create_yosemite_bootable_disk.sh

# Since Contents/Resources/createinstallmedia command doesn't work, we need to manually create an disk image.

# Mount InstallESD.dmg
hdiutil mount /Applications/Install\ OS\ X\ 10.10\ Developer\ Preview.app/Contents/SharedSupport/InstallESD.dmg 

# Create a temporary writable BaseSystem image.
hdiutil convert /Volumes/OS\ X\ Install\ ESD/BaseSystem.dmg -format UDRW -o rw.dmg

# Get required sectors for packages.
# You'll get these numbers.
# min       cur       max 
# 10215452  10215452  10215452
hdiutil resize -limits /Applications/Install\ OS\ X\ 10.10\ Developer\ Preview.app/Contents/SharedSupport/InstallESD.dmg

# Get current sectors.
# You'll get these numbers.
# min 	  cur 	  max 
# 2527712 2527712 1312429208
hdiutil resize -limits rw.dmg

# Increase the install image size so that we can write all install packages.
# 10215452 + 2527712 = 12743164
hdiutil resize -sectors 12743164 rw.dmg

# Mount the install image.
hdiutil mount rw.dmg

# Enable ownership on these disks so that we can copy file ownerships.
sudo diskutil enableOwnership /Volumes/OS\ X\ Install\ ESD
sudo diskutil enableOwnership /Volumes/OS\ X\ Base\ System

# Remove an existing symbolic link pointing install packages.
sudo rm /Volumes/OS\ X\ Base\ System/System/Installation/Packages

# Copy packages into the writable install image.
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
sudo cp -a /Volumes/OS\ X\ Install\ ESD/Packages /Volumes/OS\ X\ Base\ System/System/Installation   

# Unmount images.
hdiutil eject /Volumes/OS\ X\ Install\ ESD
hdiutil eject /Volumes/OS\ X\ Base\ System

# Shrink the install image
hdiutil resize -size min rw.dmg

# Convert and compress the install image
hdiutil convert rw.dmg -format UDZO -imagekey zlib-level=9 -o OS\ X\ 10.10\ Developer\ Preview.dmg

# Remove the temporary writable install image.
rm rw.dmg