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how to create a bootable macOS installer

If you are preparing to install macOS on multiple computers, one of the things that can make your life simpler (and the waiting shorter) is a bootable USB installer.

The idea of the installer is that you only need to download the macOS Installer.app from the App Store once. Usually, when you run the installer after downloading it, it’ll delete itself and you have to go through the whole download process again on each machine or disk that you want to install macOS onto. By making a bootable USB drive, you simply plug the drive in to your mac, launch the installer app and tell it where to install the OS. You can repeat this as many times as you like as the installer will remain safe on your USB.

There are various ways to make a bootable USB installer, but they all involve the same process:

1. Download the macOS Installer from the App Store.
2. Run the createinstallmedia command from the Terminal, an AppleScript or a helper app.
3. Reboot your mac, choosing the newly created USB as the startup disk.
4. Run the installer.app from the USB.

Step 2 is where the fun is. The createinstallmedia command can be tricky to get right, particularly if you’re not familiar with working on the command line. For those of you that are, follow Apple’s instructions here.

For a little more convenience, I wrapped all that inside an AppleScript which will first ask you for the location of the installer, then ask you to choose the USB target.

For maximum convenience, I also wrote a free little Swift app I’ve dubbed ‘Boot Buddy‘ (cos “Create bootable macOS Installer Drive.app” just didn’t quite have the right ring to it..!) that will present the whole thing in a neat little user interface. Three clicks, more or less, and you’re done.

Boot Buddy doesn’t require an admin password to install, but you do need to provide an admin password to actually create the bootable installer as the createinstallmedia process has to be run as root. Boot Buddy doesn’t see or use this in any way whatsoever other than to start the createinstallmedia process or to cancel it (if you choose to do so); authorisation is handed off to macOS to take care of.

Boot Buddy requires macOS 10.11 or higher and can create bootable USBs from Mavericks, Yosemite, El Capitan, Sierra and High Sierra installer apps.











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how to back up your Mac – the best way!





iCloud? Time Machine? Noooo……! We’re talking about the best way to backup your precious data, not the most convenient way…

What’s wrong with using the cloud? The fact that you need an internet connection, a password to be accepted, to act in accordance with the T&C of your cloud provider, the fact that someone – government, corporation, hacker – could interfere with your data, lose it or just add unwanted stuff to it. Also, if you want to backup your whole system then the various free storage offers are not going to be big enough to do the job, and you’re going to end up paying a lot more than if you backup your system properly.

How about Time Machine? Yes, it’s simple and convenient and pretty much automatic, but its not secure. TM has three major problems. First, it doesn’t allow proper archiving so anything you delete from your HDD will eventually get deleted from TM. Second, it doesn’t tell you what it’s doing before it does it, meaning you are at the mercy of its automated decisions. Third, it’s not bootable. If your whole system crashes or your HDD just fails, Time Machine won’t help you. You’ll have to restore the system or replace the HDD before you can use your machine again.

But there is a much better way, and aside from you providing the hardware (a couple of external hard disks), one that’s also free. The most secure system is to run an hourly or daily scheduled cloner on one disk, and a weekly cloner on the other. You can use SuperDuper or, my own favourite, Carbon Copy Cloner.

If you want to read up on and understand the various backup options and what they entail, you can’t do better than to read this superb post by Apple Discussions member ds store.

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