Add usage to script

[kodmanyagha]

I think this proxy.sh's feature should be inside of Cpanel but they didn't add this feature still. But no problem, I'm using your script well. But I want to add a small change in this script. Please can you add an "usage" message to script? For example:

#!/bin/bash
echo "========================================================="
echo "==!! cPanel Apache Reverse Proxy !!=="
echo "==!! Usage: proxy.sh {account_username} {subdomain/domain} {local_proxy_path}"
echo "========================================================="
echo ""
DOMAIN=$2
USER=$1
LOCAL=$3

if [[ -z "$USER" ]]; then
    echo "Usage: proxy.sh {account_username} {subdomain/domain} {local_proxy_path}"
    echo "Set a valid cPanel User "
    exit 1
fi

if [[ -z "$DOMAIN" ]]; then
    echo "Usage: proxy.sh {account_username} {subdomain/domain} {local_proxy_path}"
    echo "Set a valid Domain Name"
    exit 1
fi

if [[ -z "$LOCAL" ]]; then
    echo "Usage: proxy.sh {account_username} {subdomain/domain} {local_proxy_path}"
    echo "Set a valid Local Proy Path"
    exit 1
fi

Something like that. Thanks.