Apple published a page, Create a bootable installer for OS X. “With OS X El Capitan, Yosemite, or Mavericks, you can use a USB flash drive or other removable media as a startup disk from which to install OS X.” – Basil Bourque Jul 6 '16 at 23:53. Obtain The macOS / OS X Disc Image Go to Macintosh HD Applications and locate the 'Install macOS / OS X version name here ' installer package (e.g. 'Install macOS High Sierra') or find your backup copy of it. Right/control click on the 'Install macOS / OS X' installer package and select 'Show Package Contents' from the contextual menu.

How To Obtain And Use A macOS Disc Image (for OS X 10.7 or later)

• You made a backup copy of the 'Install macOS / OS X' installer package before installing macOS / OS X - click here
• You are about to purchase, download and install macOS / OS X - click here
• You have purchased and downloaded macOS / OS X but have not installed it yet - click here
• You have already purchased, downloaded and installed macOS / OS X - click here
• You have already obtained the macOS / OS X disc image and want to know what to do with the macOS / OS X disc image

A bootable install volume of macOS 10.13 allows users to perform a variety of tasks including formatting and clean installs, updating multiple Macs from the same USB flash drive installer (and without re downloading), and to use as a troubleshooting boot drive should the need arise, amongst other benefits for advanced and more technical users. To gain access to Disk Utility you can either boot to the Mac OS X DVD or make another partition on the USB/Firewire drive (assuming it is large enough) with a copy of the OS X disc itself. Then you can boot to that partition to run Disk Utility and transfer the image from the other partition to the computer’s hard drive.

Obtain the macOS / OS X Installer - macOS / OS X Not Purchased Yet

1. Go to Macintosh HD > Applications > App Store.
2. Go to Store menu and Sign In if necessary (using the Apple ID you purchased OS X 10.7 or later with).
3. From the 'Store' menu now select 'Search' and search for 'macOS'.
4. Locate the latest version of macOS / OS X e.g. macOS 11 Big Sur.
5. Click the 'Buy' button
NOTE: If the buy button is not available e.g. it says 'Install', 'Download' or 'Purchased' you have already bought macOS / OS X
6. Purchase and download the macOS / OS X Install installer package to your hard disk (it may take a while as it is 4.3GB+ in size).
7. At the point where the macOS / OS X installer has downloaded it will automatically launch and ask you to continue.
8. Do not click Continue yet.
9. Quit the macOS / OS X installer (yes, quit it).
10. Now go to Obtain The macOS / OS X Disc Image section below

Obtain the macOS / OS X Installer - macOS / OS X Already Purchased

1. Go to Macintosh HD > Applications > App Store.
2. Go to Store menu and Sign In if necessary (using the Apple ID you purchased OS X 10.7 or later with).
3. Alt-click on the Purchases icon. This will show you a list of all software previously purchased. The 'macOS / OS X' item in the list should have an 'Install' or 'Download' button to the right of it.
NOTE: If the button is greyed out e.g. it says 'Installed' or 'Downloaded' go to the macOS / OS X Already Purchased And Installed section below
4. Click the install or download button for macOS / OS X which will download the macOS / OS X Install installer package to your hard disk (it may take a while as it is 4.3GB+ in size).
5. At the point where the macOS / OS X installer has downloaded it will automatically launch and ask you to continue.
6. Do not click Continue yet.
7. Quit the macOS / OS X installer (yes, quit it).
8. Now go to Obtain The macOS / OS X Disc Image section below

Obtain the macOS / OS X Installer - macOS / OS X Already Purchased And Installed

1. Go to Macintosh HD > Applications and check for an 'Install macOS / OS X' item - if it exists go to the Obtain The macOS / OS X Disc Image section below otherwise continue with these instructions.
NOTE: If you have an additional compatible Mac running Mac OS X 10.6.6 or later that does not have the version of macOS / OS X you want already installed on it you could use that to download the installer again otherwise you will need one of the following external storage devices before continuing with these instructions:
• USB, FireWire or Thunderbolt hard disk
• USB stick
• SDXC card (if your Mac supports it e.g. recent MacBook Pro or Mac mini)
NOTE: The external storage device must be at least 8GB in size and erased/empty/formatted as a GUID Partition before use.
2. Restart your computer using the (Internet) Recovery mode
3. When the macOS / OS X Utilities window appears select the Install macOS / OS X option
4. Choose your external storage device as the destination
5. Let the installation start and watch the installation process carefully (it may take a while as it is 4.3GB+ in size)
6. When the Mac automatically restarts there will be a black screen for a moment - at this point unplug/eject/disconnect the external storage device
7. The Mac may stall for moment but then should boot normally to your desktop or login screen
8. Reattach the external storage device
9. There should be a folder on it called 'macOS / OS X Install Data' that contains a disk image file called 'InstallESD.dmg' - if this is missing, then you probably waited too long to unplug the drive. Go back and start this section again
10. Copy the 'InstallESD.dmg' file to your desktop or preferably to another disk/storage device or even burn it to a DVD so that you have a backup of it.
11. Now choose what you want to do with the macOS / OS X disc image

