How I Upgraded Nearly 100 Macs to El Capitan In An Evening.

Before I implemented a Mac management solution for my new employer, I was faced with the challenge of bringing nearly 100 Macs up to the latest version of OS X, El Capitan. The only management tool I had in my toolkit was creaky old Apple Remote Desktop.

I used Greg Neagle’s createOSXinstallPkg, available from:

https://github.com/munki/createOSXinstallPkg

along with a copy of Install OS X El Capitan.app from the Mac App Store, to create a standard Mac package (pkg) file that encapsulated the OS installer and could be used, either manually via double-clicking, or via the installer command-line utility, to upgrade a Mac.

sudo /path/to/createOSXinstallPkg — source /Applications/Install\ OS\ X\ El\ Capitan.app/

I used ARD’s template functionality to create a template to copy the newly-created package into the /Users/Shared folder on a remote Mac. I then made this the default template, and used ARD to push the nearly-6 GB package to each Mac that needed the upgrade, one-at-a-time (ARD file transfers get logarithmically slower as you increase the number of simultaneous clients you attempt to copy the files to).

Once the package was copied to each Mac, you can utilize either SSH, or ARD’s Send UNIX Command functionality, to initiate the install and restart the Mac to complete the install:

/usr/sbin/installer -pkg /users/Shared/InstallOSX_10.11.4_15E65.pkg -target / ; /sbin/reboot

After 20–40 minutes, depending on the speed of the Mac and whether it had a Solid State Drive or a spinning disk, the Mac would reboot freshly upgraded to El Capitan.

From here I simply used the softwareupdate command (either via ARD’s Send UNIX Command feature, or SSH) to ensure all updates to the new OS had been applied:

/usr/sbin/softwareupdate -i -a

One large caveat with createOSXinstallPkg is that it cannot be run on Macs that are encrypted with FileVault. You must decrypt the volume and restart the client Mac before being able to run the installer package.

There are other things that may be lost during OS X upgrades (Java 1.6 a/k/a 2015–001, some printer drivers, XQuartz) that you may need to install post-upgrade.

I hope that you find this post helpful.