Check the current IP vs the previous known IP, mail out any changes uses the PyMailer script

DynamicIPWatcher.sh

#!/usr/bin/env bash

# == User Set ==
    # py_mailer2 location
    mailer='/root/server_scripts/py_mailer/py_mailer2.py'
    # latest ip file location
    latest_known_ip='/root/.ip'
    #to
    to='someone@example.com'
    # Gmail Username / Password
    username='dummy_email'
    password='dummy_email_password'
# ====================================

# Options for sites to get public IP
options=( 'curl -s ifconfig.me' 'curl whatismyip.org' 'wget -qO- ipecho.net/plain' )
# IP Regex
REGEXip="^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}"

# == FUNCTIONS ==
function check_for_assets {
    if [ ! -e ${latest_known_ip} ]; then
        # Filler IP, will evaluage to false.
        echo "No IP file found, creating..."
        echo '255.255.255.0' > ${latest_known_ip}
    fi
    if [ ! -e "${mailer}" ]; then
        echo "No mailer script found, please verify and try again."
        exit
    fi
}

function get_current_ip {
    echo "Obtaining current public IP address..."
    for option in "${options[@]}"; do
        current_ip=`${option}`
        if [[ ${current_ip} =~ ${REGEXip} ]]; then
            break
        fi
    done
}
function get_latest_known_ip {
    echo "Obtaining the last known public IP..."
    latest_ip=`cat ${latest_known_ip}`
}
function notify_if_diff {
    echo "Comparing Current and Latest Known public IPs..."
    if [[ ${current_ip} != ${latest_ip} ]]; then
        echo "New IP found, mailing ${to} with the info."
        echo "${current_ip}" > ${latest_known_ip}
        python ${mailer} \
            -t ${to} \
            -s "Your IP has changed: ${current_ip}" \
            -m "New home IP: ${current_ip}" \
            -u "${username}" \
            -p "${password}"
    else
        echo "Public IP is unchanged."
    fi
    echo "Done!"
}

function main {
    check_for_assets
    get_current_ip
    get_latest_known_ip
    notify_if_diff
}

main