I have long advised to create a bootable installation unit, on an external hard drive, a pen drive or a USB stick, for the version of macOS running on your Mac. It is great for system installation. operating on multiple Macs, because you do not need to download the ~ 6GB installer on each computer and act as a convenient emergency disk in case of Mac problems.
Here is the version of this year's guide to my annual guide. The procedure has changed slightly this year due to a change in Apple createinstallmedia tool.
How to get the Mojave installer
You can get the latest version of the Mojave installer from the Mac App Store. (Developers can get the current version of Mojave through the developer download site, scroll down to "Release Software".)
What you need
To create a bootable Mojave installer, simply install the aforementioned drive and a drive with Mac formatting (a hard drive, solid state drive [SSD], pen drive or USB stick) that is big enough to hold the installer and all of its data: an 8 GB pen drive is perfect.
The installation drive must be formatted as a Mac OS Extended (Journaled) volume with a GUID partition table. Macworld has a nice tutorial that explains how to properly format the unit.
Your macOS user account must also have administrator privileges.
Important: When you download the Mojave installer from the Mac App Store, it will be saved in the main Applications folder (/ Applications); it must be in that position for the following procedure to work. However, if you to run for example, to install the operating system from that location, the installer will automatically delete it after installation is complete. Therefore, if you plan to run the installer before starting the bootable installation drive, first make a copy of the installer in another folder or on another drive so you have a secure copy; before creating the bootable installer, move the copy back to the Applications folder. (If you have read this paragraph too late and the installer has already been deleted after an installation, you only have to re-download Mojave from the Mac App Store, via the Purchasing tab, before you can create the installation unit bootable.)
The easiest way is to create installmedia
Starting from Mavericks, hidden within the OS X installer is called a Unix program createinstallmediaprovided by Apple specifically for the creation of a bootable installation unit. Using it requires the use of Terminal, but it works well, it's official and the procedure is quite simple: if you can copy and paste, you can do it.
The only disadvantage of createinstallmedia is that it does not work with OS X 10.6 Snow Leopard, requires OS X 10.7 Lion or later. But I suspect that in 2018, virtually everyone who installs MacOS 10.14 Mojave will have access to a Mac running 10.7 or later.
- Connect an 8GB (or larger) formatted drive to your Mac and rename the drive
Without title. (The Terminal command I provide here assumes that the unit is called Untitled.) Also, make sure the Mojave installer (or at least one of its copies), called Install macOS Mojave.app, is in its default location in the main Applications folder (/ Applications).
- Select the text of the Terminal command below and copy it:
- Launch Terminal (in / Applications / Utilities).
- Warning: this step will delete the drive or destination partition, so make sure it does not contain valuable data. Paste the copied command into the terminal, making sure there are no double dashes (
-) have been replaced by the following indents (-); press Enter.
- Type the password of the administrator level account when prompted, and then press Enter.
sudo / Applications / Install macOS Mojave.app/Contents/Resources/createinstallmedia --volume / Volumes / Untitled --nointeraction
The Terminal window shows the progress of createinstallmedia as a text representation of a progress bar: Cancellation disc: 0% … 10 percent … 20 percent … and so on. In addition, a list of program activities is displayed as soon as they occur: Copy to disk … Make the disk bootable … Copying startup files …. On a recent Mac with a fast destination drive, the procedure should take no more than 5 minutes, although it can take up to 20 or 30 minutes on a previous Mac or a very slow drive. The process is finished once you see Install the now available support in / Volumes / Install macOS Mojave, as shown in the screenshot above. If you wish, you can then rename the unit (in the Finder) from its default name of Install macOS Mojave.
Starting from the installation unit
You can start any Mac compatible with Mojave from your new installer. First, connect the drive to your Mac. So, if your Mac is already running in macOS, choose the installation drive in the Startup Disk pane of System Preferences and reboot; or, if your Mac is currently turned off, hold down the Option key to start up and choose the installer when MacOS's Startup Manager is displayed.
Once started from the installation unit, you can perform any task available from the special restore and restore features of the macOS installer. In fact, you'll see the same MacOS Utilities screen that you get when you run MacOS Recovery, but unlike the recovery mode, your bootable installer includes full installer.
A note on the macOS updates
In the coming months and years, Apple will release MacOS Mojave updates that provide security patches, bug fixes and even new features. However, any Mojave installer you create will install the version of Mojave available when the installer is downloaded. This means that if you use a unit that you now create to install Mojave on a Mac in six months, you will have to manually update that Mac with all the Mojave updates released in the meantime.
Unfortunately, it is not possible to easily update the installation unit to install the latest version. If you want to create a bootable drive that directly installs the latest Mojave version, you need to download the latest version of the Mojave installation app from the Mac App Store, then repeat the steps above using the new app installation.
Comments or questions? @danfrakes on Twitter or send me an email to siteemail in this domain.