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.

Download macOS

Find the appropriate download link in the upgrade instructions for each macOS version:

With the SanDisk Ultra Dual Drive USB Type-C flash drive, file transfers between your Mac and other devices just got better. It has a USB Type-C connector at one end and traditional USB one at the. What is a flash drive? A Flash Drive is a small self-powered drive that connects to a computer directly through a USB port. It’s both Mac and PC compatible, so you can use it to transfer files between both Macs and PCs. Flash drives can hold any type of data, making them an ideal way to back up your files.

macOS Catalina, macOS Mojave, ormacOS High Sierra
Installers for each of these macOS versions download directly to your Applications folder as an app named Install macOS Catalina, Install macOS Mojave, or Install macOS High Sierra. If the installer opens after downloading, quit it without continuing installation. Important: 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.

OS X El Capitan
El Capitan downloads as a disk image. 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

Flash Drives For Macbook Pro

1. Connect the USB flash drive or other volume that you're using for the bootable installer. Make sure that it has at least 12GB of available storage and is formatted as Mac OS Extended.
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 still 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.
   Catalina:*
   Mojave:*
   
   High Sierra:*
   El Capitan:
   
4. Press Return after typing the command.
5. When prompted, type your administrator password and press Return again. Terminal doesn't show any characters as you type your password.
6. When prompted, type Y to confirm that you want to erase the volume, then press Return. Terminal shows the progress as the bootable installer is created.
7. When Terminal says that it's done, the volume will have the same name as the installer you downloaded, such as Install macOS Catalina. You can now quit Terminal and eject the volume.

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

Use the bootable installer

After creating the bootable installer, follow these steps to use it:

1. Plug the bootable installer into a compatible Mac.
2. Use Startup Manager or Startup Disk preferences to select the bootable installer as the startup disk, then start up from it. Your Mac will start up to macOS Recovery.
   Learn about selecting a startup disk, including what to do if your Mac doesn't start up from it.
3. Choose your language, if prompted.
4. A bootable installer doesn't download macOS from the Internet, but it does require the Internet to get information specific to your Mac model, such as firmware updates. If you need to connect to a Wi-Fi network, use the Wi-Fi menu in the menu bar.
5. Select Install macOS (or Install OS X) from the Utilities window, then click Continue and follow the onscreen instructions.

Learn more

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

Catalina:

Mojave:

High Sierra:

El Capitan:

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What is a flash drive?

A flash drive is a small, removable hard drive that plugs in to a USBport on your computer. You can purchase a flash drive for less than $20 at just about any retail store with an electronics department, and even at some grocery stores and pharmacies. Flash drives are a convenient way to bring your files with you and open them on a different computer. You could also use a flash drive to back up important documents and other files. In this lesson, we'll show you how to use a flash drive with your computer.

To connect a flash drive:

1. Insert the flash drive into a USBport on your computer. You should find a USB port on the front, back, or side of your computer (the location may vary depending on whether you have a desktop or laptop).
2. Open Finder and locate and select the flash drive from the Sidebar on the left side of the window. Note that the name of the flash drive may vary. You may also see the flash drive on the desktop. If so, double-click it to open the flash drive in a new Finder window.

If you don't see the flash drive on the desktop, go to Finder > Preferences (you may have to click the desktop first to switch to Finder). Next, make sure the External disks option is checked on the General tab.

How to work with a flash drive:

Once you've connected a flash drive, you can work with it just like any other folder on your computer, including moving and deleting files.

1. If you want to copy a file from your computer to the flash drive, click and drag the file from your computer to this window.
2. The file will be duplicated, and the new version will be saved to the flash drive. The original version of the file will still be saved to your computer.
3. If you want to copy a file from your flash drive to your computer, click and drag the file from the window to your computer.
4. If you want to remove a file from your flash drive, click and drag the file to the Trash, then click and hold the Trash icon and select Empty Trash to permanently delete the file.

Flash Drives For Mac Computers

To safely remove a flash drive:

Flash Drives For Mac Book Air

When you're done using a flash drive, don't remove it from the USB port just yet! You'll need to make sure to disconnect it properly to avoid damaging files on the drive.

Flash Drives For Mac Os X

1. In Finder, click the Eject button next to the flash drive. You can also right-click the flash drive and select Eject.
2. You can now safely remove the flash drive from the USB port.

Flash Drives For Macintosh

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