sudo /Applications/Install\ OS\ X\ El\ Capitan\ Developer\ Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ El\ Capitan\ Developer\ Beta.app --nointeraction
sudo /Applications/Install\ OS\ X\ El\ Capitan\ Public\ Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ El\ Capitan\ Public\ Beta.app --nointeraction
The Terminal window displays createinstallmedia’s progress as a textual representation of a progress bar: Erasing Disk: 0%... 10 percent...20 percent... and so on. You also see a list of the program’s tasks as they occur: Copying installer files to disk... Copy complete. Making disk bootable... Copying boot files... Copy complete. The procedure can take as little as a couple minutes, or as long as 20 to 30 minutes, depending on how fast your Mac can copy data to the destination drive. Once you see Copy Complete. Done., as shown in the screenshot above, the process has finished.
Createinstallmedia will have renamed your drive from Untitled to Install OS X El Capitan Developer Beta or Install OS X El Capitan Public Beta, depending on which version of the installer you used. You can rename the drive (in the Finder) if you like—renaming it won’t prevent it from working properly.
Booting from the installer drive
You can boot any El Capitan-compatible Mac from your new installer drive. First, connect the drive to your Mac. Then, if your Mac is already booted into OS X, choose the installer drive in the Startup Disk pane of System Preferences and restart; or, if your Mac is currently shut down, hold down the Option key at startup, choose the installer drive when OS X’s Startup Manager appears, and click the arrow below that drive to proceed with startup.
Once booted from your installer drive, you can perform any of the tasks available from the OS X installer’s special recovery and restore features. In fact, you'll see the same OS X Utilities screen you get when you boot into OS X Recovery—but unlike with recovery mode, your bootable installer includes the entire installer.
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