Whatever escapes

Create El Capitan USB-drive Installer

Posted in: geeky    

Creating USB-installer in the Terminal

This time of year again. A new version of OS X, this time OS X version 10.11, also known as El Capitan. If you have multiple computers to upgrade, you don’t want to download the 6 GB installer on every Mac – you’d want to create some sort of install media.

El Capitan is the third OS X version where the installer ships with the executable createinstallmedia. I’ve covered the procedure of creating a USB-drive installer for both OS X 10.9 Maverics and OS X 10.10 Yosemite. The procedure for OS X 10.11 El Capitan is the same as for the previous versions, so I won’t go into detail.

The steps

  1. Find a USB-drive of some sort. A USB-stick is probably most convenient. You’ll need an 8 GB or larger drive. Format the media as Mac OS X Extended (Journaled) with GUID partition mapping. Name it Untitled.
  2. Download the El Capitan installer from the Mac App Store. Don’t run it after the download finishes.
  3. Open the Terminal (/Applications/Utilities/Terminal) and enter:
sudo /Applications/Install\ OS\ X\ El\ --volume /Volumes/Untitled/ --applicationpath /Applications/Install\ OS\ X\ El\ --nointeraction
Update 2015-11-12: Command corrected for the final release of El Capitan

Type in your administrative password, and wait 15-20 minutes for the process to finish. Hold down ⌥ during startup to boot from the newly created USB installer.

The command is for the El Capitan GM (Golden Master), so you probably need to correct the “El Capitan Install App”-name. Remember tab completion. Start typing the path /Appland press ⇥. Terminal will expand this to /Applications/. Continue with Instand press ⇥ to expand this to the full name of the installer. In my case Install\ OS\ X\ El\ Capitan\ GM\ The backslashes escapes the spaces in the file name. Continue this process all the way down to createinstallmedia.

Homebrew and /usr/local

If you are a Homebrew user, or use other packages that puts stuff into /usr/local/, use the tip from Jim Lindley for clearing out /usr/local/ before upgrading. If you don’t, you’re in for a looong wait.

Happy upgrading!