Obtain The macOS / OS X Disc Image

1. Go to Macintosh HD > Applications and locate the 'Install macOS / OS X version name here' installer package (e.g. 'Install macOS High Sierra') or find your backup copy of it.
2. Right/control click on the 'Install macOS / OS X' installer package and select 'Show Package Contents' from the contextual menu.
3. Navigate to Contents > SharedSupport and locate the 'InstallESD.dmg' file.
4. Copy the 'InstallESD.dmg' file to your desktop or preferably to another disk/storage device or even burn it to a DVD so that you have a backup of it.
5. Close all the windows.
6. You can now use the macOS / OS X disc image (InstallESD.dmg) to:
• Create an External Installation Device.
• Create an Emergency Boot Drive for macOS / OS X / Mac OS X you can use it to boot your computer and repair your hard disk and/or reinstall macOS / OS X / Mac OS X.
• Create an Install DVD (see instructions below).

How To Create An Install DVD From The macOS / OS X Disc Image

1. Obtain the macOS / OS X Disc Image (see instructions above).
2. Go to Macintosh HD > Applications > Utilities > Disk Utility.
3. Click on the 'Burn' button at the top of the Disk Utility window.
4. Navigate to the macOS / OS X disc image ('InstallESD.dmg' file)
5. Select the disc image.
6. Click the 'Burn' button.
7. Insert the blank/unused DVD-R or DVD+R disc.
8. Follow the on screen instructions.

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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.

What you need to create a bootable installer

• A USB flash drive or other secondary volume, formatted as Mac OS Extended, with at least 12 GB of available storage
• A downloaded installer for macOS Big Sur, Catalina, Mojave, High Sierra or El Capitan

Download macOS

• Download: macOS Big Sur, macOS Catalina, macOS Mojave or macOS High Sierra
  These will be downloaded to your Applications folder as an app named Install macOS [version name]. If the installer opens after downloading, quit it without continuing installation. 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.
• Download: OS X El Capitan
  This will be downloaded as a disk image named InstallMacOSX.dmg. On a Mac that is compatible with El Capitan, open the disk image and run the installer within, named InstallMacOSX.pkg. It will install 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.
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 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.

Big Sur:*

Catalina:*

Mojave:*

High Sierra:*

El Capitan:

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

After typing the command:

1. Press Return to enter the command.
2. When prompted, type your administrator password and press Return again. Terminal doesn't show any characters as you type your password.
3. When prompted, type Y to confirm that you want to erase the volume, then press Return. Terminal shows the progress as the volume is erased.
4. After the volume has been erased, you may see an alert stating that Terminal would like to access files on a removable volume. Click OK to allow the copy to proceed.
5. When Terminal says that it's been completed, the volume will have the same name as the installer you downloaded, such as Install macOS Big Sur. You can now quit Terminal and eject the volume.
   

Use the bootable installer

Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:

Apple silicon

1. Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing.
2. Turn on your Mac and continue to hold the power button until you see the startup options window, which shows your bootable volumes and a gear icon labelled Options.
3. Select the volume containing the bootable installer, then click Continue.
4. When the macOS installer opens, follow the onscreen instructions.

Intel processor

1. Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing.
2. Press and hold the Option (Alt) ⌥ key immediately after turning on or restarting your Mac.
3. Release the Option key when you see a dark screen showing your bootable volumes.
4. Select the volume containing the bootable installer. Then click the up arrow or press Return.
   If you can't start up from the bootable installer, make sure the External Boot setting in Startup Security Utility is set to allow booting from external media.
5. Choose your language, if prompted.
6. Select Install macOS (or Install OS X) from the Utilities window, then click Continue and follow the onscreen instructions.

Learn more

Mac Os Disk Image Download

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

Mac Os X Bootable Disk Image Download Torrent

• Big Sur: /Applications/Install macOS Big Sur.app/Contents/Resources/createinstallmedia
• Catalina: /Applications/Install macOS Catalina.app/Contents/Resources/createinstallmedia
• Mojave: /Applications/Install macOS Mojave.app/Contents/Resources/createinstallmedia
• High Sierra: /Applications/Install macOS High Sierra.app/Contents/Resources/createinstallmedia
• El Capitan: /Applications/Install OS X El Capitan.app/Contents/Resources/createinstallmedia

Mac Os X Bootable Disk Image Download Iso

A bootable installer doesn't download macOS from the internet, but it does require an internet connection to get firmware and other information specific to the Mac model.