Four months ago, Apple released the Yosemite Developer Preview. At that time, I went through the steps to create a USB installer that would copy the installation files necessary to install OS X 10.10.
While the steps varied slightly from previous versions of OS X, it was still an involved process to get the files from the 5 GB+ installer to a USB Flash Drive.
Luckily, there's a simpler way to extract the files from the installer and copy them directly to a bootable USB drive in one fell swoop by using the Terminal.
Before proceeding, review the requirements below prior to creating a USB installer.
- Apple computer running OS X 10.6.8+
- iTunes account
- Install OS X Yosemite.app (Mac App Store)
- Full administrative rights to execute commands in Terminal
- USB Flash Drive (or SD Card) with a minimum of 8 GB storage space
Let's take a look at how to create the USB installer for OS X Yosemite, the easy way.
- Insert the USB Flash Drive or SD Card into the Mac, and make a note of the drive label given to the removable media.
- Launch Terminal.app from the Applications\Utilities folder.
- By default, Mac App Store downloads the Install OS X Yosemite.app file to the Applications folder. In the Terminal, enter the command
sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia —volume /Volumes/DRIVE_LABEL —applicationpath /Applications/Install\ OS\ X\ Yosemite.app —nointeraction
and reference the default save location (Figure A).
- Removable media, when inserted into a Mac, will display a volume name. For the command to execute properly, the label assigned to the device must be entered in place of "DRIVE_LABEL." Once this has been corrected, press the Enter key, and you'll be prompted to enter the administrative password.
- Enter the password, press Enter again, and the process will begin by initializing the drive, which will erase its contents and partition it accordingly (Figure B).
- Next, the installation files will be copied to the drive (Figure C).
- The boot files will also be copied to the drive to make the device bootable (Figure D).
- When the copying process is complete, the word "Done" will appear on the terminal screen. Depending on the specs of your computer, this process can take about 30 minutes on average to complete. Do not remove or quit the task until the word "Done" is displayed, or the drive may not work properly (Figure E).
- With the drive created, insert it into a Mac and try to boot to it by holding down the Option key and selecting it from the boot menu. If working properly, the drive will take you to the OS X installation screen to perform a clean install of OS X Yosemite.
While this process is on-par with the amount of time needed to create a USB installer using the previous method, a one-step creation process using the Terminal is easier to accomplish than the multi-step process.
The process highlighted here will require admin credentials to complete, while the previous process only requires an admin account if the USB Flash Drive must be partitioned — otherwise, the process may be performed as a standard user. Depending on your situation, knowing both methods could have its advantages in the field.
Jesus Vigo is a Network Administrator by day and owner of Mac|Jesus, LLC, specializing in Mac and Windows integration and providing solutions to small- and medium-size businesses. He brings 19 years of experience and multiple certifications from several vendors, including Apple and CompTIA.