Yeah I meant locate hdparm.
You can also issue a find command. However, more then likely you are using an up to date Linux distro with the locate utility. It automatically builds a database of all the files on your system once per day I believe. I can't remember off the top of my head and I'm a little sick so don't really feel like looking it up. So just type locate hdparm at the command line. If that doesn't work. Do a find for hdparm. That should point you to the right location for it. Hope that helps. Sorry I'm not as informative as I could otherwise be.