How to clean install OS X without a USB drive


This way to make a fresh install works for 10.9 (Mavericks) and 10.10 (Yosemite).

Create a bootable partition (5 min)

Open Disk and create a new 16GB partition (Mac OS Extended) at the end of your volume with the name Untitled.

Copy OS X install on it (10 min)

In (in /Applications/Utilities), run the commands below (one by one, adjusting path of the 2 first variables if needed).

Tip: For the first line below, you can copy the app in the Finder and paste in Terminal, this will paste the path if you are getting the Install app somewhere else.

$ OSX_INSTALL_APP="/Applications/Install OS X" $ OSX_INSTALL_DISK="/Volumes/Untitled" $ sudo $OSX_INSTALL_APP/Contents/Resources/createinstallmedia --volume $OSX_INSTALL_DISK --applicationpath $OSX_INSTALL_APP --nointeraction

The last step should take easily take less than 10 minutes (time to copy and adjust entire install app).

You should get something like:

Erasing Disk: 0%... 10%... 20%... 100%... Copying installer files to disk... Copy complete. Making disk bootable... Copying boot files... Copy complete. Done.

Boot from the partition

Just hold option key (alt) when you start your computer, then choose the appropriate partition.

Clean Install

Clean you previous install (1 min)

When you are on the OS X Utilities, choose Disk Utility. From here this time, just erase your partition where you will install OS X (probably Machintosh HD).

I know you know but just in case: you will lose everything on this partition and won't be able to get the content again. Make a backup before. This should take a minute.

Install !

When it's done, just continue the install on the cleaned partition & you should be good.

Not: this method should be able to install a recovery partition if possible.

Bonus: setup your entire machine in a flash

Now time to get Xcode & run it one time (so it install dev & cli tools). Then you can setup your machine using your dotfiles if you have some ;)