The Mac OS X 10.9 Mavericks download script is now hosted on Mavericks Forever. To download Mavericks, open a Terminal on any Mac and run:
curl mavericksforever.com/get.sh | sh
Or, navigate directly to mavericksforever.com/get.sh to read what the script does.
Oh no, I'm so sorry you lost data!
The USB creation script does need to repartition the entire disk in order to ensure a GUID Partition Table. I've updated the warning message to make this more explicit:
WARNING: Everything on the disk containing $target_volname will be erased. Continue? (yes/no)
The entire reason this part of the script exists is because I kept getting emails from people who ran into trouble doing the restore manually via Disk Utility. Most of these users have no idea what a partition is, or that a disk can have more than one. I do still recommend using Disk Utility for more complex disk layouts.
It's really tricky to come up with phrasing that will accurately inform a more technical user without confusing a less-technical one. Even with the current phrasing, I'm worried some people will think that their entire computer will be erased or something.
Please update this script. Unfortunately, I tried to restore the Mavericks installer using the restore command script to a specific drive partition. It erased the entire drive, I lost a lot of important files.