Create a macOS installer USB drive

A bootable drive to install or repair several Macs.

1. Download the macOS installer from the Mac App Store or Apple's support page (see the ISO tab). It lands in Applications.
2. Plug in a drive of at least 16 GB and format it with Disk Utility as "Mac OS Extended (Journaled)", named MyVolume.
3. In Terminal, run createinstallmedia (adapt the application name to the version you downloaded):

   sudo /Applications/Install\ macOS\ Tahoe.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

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4. Type Y to confirm and wait until it finishes.
5. To boot from it: Apple silicon Mac → hold the power button; Intel Mac → hold Option (⌥) at startup.