Dec 14, '07 07:30:00AM • Contributed by: syzygies
The file OSInstall.mpkg is the key to Leopard installs from a disk image. There is no need either to use the DVD again, or to reboot, to install Leopard to a different volume. After installing any Mac OS once from DVD, I always use Disk Utility to save the installer DVD as a disk image. Any further installs are from copies of this disk image; I put the original DVD away never to touch it again. I keep many external bootable drives, so the fire never goes out, so to speak.
On OS X install disks, it has always been the case (and remains the case with Leopard) that the top-level Install Mac OS X icon wants to reboot, but buried in the disk is a file named OSInstall.mpkg that can install OS X to a different volume without rebooting.
Reports that this is no longer possible with Leopard are in error. What has changed is that the folder structure is now hidden to the Finder. The needed path is still visible in Terminal, and one can use open in Terminal to reveal folders in the Finder. I then save an alias to OSInstall.mpkg next to each copy of the disk image (Command-Option-drag). Whenever I want to install OS X, I mount the disk image, click on the OSInstall.mpkg alias, and we're off to the races.
The Terminal command to open the enclosing folder for OSInstall.mpkg on a mounted Leopard install disk image is:
open "/Volumes/Mac OS X Install DVD/System/Installation/Packages/"
This was widely known and was easily discovered by poking around for previous versions of OS X; a search here for OSInstall.mpkg reveals many posts about this. What's new in Leopard is that the folder structure is now hidden.
