Creating a bootable USB drive Mac OS X installer can save you time and bandwidth when you have a few Macs you want to update or you want a backup copy of your operating system installer. Fortunately, it’s pretty straight forward to create a USB installer for the latest OS X Yosemite, currently in beta, and the process is the same as OS X 10.9 Mavericks. You will have to apply and be accepted into the OS X Beta program to get access to the early preview of the operating system but this process looks like it will continue to work when OS X 10.10 is released in its final version.
You will need at least an 8GB USB flash drive as after the install there will be 5.13GB used. You will need to download the OS X 10.10 install through the Mac App Store but do not continue with the install. When the download finishes, follow these steps to create your USB bootable drive.
Insert your USB drive to the Mac. Select the drive and format your USB drive as Mac OS X extended (journaled) using Disk Utility.
With an administrator account that has a password set, open up terminal and run this command:
If you’re using the Beta installer:
[bash]sudo "/Applications/Install OS X Yosemite Beta.app/Contents/Resources/createinstallmedia" –volume /Volumes/Untitled –applicationpath "/Applications/Install OS X Yosemite Beta.app" –nointeraction[/bash]
If you’re using the OS X Yosemite Final release:
[bash]sudo "/Applications/Install OS X Yosemite.app/Contents/Resources/createinstallmedia" –volume /Volumes/Untitled –applicationpath "/Applications/Install OS X Yosemite.app" –nointeraction[/bash]
Give it about 20 minutes to complete and your drive will be complete afterwards.
Your USB drive should now be ready to go.
Insert your USB drive into a compatible Mac and hold down the option key while the Mac is booting up.
Select the “Install OS X Yosemite” drive. The boot will continue until it loads the OS X Utilities.
Select Install OS X and continue through the OS X 10.10 install wizard.