Here are the steps to boot Mac from the USB flash drive: Power on the system. Press and hold the Option (Alt) key on the keyboard when the computer starts. Select the USB drive as a startup disk when the option appears.
- How to Create Bootable USB on Mac. There are a few general guidelines that can help get your machine started which are mentioned above, regardless of the OS the user prefers. Here are the methods to create a bootable USB drive on Mac. Creating a Bootable USB Using Terminal. The terminal is the default gateway to the command line on a Mac.
- Plug your external drive into your Mac. Power up (or restart) your Mac. Press down on the Option key while the Mac boots.
- Boot your Mac from a USB drive. Having made your flash drive bootable, you can use it on many different devices to install macOS. Here’s how to install macOS from an OS X boot USB drive: 1. Connect the carrier to the Mac you want to install the OS on. Open the installation manager.
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.
![Drive Drive](https://i.ytimg.com/vi/8ejKoOL72jU/maxresdefault.jpg)
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If you’re still using a Mac OS X the time will come when your computer won’t boot, or a problem may arise where you can’t take control of the device, and booting from an OS X installation media will be required.
This is why it’s recommended that you make a Mac OS X bootable USB when your Mac is in working conditions. However, if you find yourself on a scenario where your device (iMac, MacBook Pro, Air, Mac Pro or Mini) is not responding and you happen to have a Windows 10 device, then you can still be able to make a USB bootable installation media for your Mac OS X to reinstall the operating system using the Recovery Assistant.
These instructions will also work for Windows users who are running Mac OS X on a virtual machine and need to upgrade to the latest version. For instance, to OS X Yosemite.
Requirements
Before you dive into this guide, you’ll need a few things:
- A broken Mac computer with Mac OS X.
- A trial copy of the TransMac software.
- One high quality USB flash drive with 16GB of storage.
- A copy of Apple’s macOS (DMG file).
Now that you have all the necessary ingredients, you’re ready to make a Mac OS X bootable USB using the DMG file of the operating system with the steps below.
Create Mac OS X bootable USB installation media
Before you can use TransMac, you first need to partition your USB flash drive with a GPT partition, as a normal MBR partition may not work. To do this, you’ll need to use the Diskpart command-line utility on Windows 10.
Setting up GPT partition
Mac Os Recovery Using Usb Boot Drive
Use these steps to set up a USB drive with a GPT partition:
- Open Start on Windows 10.
- Search for Command Prompt, right-click the top result and select the Run as Administrator option.
- Type the following command to open Diskpart and press Enter:
- Type the following command to determine the USB flash drive and press Enter:
- Type the following command to select the storage and press Enter:Quick tip: The
select disk 1
command as an example, but you have to replace 1 with the number of the flash drive you want to use. - Type the following commands to delete everything from the USB thumb drive and press Enter:
- Type the following command to convert the drive into a GPT partition and press Enter:
- Type the following command to select the new partition and press Enter:
After you complete the steps, the USB flash drive from MBR to GPT format, you can use the steps below to create a bootable USB installation media to install Mac OS X.
Create USB install media
Use these steps to create a bootable media to install Mac OS X:
- Download and install a copy of TransMac.Quick note: TransMac is a paid software, but it has a 15-day trial solution, that give us more than enough time to move the DMG files to the USB drive from Windows. (If you want to support the developer, you can purchase the full version.)
- Insert the USB drive that you’ll use to fix your installation of OS X. (Remember that all the data in the USB will be erased. Make sure you take off any important documents.)
- Right-click the TransMac software icon and Run as administrator. (You’ll be prompted to Enter Key or Run, because we’ll be using it once, click the Run option.)
- On the left pane, you’ll see all the Windows PC drives listed, right-click the USB drive that you’re intending to use to reinstall Apple’s OS X and select the Restore with Disk Image option.
- In the warning dialog box, click the Yes button.
- Use the Restore Disk Image to Drive dialog box to browse for the DMG file with the installation files for Mac OS X Yosemite in this case, and click the OK button to create a bootable USB of the operating system.Now, you’ll have to wait a long time. No kidding. It could take one or two hours to complete the process depending on your computer and other variables.
![Drive Drive](https://cdn.osxdaily.com/wp-content/uploads/2011/07/lion-install-boot-from-usb.jpg)
Mac Os Usb Boot Disk
Once your bootable USB installation media is ready, remove it and insert it into your Mac, power it on, holding down the Option key, and select the USB you just created to reinstall Mac OS X.
Mac Os Install Usb Boot Drive
If you’re having issues trying to create a bootable media, you can get a USB flash drive that comes with Mac OSX ready to install.