Bootable Installer

In my previous article on upgrading my Tech Drive I mentioned cloning over various OS X installers onto partitions on the drive. While I was doing this I realized I did not have a Yosemite or El Capitan installer on my old Tech Drive. This led me to finding a procedure for making a bootable OS X installer.

I have done this in the old days using the Disk Utility app and making a bunch of Disk Images and jumping through a bunch of hoops. I have used third party apps as well, although there are times when these apps are a little buggy. When I discovered this procedure I knew I was home free.

Step 1 – The OS X Installer

Making a bootable installer for a version of OS X is pretty easy. Again, I keep these older OS X versions around to install on older Macs. The very first thing you must do is go into the App Store “Purchased” area and find the OS X version you want:

In this case I have selected OS X Mountain Lion. Then download it to your machine like you are going to install it. When it is finished downloading it will either say something like “this version is too old to install” or it will start going into the install screen. Either way, just quit the install. Now you have that version of OS X in your Applications folder ready to be used. In the normal install process, the version you download will install and the installer disappears from your Applications folder.

Once you have your preferred version of OS X in the Applications folder you need to format and prepare your hard drive partition or USB thumb drive.

Step 2 – The Media

Where are you placing this OS X installer? Many people like to use a thumb drive, which is cool, but they are a bit slow to be sure. The thumb drive needs to be at least 8GB in size. If you are using a Tech Drive or some type of USB hard drive then make sure you have your partition setup (I made my OS X partitions 10GB each). I have found that the procedure we are going to use prefers the name of the partition or thumb drive to have no spaces. That name is going to be changed by the installer by the way.

Once the media is setup then you can go onto the Terminal App part of this procedure that actually makes the bootable installer. Don’t panic! Yes, we are using the Terminal, but this is really easy if you do it by the numbers.

Step 3 – Bootable Installer

When you get to this step then just navigate to this page on the Apple website for further instructions. Apple makes it pretty easy. On this web page you will see an “Examples” section. If you wish to make an El Capitan installer for instance then click in the El Capitan example and copy all that information to the clipboard.

I tried pasting this info into Terminal but it would not let me edit it so you are going to open the Text Edit app and paste it in there. Here is what you will get:

You see where I highlighted the word “MyVolumes”? You are going to type in the exact name of your OS X drive partition or the name you have given to your Thumb drive in place of “MyVolumes”. Then select all of that text in the Text Edit window and copy it to the clipboard.

Next, you need to open the Terminal App (Applications/Utilities Folder/Terminal) from your Utilities folder. Now paste in the text from Text Edit:

Once you hit return it will ask you for your password. Obviously, your thumb drive or your partition are mounted on your system already. The next thing it does is tell you it has to erase that disk. You just need to hit the “Y” key for yes and it formats and installs the version of OS X you have chosen using the “Install” from your Applications folder (you already downloaded it in there in Step 1). Once it is finished it presents this window:

If you look on your Thumb drive or partition you will see it has changed the name a bit. The best thing to do here is to test this installer by booting from it. If it is a Thumb drive it may take a while. You don’t have to install it, just click through a couple of screens to make sure it is going to work, then quit it.

As I mentioned, I discovered I did not have any installer partitions on my Tech Drive for Yosemite or El Capitan so after downloading them both to my Applications folder I used the above procedures to make bootable installers. I booted into them, they both work just fine.


If you are in the market for a bootable installer of some version of OS X then use this method. It is not that difficult, especially after you have done it once. If you are not into the tech repair game, then you might just want to keep a version of the latest Mac OS arond on general principles.