Based on the ISO-9660 standard format, an ISO image file (one with an '.iso' extension) is a type of disc image file used to replicate the contents of an optical disc, such as a CD. ISO files are CD/DVD disk image files contain an exact duplicate (with the same folders, files, and properties) of the data stored on a disk even when the user does.

  1. In this video the tutor shows how to make an ISO image file on a Mac. He shows what the requirements are to get started. He points to the disk utility program from where he points to the option where we can open a disk image from a folder. Now he selects the folder to which he wants to save the image. Now he guides us through the rest of the settings on how to prepare the image.
  2. You can create an empty disk image, add data to it, then use it to create disks, CDs, or DVDs. In the Disk Utility app on your Mac, choose File New Image Blank Image. Enter a filename for the disk image, add tags if necessary, then choose where to save it.

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:

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

  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.
Mac

* 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

CreateCreate

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.

Create Iso File Mac Os X

Learn more

Create Iso Mac Os

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:

Create iso file from folder

High Sierra:

Creating Iso Files For Mac

El Capitan:

⇐ ⇐ Mediaget For Mac Download
⇒ ⇒ Aggregate Device For Mac