You can run macOS on a Mac in a variety of ways that we have already written an informative article about. In this article, we will focus on Mac startup mode with booting from a USB or an external hard drive.

Boot Mac from USB Option l: Startup Manager. If your Mac won't boot up normally, you can set it to boot from a different drive, such as a USB stick containing macOS installation files in bootable format. The drive will have to contain a version of the OS that is compatible with the Mac. As long as you have the bootable installation USB, you can. Method 2: Run “createinstallmedia” in Terminal. Assuming you’ve downloaded the macOS Monterey installer, you can go ahead and run the “createinstallmedia” command in Terminal to create a bootable USB drive: Connect a suitable USB drive to your Mac. Launch Disk Utility from Applications Utilities and write down the name of the USB drive. Aug 20, 2016 Now, click on the “Erase” button and the Disk Utility will prepare the USB stick for the next steps you’re going to follow. Disk Utility will let you know when it’s completed the task; once it’s finished, close Disk Utility. Make a Bootable USB Stick. Next, you’re going to head on over to the Mac App Store on a Mac laptop or computer. How to Boot Mac from USB Media: After creating a bootable USB drive, the user simply needs to plug the created drive into the open port on the Mac. Here are the steps to boot Mac from the USB flash drive: Power on the system. Press and hold the Option (Alt) key on the keyboard when the computer starts.


Starting a Mac with booting from an external disk may be necessary if you need to run another version or copy of macOS, other OS, fix any problems, and so on.

To start the following conditions must be met:

Mac Terminal Boot From Usb
  • The computer is based on the Intel system;
  • The volume is formatted with the choice of GUID section type;
  • Mac OS X v10.4.5 or later is installed on the USB storage device.
Mac terminal bootable usb

Read more:How to Use a External Hard Drive for Time Machine Backups?

How to Boot Mac from an external Hard Drive or USB device?

  • Connect a USB flash drive or external hard drive to your Mac.
  • Turn on your Mac by pressing the power button or restart your computer if it is already running;
  • Hold down the horkey for boots options: Option (Alt) key on the keyboard and hold until the boot menu appears;
  • Select the desired volume using the mouse, arrow or trackpad;
  • Press the Enter key to boot the Mac from the selected volume.
Mac Terminal Boot From Usb


If Mac won’t boot from USB or volume is not displayed, wait a few seconds for the Download Manager to finish scanning the connected disks or use next tips, if it’s useless here the list of troubleshooting.

macOS does not Boot from an External Drive, what Should I Do?

  • Some older external USB drives require additional power. It is possible that it must be connected to an external power source or use a second USB on a Mac;
  • Make sure the external drive is turned on (again, the prerogative of old USB-drives);
  • Restore the disk access rights and correct the errors on it;
  • Make sure the disk is formatted with the choice of partition type GUID;
  • Try connecting an external drive to another USB port;
  • Make sure the external drive is bootable;
  • Connect the drive directly, without using a USB hub.

These advanced steps are primarily for system administrators and others who are familiar with the command line. You don't need a bootable installer to upgrade macOS or reinstall macOS, but it can be useful when you want to install on multiple computers without downloading the installer each time.

What you need to create a bootable installer

  • A USB flash drive or other secondary volume formatted as Mac OS Extended, with at least 14GB of available storage
  • A downloaded installer for macOS Big Sur, Catalina, Mojave, High Sierra, or El Capitan

Download macOS

  • Download: macOS Big Sur, macOS Catalina, macOS Mojave, or macOS High Sierra
    These download to your Applications folder as an app named Install macOS [version name]. If the installer opens after downloading, quit it without continuing installation. To get the correct installer, download from a Mac that is using macOS Sierra 10.12.5 or later, or El Capitan 10.11.6. Enterprise administrators, please download from Apple, not a locally hosted software-update server.
  • Download: OS X El Capitan
    This downloads as a disk image named InstallMacOSX.dmg. On a Mac that is compatible with El Capitan, open the disk image and run the installer within, named InstallMacOSX.pkg. It installs an app named Install OS X El Capitan into your Applications folder. You will create the bootable installer from this app, not from the disk image or .pkg installer.

Use the 'createinstallmedia' command in Terminal

  1. Connect the USB flash drive or other volume that you're using for the bootable installer.
  2. Open Terminal, which is in the Utilities folder of your Applications folder.
  3. Type or paste one of the following commands in Terminal. These assume that the installer is in your Applications folder, and MyVolume is the name of the USB flash drive or other volume you're using. If it has a different name, replace MyVolume in these commands with the name of your volume.

Big Sur:*

Mac Terminal Boot From Usb Windows 7



High Sierra:*

El Capitan:

* If your Mac is using macOS Sierra or earlier, include the --applicationpath argument and installer path, similar to the way this is done in the command for El Capitan.

After typing the command:

  1. Press Return to enter the command.
  2. When prompted, type your administrator password and press Return again. Terminal doesn't show any characters as you type your password.
  3. When prompted, type Y to confirm that you want to erase the volume, then press Return. Terminal shows the progress as the volume is erased.
  4. After the volume is erased, you may see an alert that Terminal would like to access files on a removable volume. Click OK to allow the copy to proceed.
  5. When Terminal says that it's done, the volume will have the same name as the installer you downloaded, such as Install macOS Big Sur. You can now quit Terminal and eject the volume.

Use the bootable installer

Boot From Usb Fat32

Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:

Apple silicon

  1. Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing.
  2. Turn on your Mac and continue to hold the power button until you see the startup options window, which shows your bootable volumes.
  3. Select the volume containing the bootable installer, then click Continue.
  4. When the macOS installer opens, follow the onscreen instructions.

Intel processor

  1. Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing.
  2. Press and hold the Option (Alt) ⌥ key immediately after turning on or restarting your Mac.
  3. Release the Option key when you see a dark screen showing your bootable volumes.
  4. Select the volume containing the bootable installer. Then click the up arrow or press Return.
    If you can't start up from the bootable installer, make sure that the External Boot setting in Startup Security Utility is set to allow booting from external media.
  5. Choose your language, if prompted.
  6. Select Install macOS (or Install OS X) from the Utilities window, then click Continue and follow the onscreen instructions.

Learn more

A bootable installer doesn't download macOS from the internet, but it does require an internet connection to get firmware and other information specific to the Mac model.

For information about the createinstallmedia command and the arguments you can use with it, make sure that the macOS installer is in your Applications folder, then enter the appropriate path in Terminal: