10.5: Install OS X to a different volume without rebooting

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.

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10.5: Install OS X to a different volume without rebooting
Authored by: rumirocks on Fri, Dec 14 2007 at 11:08AM PST

Thank you!

10.5: Install OS X to a different volume without rebooting
Authored by: tonyo on Fri, Dec 14 2007 at 7:03PM PST

One word: brilliant.

Same in Tiger
Authored by: earthsaver on Sun, Dec 16 2007 at 6:40AM PST

OSInstall.mpkg was in the same place available for the same purpose in Tiger as well.

---
- Ben Rosenthal
PBG4 1.25 - Leopard

10.5: Install OS X to a different volume without rebooting
Authored by: zebrum on Sun, Dec 16 2007 at 8:49AM PST

who said the install pkg wasn't there? How'd they think it installed? magic? LOL

No need to use Terminal
Authored by: sneeper on Sun, Dec 16 2007 at 10:36AM PST

No need to run terminal if you know the path.

Just select "Go to Folder" from the GO menu in finder (or shift-cmd-G) and type <i>/Volumes/Mac OS X Install DVD/System/Installation/Packages/</i>

10.5: Install OS X to a different volume without rebooting
Authored by: ptone on Sun, Dec 16 2007 at 2:46PM PST

It might be mentioned that the pkg format changed enough that you have to be running leopard to run the mpkg installer.

I had first tried this from Tiger, but the installer won't open the new leopard install package.

-P

10.5: Install OS X to a different volume without rebooting
Authored by: daschu on Sun, Dec 16 2007 at 3:41PM PST

Anyone able to confirm that by copying the Installation/Packages folder into the same location on an actual running system, you'd be able to have a fully functional, bootable system that simultaneously includes the necessary files for installation, but none of the files necessary to boot from the DVD?

I think if that is possible, then we'll be one step closer to a single bootable device (such as an old firewire iPod) that can boot, diagnose, and install Leopard on any recent Mac system.

~~~

I would like to also point out that using this hint has the limitation of PPC and Intel Macs not getting along. If trying to run the OSInstall.mpkg from one type of machine for installation on another type of machine, it will complain about the target disc's partition format being incompatible with the computer the installer is being run from. For example: trying to use a PPC to install onto an Intel Mac, the installer will refuse to install because the disk needs to be formatted with the Apple Partition Map, rather than the GUID Partition Table. Although, I've heard reports that Intel Macs will boot from APM disks, its just that "officially" they won't.

10.5: Install OS X to a different volume without rebooting
Authored by: fahirsch on Mon, Dec 17 2007 at 4:26AM PST

Intel macs can and do boot from APM disks. It's the installer that refuses to install if not GUID. This link shows how to make a partitioned bootable HD that can boot on either type of mac.

10.5: Install OS X to a different volume without rebooting
Authored by: sreubart on Mon, Dec 17 2007 at 11:03AM PST

I can verify that you CAN create a drive that will boot either PPC or Intel systems. You have to hook it up to a PPC machine, format it as Apple Partition Map (APM) format, and install Leopard onto the drive.

This has been a godsend, because with Tiger I had to maintain two separate master setup drives. I can do it with just one in Leopard. Thank you, Apple!!!

10.5: Install OS X to a different volume without rebooting
Authored by: Helmuth on Thu, Feb 12 2009 at 1:49PM PST

i´m too stupid to find the file.Neither by using the terminal nor by "Go to folder..." Image is mounted. Does anyone has an idea or have i misunderstood a step. Thanks for your help.

10.5: Install OS X to a different volume without rebooting
Authored by: Dr Happy Mac on Sun, Sep 27 2009 at 10:33AM PDT

Sadly, this hint no longer works in 10.6 Snow Leopard. You can still access the installer package in the same way for either 10.4 or 10.5 and the installer will happily run, complete and announce success. However if you are creating a new install on a fresh drive the drive is rendered non bootable.
I don't know if the same applies to an upgrade to an existing OS.

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