As of summer 2011, Apple distributes operating systems only as downloads of installer Apps from the Mac App Store, or together with new Macs. This means there is no longer a tangible medium holding a copy of the operating system which could be used in case of emergency when the running copy of the OS on your computer was damaged or erased. There is only a small mini operating system for emergency cases stored in the recovery partition, which is usually installed for each operating system partition on your Mac and for each Time Machine destination disk. The recovery system allows you to download a copy of the full operating system from the Internet again when you have lost it. Depending on the speed of your Internet line, a full download may take more than 4 hours, however. In cases where all disk drives of your Mac have been erased or have become unusable, you can also start the recovery system by a NetBoot feature, so the emergency system is directly loaded from an Apple-provided Internet server.
All these emergency procedures won’t help if you need to install a new operating system on a Mac which has no Internet connection, or which should not have such a connection for security reasons. For such cases, all Mac operating systems as of OS X 10.9 or later support a feature to create standalone install media. Such a medium behaves like a classic operating system DVD: The computer can be started from it, and you can install a full copy of the operating system without the need for an Internet connection. The medium can also fully replace a recovery system: It contains all components of the recovery OS, so you can use Disk Utility, Terminal, or the “complete restore” feature of Time Machine for maintenance purposes if the main OS is no longer working correctly.
TinkerTool System can guide you through the process of creating macOS install media. A bootable installer can be created by a few mouse clicks.
You need additional software and hardware to create macOS install media. The following items are required:
A few operating system installers downloaded from the App Store may be incomplete. In such a case, the installer app is a “stub” only which does not contain the actual operating system, but only information how to internally download the missing parts from Apple in case they are needed. You can recognize such an app by its size of only between 20 and 30 MB. Unfortunately, it won’t be possible to create install media with such an incomplete installer. TinkerTool System will correctly detect this, giving you a respective warning in this case. The App Store may decide per customer and per OS version when to offer a complete or an incomplete operating system installer package.
TinkerTool System 6 does not support installer applications for macOS 12 or later.
If macOS or TinkerTool System have problems detecting an external storage device which should be used to create install media, erase the device first, creating an empty HFS+ file system:
After the device has been erased, macOS and TinkerTool System will accept it as destination medium.
This feature is not available on macOS Mojave.
If you have problems getting the right installer from the App Store, you can instruct macOS to automatically find a specific installer and to perform the download:
We cannot predict which installer versions Apple will offer in your region and for your specific Mac. The available versions may change any minute without further notice.
You will see in the download sheet whether Apple is indeed offering an installer with the specified version number to you. Depending on the speed of your Internet line, the download may take several hours. After the download has been completed successfully, you will find the installer in the main Applications folder. If you stop the download procedure, macOS may decide to continue the operation in the background. TinkerTool System has no influence on this.
To create the standalone installation disk, perform the following steps:
Warning: The volume selected as install medium will be erased completely. You should not assume that other volumes or partitions on the same disk remain untouched. In the worst case, they could be removed as well if Apple’s installer has to make changes to the partitioning scheme. To avoid misunderstandings, it is recommended to use install media that contains one single volume only.
If TinkerTool System doesn’t list a device you like to use, please read the instructions in the previous section.
Creating the installer disk is not directly managed by TinkerTool System, but by the installer App you downloaded from the App Store. For this reason, the procedure might slightly vary depending on what operating system version you are using.
As part of the creation process, macOS might open parts of the created system in a new Finder window which might appear at the end of the procedure. The window can be used to check successful creation of the disk. You can safely close the window and eject the disk.