How to create a macOS Catalina bootable USB installer
If you want to clean install macOS Catalina on your Mac, or install it on a separate partition, you would likely need to use a bootable USB drive. Using the USB drive, you can boot your Mac, start system recovery and format your system before installing the operating system. Here is how you can easily create a macOS Catalina bootable usb drive, with just a few Terminal commands.
macOS Catalina Bootable USB Requirements
Before we begin, make sure that you have the following ready:
- A USB flash drive with at 16GB storage space.
- A downloaded copy of macOS Catalina installer.
- A Mac already updated to macOS Catalina.
Terminal command for bootable USB creation
Once you confirm that you have all the above, you can move to the next steps.
- Make sure that the macOS Catalina installer that you downloaded is not corrupt. Once confirmed, move it to the Applications folder on your Mac.
- Plugin the USB drive into your Mac. Go to Disk Utility and make sure to format it properly. Make sure that it does not have any important data as it will be completely wiped out during this process.
- Open the Terminal app on your Mac. You can do so by going to Applications or by typing Terminal in Spotlight search.
- In Terminal, enter the following command and press Return. Since this command requires sudo, it will ask for your Mac password.
sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/Catalina --nointeraction
- Once the process completes, your bootable macOS Catalina USB drive will be ready.
Booting from macOS Catalina USB drive
To use the newly created USB drive on a Mac, you will have to follow the below steps:
- Restart Mac with the USB drive plugged in.
- Press and hold the Option key when the Mac display turns on.
- You will see the Startup Manager appear. Use the arrow keys to select the USB drive and press Return.
You will be taken into macOS Recovery next. From here, you can install macOS Catalina, use Disk Utility to format your drives, or restore your Mac using Time Machine.
This bootable USB drive can be handy in many different scenarios. Sometimes a clean install is required if your Mac has too many software issues, you mess around with a lot of beta software, need to sell your Mac, or just need a fresh start. Apart from clean installation, the bootable drive can also be used for Recovery, installation on a secondary disk partition or installation on other Macs which might not have access to Internet. The same USB drive can also be used to upgrade a Mac to macOS Catalina, without losing any data.
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