With the InstallESD.dmg file copied to the Desktop (see page 1), we're ready to create a bootable version of the file on a USB flash drive.
Format the USB Flash Drive
- Insert the USB flash drive into one of your Mac's USB ports.
- Launch Disk Utility, located at /Applications/Utilities.
- In the Disk Utility window that opens, use the sidebar to scroll through the list of storage devices connected to your Mac and locate the USB flash drive. The drive may have one or more volume names associated with it. Look for its top-level name, which is usually the name of the drive's manufacturer. For instance, my flash drive's top-level name is 30.99 GB SanDisk Ultra Media.
- Select the top-level name of your USB flash drive.
- Click the Partition tab.
- From the Partition Layout drop-down menu, select 1 Partition.
- Click the Format drop-down menu and ensure that Mac OS X Extended (Journaled) is selected.
- Click the Options button.
- Select the GUID Partition Table from the list of available partitioning schemes, and then click the OK button.
- Click the Apply button.
- Disk Utility will ask for confirmation that you wish to partition the USB flash drive. Remember, this will erase all of the content on the flash drive. Click the Partition button.
- The USB flash drive will be erased and formatted, and then mounted on your Mac's Desktop.
WARNING: The next series of steps will erase all data on the USB flash drive. Before proceeding, make a backup of the data on the flash drive, if any.
Reveal What Is Hidden
The OS X Mavericks installer has a few hidden files that we need to be able to access in order to make the USB flash drive bootable.
- Follow the instructions in View Hidden Folders on Your Mac Using Terminal to make the hidden files visible.
Mount the Installer
- Double-click the InstallESD.dmg file that you copied to the Desktop earlier.
- The OS X Install ESD file will be mounted on your Mac and a Finder window will open, displaying the contents of the file. Some file names will appear dim; these are the hidden files that are now visible.
- Arrange the OS X Install ESD window and the Disk Utility window so that you can easily see both of them.
- From the Disk Utility window, select the USB flash drive's name in the sidebar.
- Click the Restore tab.
- Drag the BaseSystem.dmg file from the OS X Install ESD window to the Source field in the Disk Utility window.
- Select the USB flash drive volume name (untitled 1) from the Disk Utility sidebar and drag it to the Destination field.
- If your version of Disk Utility contains a box labeled Erase Destination, make sure that box is checked.
- Click Restore.
- Disk Utility will ask for confirmation that you wish to erase the destination volume and replace it with the contents of BaseSystem.dmg. Click Erase to proceed.
- Supply your administrator password, if required.
- Disk Utility will start the copy process. This can take a bit of time, so relax, play a game, or explore some of the other articles on About.com: Macs. When Disk Utility finishes the copy process, it will mount the USB flash drive on the Desktop; the name of the drive will be OS X Base System.
- You can quit Disk Utility.
Copy the Packages Folder
So far, we've created a bootable USB flash drive that contains just enough of a system to allow your Mac to boot. And that's about all it will do until we add the Packages folder from the InstallESD.dmg file to the OS X Base System you just created on your flash drive. The Packages folder contains a series of packages (.pkg) that install various pieces of OS X Mavericks.
- Disk Utility should have mounted your flash drive and opened a Finder window labeled OS X Base System. If the Finder window isn't open, locate the OS X Base System icon on the Desktop and double-click it.
- In the OS X Base System window, open the System folder.
- In the System folder, open the Installation folder.
- Within the Installation folder you'll see an alias with the name Packages. Right-click the Packages alias and select Move to Trash from the pop-up menu.
- Leave the OS X Base System/System/Installation Finder window open; we'll be using it in the next few steps.
- Locate the Finder window called OS X Install ESD. This window should be open from a previous step. If not, double-click the InstallESD.dmg file on the Desktop.
- In the OS X Install ESD window, right-click the Packages folder and select Copy "Packages" from the pop-up menu.
- In the Installation window, move your cursor to a blank area (make sure you're not selecting any item already in the Installation window). Right-click in the blank area and select Paste Item from the pop-up menu.
- The copy process will take a bit of time. Once it's complete, you can close all of the Finder windows, and eject the OS X Install ESD image and the OS X Base System flash drive.
You now have a bootable USB flash drive that you can use to install OS X Mavericks on any Mac you own.
Hide What Should Not Be Seen
The last step is to use Terminal to hide the special system files that shouldn't normally be visible.
- Follow the instructions in View Hidden Folders on Your Mac Using Terminal to make these files invisible again.