How to Create a Bootable OS X USB Key
With OS X Mavericks and Yosemite, you can create a bootable OS X installer which can be used to install the operating system while started from removable media, such as a USB flash drive.
- Download the OS X Installer app from the Mac App Store.
- Mount the volume you want to convert into a bootable installer. This could be removable media such as a USB flash drive, or a secondary internal partition.
- You can then use the createinstallmedia tool to convert the volume from step two into a bootable installer based off the installer app from step one. To learn how to use createinstallmedia, use the following command in Terminal:
OS X Yosemite
/Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmediaOS X Mavericks
/Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia
Examples
For example, assuming you have a volume mounted at /Volumes/SANDISK64GB and the OS X installer app is at /Applications/Install\ OS\ X\ Mavericks.app you could erase /Volumes/SANDISK64GB and convert it into a bootable installer with this command:
OS X Yosemite
sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/SANDISK64GB --applicationpath /Applications/Install\ OS\ X\ Yosemite.app
OS X Mavericks
sudo /Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia --volume /Volumes/SANDISK64GB --applicationpath /Applications/Install\ OS\ X\ Mavericks.app
Example Output From Terminal Below
MacbookPro:~ user$ sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia –volume /Volumes/SANDISK64GB –applicationpath /Applications/Install\ OS\ X\ Yosemite.app
Password:
Ready to start.
To continue we need to erase the disk at /Volumes/SANDISK64GB.
If you wish to continue type (Y) then press return: Y
Erasing Disk: 0%… 10%… 20%… 30%…100%…
Copying installer files to disk…
Copy complete.
Making disk bootable…
Copying boot files…
Copy complete.
Done.
MacbookPro:~ user$
