Make Usb Hard Drive Bootable Mac Os Xcompubrown

Getting ready to create the bootable USB drive. You will then be prompted for your user password (or, if you have a touchbar, to touch the fingerprint sensor). With authentication out of the way.

Make External Drive Bootable Mac
Make External Hard Drive Bootable Mac

Method 1: Using TransMac. Download TransMac’s latest version for Windows from this link. Connect your USB drive. Right Click on your USB drive option in TransMac and select Format Disk for Mac. After that, right-click the USB Drive and select Restore with Disk Image. Point to your Mac OS.dmg.
Use your USB drive right-click on it and select format disk format this will format the USB drive so that it can be used to store the Mac OS operating system. One thing you need took care of that the USB drive needs in GPT partition in order to work on a Mac computer otherwise it won’t boot.
The simplest way to create a boot USB drive is to download DiskMaker X and use it to create your drive. Generally, the latest version supports only the latest version of macOS; if you want to install something older than macOS High Sierra, check the list of older versions and download one that’s compatible with your chosen operating system.

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 12GB 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 download 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 downloads 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 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

Make External Drive Bootable Mac

Connect the USB flash drive or other volume that you're using for the bootable installer.
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 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:*

Make External Hard Drive Bootable Mac

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:

Press Return to enter 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 volume is erased.
After the volume is erased, you may see an alert that Terminal would like to access files on a removable volume. Click OK to allow the copy to proceed.
When Terminal says that it's done, 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

Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing.
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 labled Options.
Select the volume containing the bootable installer, then click Continue.
When the macOS installer opens, follow the onscreen instructions.

Intel processor

Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing.
Press and hold the Option (Alt) ⌥ key immediately after turning on or restarting your Mac.
Release the Option key when you see a dark screen showing your bootable volumes.
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 that the External Boot setting in Startup Security Utility is set to allow booting from external media.
Choose your language, if prompted.
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 the appropriate path in Terminal:

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

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.

You may need a bootable macOS Catalina USB drive to cleanly install the operating system or downgrade the macOS beta version. You can follow the steps here to create a bootable disk for any available version. However, since macOS Catalina is the current stable release, let me show you how to make a bootable installer drive.

Before You Begin:

Make sure you have a USB flash drive with at least 16 GB capacity
If there are files on it, copy it somewhere else as we will be completely erasing it
Your Mac should be compatible with macOS Catalina

How to Create a Bootable macOS Catalina Installer Drive

Download macOS Catalina from the Mac App Store. (You may download beta versions from Apple Public Beta page, or the developer page.)
Once the download completes, the macOS Installer will launch automatically. Close it.
Next, open Finder and click on Applications. Right-click on Install macOS Catalina. Select Show Package Contents.
Open the Contents folder.
Now, open the Resources folder. Keep this folder open.
Open Terminal using Spotlight Search.
In Terminal type the word sudo and then give a space.
From the window in step 5, drag createinstallmedia to the Terminal.
Next, type --volume and give space.
Connect the USB flash drive to your Mac
Launch Finder and click on Go from the top menu bar. Next, click on Go to Folder. Here type /Volumes and hit enter (or click Go).
Click on your Pen drive and drag it into the Terminal window.
Hit the enter/return key. Enter your Mac’s password when asked. (While typing password in Terminal, you won’t see stars or typing confirmation. But keep typing it and hit the enter key when done.)
Next, when prompted, type y and hit the enter/return key again.

Done!

The USB drive will be erased first, and then installer files will be copied to it. Erasing will be relatively quick. However, copying will take considerable time. Even if it is stuck at 0% or 10% for long, do not quit the Terminal window. The process is ongoing.

Signing off…

Note: If you have a Mac with T2 Security Chip (that is, Macs introduced in 2018 or later), first follow this guide to allow booting from external media.

After you create the bootable USB drive, the process to install it is simple. Make sure the USB drive is connected to the Mac. Next, click on the Apple logo from the top left and choose Restart. When you hear the startup sound or see the Apple logo, immediately press and hold the Option key. Select the bootable installer as the startup disk, and follow the instructions.

If you have issues, we have an extensive guide that addresses tips to fix when Mac Recovery Mode is not working.

The founder of iGeeksBlog, Dhvanesh, is an Apple aficionado, who cannot stand even a slight innuendo about Apple products. He dons the cap of editor-in-chief to make sure that articles match the quality standard before they are published.

https://www.igeeksblog.com/author/dhvanesh/
https://www.igeeksblog.com/author/dhvanesh/
https://www.igeeksblog.com/author/dhvanesh/
https://www.igeeksblog.com/author/dhvanesh/