Mistakes with syntax can lead to permanent data loss, or the erasure and formatting of the wrong disk, so proceed at your own risk. This process requires using the command line, if you are not comfortable using the Terminal than it is better to avoid this process. How to Make a Bootable macOS Catalina 10.15 Beta USB Installer Drive The Mac will also need to be online so that it can download the MacOS Catalina installer, if that hasn’t already be accomplished. Knowledge and understanding of the command line and Terminal.A complete “Install macOS Catalina.app” installer application residing in the /Applications/ folder on the Mac (you can download full macOS installers from Terminal with these instructions on newer MacOS releases, otherwise use the MacOS Catalina download link via App Store).USB flash drive (16GB or larger) – this will become the boot install driver for MacOS Catalina, it will be formatted so any data on this drive will be erased to become the boot installer.The following prerequisites are necessary to make a bootable installer drive for macOS Catalina: Requirements to Create a Bootable macOS Catalina USB Install Drive We’ll walk through how to create a boot USB install drive for MacOS Catalina 10.15. Bootable USB installers offer an easy way to upgrade multiple Macs to macOS Catalina, to perform clean installs of MacOS Catalina, to perform maintenance from a boot disk like formatting disks, modifying disk partitions, and performing restorations, and much more.

Bootdisk utility tutorial