A reader who wishes to maintain her anonymity is preparing an old Mac for sale. She writes:
After I purchase a new MacBook I intend to sell my old iBook. How do I clean off my old laptop after I’ve validated that everything moved correctly? I have the original installation discs, but won’t that require the establishment of a user account when I install the OS? I want the machine to have no traces of my usage, but be bootable and ready for use for anyone who gets it. Also, if I do a fresh install, then I’d need to run the last Tiger combo updater. But how do I do that when setting up internet access might leave traces of my setup credentials?
Before we get to installation of the OS let’s back up a couple of steps to make sure that you’ve thought about everything you need to do before putting up this venerable Mac for sale.
First, of course, is that you need to get your data off it and on to your new Mac. The easiest way to do this is to use Migration Assistant, which will make its presence known when you set up your new Mac. To transfer data between the two Macs you'll need either a FireWire connection (you’ll required a FireWire 400-to-800 cable to accommodate the old FireWire 400 port on the iBook and the FireWire 800 port on the MacBook) or a network connection. FireWire will be faster.
If you’ve used your iBook to purchase content from the iTunes Store, be sure to launch iTunes on it and choose Deauthorize This Computer from iTunes’ Store menu. That way you won’t lose one of your five authorizations when you wipe the iBook’s drive.
Once your data is ensconced on the new Mac and your iTunes account is clear, wipe the iBook’s drive by inserting your original installation disc, booting from it (restart and hold down the C key), and choosing Disk Utility from the Installer menu. Within Disk Utility select the Erase tab and in the resulting pane click on the Security Options button. In the pane that appears you have the option to wipe your drive’s data in a number of ways, including Zero Out Data, 7-Pass Erase, and 35-Pass Erase. 7-Pass Erase should certainly wipe your drive but if you’re really, really concerned, choose 35-Pass Erase and wait a long time for Disk Utility to thoroughly wipe your drive. (The more passes, the longer the operation takes.)
When Disk Utility finishes wiping the data from the drive, run the installer to install a clean copy of OS X. When the Mac reboots and prompts you to set it up, just press Command-Q to quit the installer. This ensures that you leave no traces on the iBook and that the new owner can set it up to their liking. You don't need to worry about installing the latest and greatest OS updates on the iBook. After they set up the Mac, Software Update will appear and inform them of any available updates.