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.

Jan 01, 2014 I presume that you're talking about the OS X installer itself. The.app contains additional files (the.dmg is one of the files inside the.app). The easiest solution is to go to the App Store on a working system and download a full copy of the installer from there. How to Open a DMG File in Windows Martin Hendrikx Updated April 2, 2018, 10:29pm EDT Whether you are an avid Mac programmer using a Windows PC, or you just found a DMG file on your Windows machine, it can be useful to know what it is and how to open it. Jul 15, 2016  Create a new folder on Mac and copy.APP file to the new folder. Open Disk Utility File New Image Image from Folder. Choose the new folder. Specify the name of the DMG file and the path where the file should be created and click Save button. Oct 29, 2013 Some steps will take some time to execute as it copies the data from the app to the sparse-image in the temporary folder. If everything goes fine, the end step will create a file on your Desktop named “Mavericks.iso“. This image file is what you needed, you can use the Disk Utility to convert it to DMG file if needed.

Download macOS

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

  • macOS Catalina, macOS Mojave, and macOS High Sierra 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.
    To get the required 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.
  • macOS Sierra downloads as a disk image that contains a file named InstallOS.pkg. Open this file and follow the onscreen instructions. It installs an app named Install macOS Sierra into your Applications folder.
  • OS X El Capitan downloads as a disk image that contains a file named InstallMacOSX.pkg. Open this file and follow the onscreen instructions. It installs an app named Install OS X El Capitan into your Applications folder.

Osx Create Dmg From App Store

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:*
    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 commands for Sierra and 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

Osx create dmg from appointment

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:

Osx Create Dmg From Apparel

Catalina:

Mojave:

High Sierra:

Osx Create Dmg From App Free

Sierra:

Create Dmg Mac

El Capitan: