An external drive that you can use as an installer for macOS Catalina is a handy thing to have. If you have multple Macs to upgrade, it’s a lot more efficient to plug in the USB installer drive. Blank hard drive - Find a USB external hard drive that holds at least 100 gigabytes (this is where you'll install your macOS stuff, so the bigger, the better). USB-C adapter - If you're working with a Mac that doesn't have traditional USB ports, you'll need a USB-C-to-USB-3.0 adapter.

Click Install macOS and choose to install it from the selected USB drive. Click on “Install macOS” How do I regularly install macOS Big Sur? The regular install is done via upgrading your current macOS. That is, you don’t erase your entire disk. When the new macOS Big Sur is officially released, you just open the App Store Updates. Using Your Bootable macOS USB From the macOS Utilities screen, you can perform a fresh install of macOS, restore from a Time Machine backup, or access tools like Disk Utility. You can also use your USB drive to upgrade macOS to the latest version. Plug in a USB drive, attach it VirtualBox, then EJECT it. Go to Settings ⇨ Ports ⇨ USB ⇨ USB 3.0 xHCI ⇨ Add your USB drive/reader Download, Boot, and Install Ubuntu Desktop 18.04 LTS Start the VirtualBox machine and select `ubuntu-xxx.iso` as the boot disk.

Apple hasn’t shipped operating systems on physical media in a full decade, but there are still good reasons to want a reliable old USB stick for macOS Catalina. Luckily, it's not hard to make one—either with a handy graphical user interface or some light Terminal use. Here's what you need to get started:

  • A Mac that you have administrator access to. We've created a USB stick from both Mojave and Catalina, but your experience with other versions may vary.
  • A 16GB or larger USB flash drive or a 16GB or larger partition on some other kind of external drive. A USB 3.0 drive will make things significantly faster, but an older USB 2.0 drive will work in a pinch; 8GB drives worked for Mojave and older versions of macOS, but the Catalina installer is just a little too large to fit.
  • The macOS 10.15 Catalina installer from the Mac App Store (in High Sierra or older macOS versions) or the Software Update preference pane in Mojave. The installer will delete itself when you install the operating system, but it can be re-downloaded if necessary.
  • If you want a GUI, take a look at Ben Slaney's Install Disk Creator from MacDaddy. There are other apps out there that do this, but this one is quick and simple.

If you want to use this USB installer with newer Macs as they are released, you'll want to periodically re-download new Catalina installers and make new install drives. Apple rolls support for newer hardware into new macOS point releases as they come out, so this will help keep your install drive as universal and versatile as possible.

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There's also one new consideration for newer Macs with Apple's T2 controller chip—as of this writing, that list includes the iMac Pro, the 2018 Mac Mini, the 2018 MacBook Air, and 2018 and 2019 MacBook Pros, though Apple keeps an updated list here. Among this chip's many security features is one that disallows booting from external drives by default. To re-enable this feature, hold down Command-R while your Mac reboots to go into Recovery Mode and use the Startup Security Utility to 'allow booting from external media.' If you're trying to install an older version of macOS, you may also need to go from Full Security to Medium Security to enable booting, but if you're just trying to install the current version of macOS, the Full Security option should be just fine. And if you're just doing an upgrade install rather than a clean install, you can run the Catalina installer from the USB drive from within your current installation of macOS, no advanced tweaking required.

The easy way

Once you've obtained all of the necessary materials, connect the USB drive to your Mac and launch the Install Disk Creator. This app is basically just a GUI wrapper for the terminal command, so it should be possible to make install disks for versions of macOS going all the way back to Lion. In any case, it will work just fine for our purposes.

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Install Disk Creator will automatically detect macOS installers on your drive and suggest one for you, displaying its icon along with its path. You can navigate to a different installer if you want, and you can also pick from all the storage devices and volumes currently connected to your Mac through the drop-down menu at the top of the window. Once you're ready to go, click 'Create Installer' and wait. A progress bar across the bottom of the app will tell you how far you have to go, and a pop-up notification will let you know when the process is done. This should only take a few minutes on a USB 3.0 flash drive in a modern Mac, though using USB 2.0 will slow things down.

