Use existing Drupal database

gistfile1.sh

#!/bin/bash
if [ "$#" -ne  "3" ]
  then
    echo "Please supply exactly three arguments:"
    echo ""
    echo " (1) the database username"
    echo " (2) the database password, or NOPWD if none"
    echo " (3) the database name"
else
    if [ "$2" == "NOPWD" ]; then
        PASS=""
    else
        PASS="$2"
    fi 
    echo '$'"databases = array ( 'default' => array ( 'default' => array ( 'database' => '$3', 'username' => '$1', 'password' => '$PASS', 'host' => 'localhost', 'port' => '', 'driver' => 'mysql', 'prefix' => '')),);" >> sites/default/settings.php
fi