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.
Aug 08, 2011 Built right into OS X, OS X Recovery lets you repair disks or reinstall OS X without the need for a physical disc. The OS X Recovery Disk Assistant lets you create OS X Recovery on an external drive that has all of the same capabilities as the built-in OS X Recovery: reinstall Lion or Mountain Lion, repair the disk using Disk Utility, restore from a Time Machine backup, or browse the web with. May 05, 2015 The Recovery disk is the best friend you never knew you had. Tucked away in a 650Mb partition on the system drive is a set of tools you can use to fix and restore your drive should it crap out on you. It’s not an installer. It’s a fixer, a toolkit. It props up your broken machine long enough so you can reinstall or restore your system. Here is how to repair Mac disk and recover Mac with OS X Recovery Disk: To put your Mac into Recovery Mode, restart your machine and hold down the 'Command + R' keys on your keyboard simultaneously.Continue to do this until the Apple logo appears. When your Mac has started up, the OS X Utilities window will appear and prompt you to choose one of the four options listed above.
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.
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.
MyVolume in these commands with the name of your volume.Y to confirm that you want to erase the volume, then press Return. Terminal shows the progress as the bootable installer is created. * 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.Xcode 8.2.1 for el capitan.
After creating the bootable installer, follow these steps to use it:
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: