How to Create a Bootable OS X Yosemite USB Drive from OS X



Requirements

  1. 8GB+ USB drive with nothing important on it
  2. Computer running OS X

1. In Disk Utility format your USB drive as HFS+

2. Open up a terminal and mount the Yosemite Installer

sudo hdiutil attach /Applications/Install\ OS\ X\ Yosemite.app/Contents/SharedSupport/InstallESD.dmg

3. Restore the Yosemite InstallESD.dmg to your USB drive.  Replace “USBDrive” with the name of your drive.  You will be prompted for a Yes or No.  Hit y and then Enter to continue and erase all the data on the USB drive.

sudo asr restore -source /Volumes/OS\ X\ Install\ ESD/BaseSystem.dmg -target /Volumes/USBDrive -erase -format HFS+

4. Delete and add some packages.

sudo rm /Volumes/OS\ X\ Base\ System/System/Installation/Packages
sudo cp -a /Volumes/OS\ X\ Install\ ESD/Packages /Volumes/OS\ X\ Base\ System/System/Installation/Packages

5. Copy some more files.

sudo cp -a /Volumes/OS\ X\ Install\ ESD/BaseSystem.chunklist /Volumes/OS\ X\ Base/System/
sudo cp -a /Volumes/OS\ X\ Install\ ESD/BaseSystem.dmg /Volumes/OS\ X\ Base/System/

7. Detach the USB Drive

hdiutil detach /Volumes/OS\ X\ Install\ ESD/

8. Plug the drive into a mac and start the installation.

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