The only slightly less-easy way

The Install Disk Creator is just a wrapper for the terminal command to create macOS install disks, so if you’re comfortable formatting your USB drive yourself and opening a Terminal window, it’s almost as easy to do it this way. Assuming that you have the macOS Catalina installer in your Applications folder and you have a Mac OS Extended (Journaled)-formatted USB drive (which is to say, HFS+ and notAPFS) named 'Untitled' mounted on the system, you can create a Catalina install drive using the following command.

sudo /Applications/Install macOS Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled

The command will erase the disk and copy the install files over. Give it some time, and your volume will soon be loaded up with not just the macOS installer but also an external recovery partition that may come in handy if your hard drive dies and you're away from an Internet connection. If you would like to create an install drive for a macOS version other than Catalina, just tweak the paths above to refer to Mojave or High Sierra instead.

Whichever method you use, you should be able to boot from your new USB drive either by changing the default Startup Disk in System Preferences or by holding down the Option key at boot and selecting the drive. Once booted, you'll be able to install or upgrade Catalina as you normally would. You can also use Safari, Disk Utility, or Time Machine from the recovery partition to restore backups or troubleshoot.

Start up from macOS Recovery

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

  • Apple silicon: Turn on your Mac and continue to press and hold the power button until you see the startup options window, which includes a gear icon labeled Options. Select Options, then click Continue.
  • Intel processor: Make sure that your Mac has a connection to the internet. Then turn on your Mac and immediately press and hold Command (⌘)-R until you see an Apple logo or other image.

If you're asked to select a user you know the password for, select the user, click Next, then enter their administrator password.

Reinstall macOS

Select Reinstall macOS from the utilities window in macOS Recovery, then click Continue and follow the installer's instructions.

Follow these guidelines during installation:

  • Allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart and show a progress bar several times, and the screen might be empty for minutes at a time.
  • If the installer asks to unlock your disk, enter the password you use to log in to your Mac.
  • If the installer doesn't see your disk, or it says that it can't install on your computer or volume, you might need to erase your disk first.
  • If the installer is for a different version of macOS than you expected, learn about other installation options, below.
  • If the installer offers you the choice between installing on Macintosh HD or Macintosh HD - Data, choose Macintosh HD.

After installation is complete, your Mac might restart to a setup assistant. If you're selling, trading in, or giving away your Mac, press Command-Q to quit the assistant without completing setup. Then click Shut Down. When the new owner starts up the Mac, they can use their own information to complete setup.

Usb

How To Make A Bootable Macos Installer

Other macOS installation options

Download Mac Os To Usb

By default, macOS Recovery installs the latest macOS that was previously installed on your Mac.* You can get other macOS versions using one of these methods:

  • On an Intel-based Mac, you can use Option-Command-R at startup to upgrade to the latest macOS that is compatible with your Mac. Exceptions:
    • If macOS Sierra 10.12.4 or later was never previously installed, you will receive the macOS that came with your Mac, or the closest version still available.
    • If your Mac has the Apple T2 Security Chip and you never installed a macOS update, you will receive the latest macOS that was installed on your Mac.
  • On an Intel-based Mac that previously used macOS Sierra 10.12.4 or later, you can use Shift-Option-Command-R at startup to install the macOS that came with your Mac, or the closest version still available.
  • Reinstall macOS from the App Store instead of using macOS Recovery. If you can't install the latest macOS, you might be able to install an earlier macOS.
  • Create a bootable installer, then use it to install macOS on your Mac or another Mac.

Mac Os On Usb Drive

* If you just had your Mac logic board replaced during a repair, macOS Recovery might offer only the latest macOS compatible with your Mac. If you erased your entire disk instead of just the startup volume on that disk, macOS Recovery might offer only the macOS that came with your Mac, or the closest version still available.