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How to make a bootable macOS USB drive fast, with no special software
Short answer: you do not need any special program to make a bootable macOS USB drive. Download the macOS installer from the App Store and run the createinstallmedia command that comes inside Apple's own installer from Terminal. In the video I do it with OS X El Capitan and rename the flash drive to "123" so the command is easy to type without mistakes.
What you need
- A working Apple computer (Mac).
- A USB flash drive. Everything on it will be erased, so back it up first.
- The macOS installer downloaded from the App Store (El Capitan in the video; the method works for other versions).
- Apple's official guide as a reference: Create a bootable installer for macOS.
The advantage of this method is that it is legal and official: no ISO files from unknown sites and no third-party apps.
Step 1: Rename the flash drive to something simple
Open Finder, right-click the flash drive (or two-finger tap on the trackpad or Magic Mouse) and choose Rename. I recommend a short name like 123. You will type that name inside the command later, and a simple name avoids typos and spaces that break the path.
Step 2: Download the macOS installer
Go to the App Store, find the version of macOS you want and download it. When it finishes, the installer sits in your Applications folder (for example "Install OS X El Capitan"). You do not need to open it.
Step 3: Open Terminal and become root
Click the Spotlight magnifying glass at the top right, type Terminal and press Enter. In the video I type sudo -i, press Enter and enter the Mac's password. You need to see the word root on the command line; if it is not there, the next command will not work. Apple's guide puts sudo in front of the command; if that does not work for you, log in with sudo -i first as shown in the video.
Step 4: Type the createinstallmedia command
The command has three parts: the path to createinstallmedia inside the installer, the volume of the flash drive, and the path of the application. For El Capitan and a drive named 123 it looks like this:
/Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/123/ --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app/
- Type everything exactly the same, respecting capital letters, slashes and the backslash before every space.
- Use the Tab key to autocomplete: pressing Tab twice after
/Volumes/shows every external drive connected, including yours (123). - After
--volumegoes the flash drive path; after--applicationpath, the installer path.
Step 5: If you get an error, check what you typed
If you press Enter and see an error message, it is almost always a typo. That is exactly what happens in the video: I delete the wrong part, fix it, press Enter again and the command works.
Step 6: Confirm the erase and wait
The command warns that it will erase the flash drive. If you already backed it up, type Y and press Enter. It first erases the disk and then copies the installer. Depending on the computer and the flash drive it can take from about 15 minutes (with a fast drive) up to an hour. When it finishes, the bootable USB is ready to reinstall the system from scratch.
Frequently asked questions
Do I need to download an ISO file or a program?
No. Everything is done with the official installer from the App Store and the createinstallmedia command that comes inside it, from Terminal.
Why rename the flash drive to 123?
Because the drive name is part of the command (/Volumes/123/). A short name without spaces avoids typing mistakes.
Will it erase what is on my flash drive?
Yes. The process erases everything on the flash drive, so back it up before confirming with Y.
How long does it take?
It depends on the computer and the flash drive: from about 15 minutes with a fast drive up to half an hour or an hour.
What if the command gives an error?
Check that everything is typed exactly right, including the volume name, and that you are root (sudo -i). Fix the mistake and press Enter again.