A quick shell script that will automatically update a Linux HOSTS file to block ads and malicious domains.

update-hosts.sh

#!/usr/bin/env sh

# Filename: update-hosts.sh
# Author: George Lesica <george@lesica.com>
# Description: Replaces the HOSTS file with a customized version that blocks
# domains that serve ads and malicious software, creating a backup of the old
# file.

HOSTS_URL="http://someonewhocares.org/hosts/zero/hosts"
NEW_HOSTS="hosts"
HOSTS_PATH="/etc/hosts"

# Check for root
if [ "$(id -u)" -ne "0" ]; then
    echo "This script must be run as root" 1>&2
    exit 1
fi

# Grab hosts file
wget -O $NEW_HOSTS $HOSTS_URL

# Backup old hosts file
cp -v $HOSTS_PATH ${HOSTS_PATH}.bak$(date -u +%s)
cp -v $NEW_HOSTS $HOSTS_PATH

# Clean up old downloads
rm $NEW_HOSTS*

I forked your script and I added the support of multiple hosts sources, initial host file and others fixes: https://gist.github.com/Eliastik/f4a3573b43839c64c35b5e80491aa074

How can I run this script without being prompted for root?
I want to set this up so it can update the hosts file once a day.

@CHJ85 Check my answer here: https://gist.github.com/Eliastik/f4a3573b43839c64c35b5e80491aa074?permalink_comment_id=4579630#gistcomment-4579630

Another option that preserves existing entries instead of overwriting /etc/hosts: https://gist.github.com/metametapod/4c4a7a9c888343fc6e722f8ed77aa763