How to install Mac OS from a USB stick?

Installing macOS from a USB key has several advantages: it is a solution that can be useful in the event of a failure, if you want to reinstall macOS without an internet connection or to install the OS on several machines in the chain.

To run this tutorial, you will need a USB key or an external hard drive with a capacity of at least 16GB. It is essential to save the files on another disk: the key will be formatted during the tutorial.

Format your USB drive

1. Simultaneously press the keys Cmd + Space to open Spotlight.

   



2. Entrez Disk Utility and launch the utility.


3. Click on the volume to format in the left column and then click on the button Clear.


4. In the parameter Size, select Mac OS Extended (Journaled) . Rename your USB stick with only one word, All Tied Up.


5. Wait until Disk Utility finishes formatting the USB drive.

Download the macOS installer

1. Click on the button Apple at the top left of the screen then on App Store.


2. In the search bar, enter the name of your current operating system (here, macOS Mojave).


3. On the operating system page, click Obtain or on the cloud icon.


4. Click on Download.


5. Wait while the installer is downloaded.


6. Once the installer starts, leave it without installing.

Create a macOS installation USB drive

La Terminal window provides the fastest way to easily create a macOS installation USB drive.

1. Simultaneously press the keys Cmd + Space to open Spotlight.


2. Entrez Port and run it Port.


3. You should see this window open.


4. Copy the following command line, depending on your situation, and then click the Enter key. Note: in the command line, replace "MyUSB" by the name given to your USB key.
   
   For a macOS Mojave installer:
   sudo /Applications/Install macOS Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/MonUSB
   
   For a macOS Mojave installer from macOS Sierra or earlier:
   sudo /Applications/Install macOS Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/MonUSB --applicationpath /Applications/Install macOS Mojave.app
   
   For a macOS High Sierra installer:
   sudo /Applications/Install macOS High Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MonUSB
   
   For a macOS High Sierra installer from macOS Sierra or earlier:
   sudo /Applications/Install macOS High Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MonUSB --applicationpath /Applications/Install macOS High Sierra.app
   
   For a macOS Sierra installer:
   sudo /Applications/Install macOS Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MonUSB --applicationpath /Applications/Install macOS Sierra.app
   
   For a macOS El Capitan installer:
   sudo /Applications/Install OS X El Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/MonUSB --applicationpath /Applications/Install OS X El Capitan.app



5. Enter your mot de passe administrator.


6. Press the key Y then Starter.


7. Wait while the installation files are copied to the USB drive. It may take several minutes.


8. Once the installation files have been copied, you have a bootable usb stick ready to install macOS.

Install macOS from the USB drive

1. Click on the menu Apple at the top left of the screen, then on System Preferences.


2. Click on the menu Boot disks.


3. Select the disk corresponding to your macOS installation USB driveAnd click To restart.


4. After restarting, the computer offers you the following menu. Click on Reinstall macOS and follow the steps of the installation process.

Caution : It is strongly recommended that you back up your personal files before reinstalling macOS. You can do this by using Time Machine to create a save point.

Find other tutorials on Mac:

• How to activate dark mode on Mac?
• How do I create a Mac OS restore point?
• How to install Windows on a Mac with Boot Camp?
• How to reset Mac OS?
• How to update your Mac?