There is no real need to keep flipping in and out of the string like that, just use this:
$stringData = "\n\n\$'$hostname = '$hostname\n\$$database = wordlife\n\$$mysql_username = $mysql_username\n\$$mysql_user_password = $mysql_user_password\n\n"; ...or something similar - use double quotes to interpolate the variable values and escape the newlines and literal dollar signs
