosts
    rm -fv /tmp/hosts* # again, I like verbose file operations.  I like to know what my system is doing.
    echo "Update process complete"
    #echo "-------------------------------------------------------------"
    echo "As a side-effect of this script, any changes you wish to make"
    echo "persistent in the hosts file should be made to $ORIGFILE"
    echo "because /etc/hosts will be respawned from that file and the "
    echo "new list from the server each time this script runs."
    exit
else
    echo "Update failed"
fi