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
And if your Mac is experiencing problems, a bootable installer drive makes a handy emergency disk. Macworld also has bootable-install-drive instructions for Mavericks (OS X 10.9), Mountain Lion. Go to your computer’s BIOS settings and confirm that the optical drive is listed first in the boot. CD/DVD drives are disappearing from computers, leaving USB storage as the only option when re-installing an operating system. The process is fairly painless and, if you have a bit of time and patience you can complete the task on a Mac.
Find the appropriate download link in the upgrade instructions for each macOS version:
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.
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.
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
- 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.
- Open Terminal, which is in the Utilities folder of your Applications folder.
- 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: - Press Return after typing the command.
- When prompted, type your administrator password and press Return again. Terminal doesn't show any characters as you type your password.
- 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. - 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: Apple keyboard image.
- Plug the bootable installer into a compatible Mac.
- 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. - Choose your language, if prompted.
- 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.
- 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:
At some point, you may find a need to boot your Mac from a disc or a drive other than the primary Mac OS X startup volume. Apple made it easy so all you need to know is just a simple keyboard command.
Apple explorer safari free download. Let’s say you need to use the Mac OS X installation disc that came with your computer to reformat the hard drive and put it back to factory settings. Or maybe you’re trying to boot from a USB flash drive that has a clean install of OS X on it for troubleshooting purposes. Perhaps you’ve got a cloned backup of your entire Mac on an external hard drive and you want to make sure it’s bootable. These are all potential reasons for booting to an external device, among many others.
There easiest way to boot to any device other than a Mac’s internal hard drive is to press and hold the Option key immediately after hearing the Mac startup chime. Continuing to hold this button down will bring up a menu where you can select a disc or drive to boot from. Use the keyboard arrows to choose your boot device, then press the Enter key. The computer will start up from the chosen volume, but bear in mind performance will likely be much slower than when you normally operate your Mac. This is especially true of USB flash drives.
![Apple Apple](https://cdn.mos.cms.futurecdn.net/cc44dcaa55c2bb7922975dd882eff9fa-1200-80.jpg)
Rather than hold the Option key, you could instead just press & hold the C key if you’re booting from a CD or DVD disc. This will bypass the selection menu and immediately start from the disc. It won’t work for USB and FireWire drives, though.
Apple Booting Video Animation
Booting to another volume using either of these methods is a one-time temporary change, so you don’t have to worry about altering any settings to reverse it. Your Mac will go back to booting to it’s primary startup disk next time you reboot.