Under critical circumstances, your installation of macOS could be damaged by a disk drive failure or by a third-party application which used administrative permissions in such a way that the operating system is no longer starting correctly or does not start at all. When you cannot work with the operating system any longer, utility programs like TinkerTool System also can no longer be of any help to resolve this problem.
Similarly, macOS might still be running, but an important system component which is needed by TinkerTool System could be damaged. Even if TinkerTool System is capable of repairing this failing component during normal operation, this will not help in this particular case, because you might not be able to launch TinkerTool System due to the damage.
However, TinkerTool System offers a solution which can help you even in those two critical cases. The application contains a mini version which can be launched in the special recovery operating system of macOS. The recovery operating system is installed as an addition to each standard operating system into a special read-only volume. It should always launch, even in emergency situations. The small standalone version of TinkerTool System is called TinkerTool System for Recovery Mode, or abbreviated ttsfrm.
Note that you should inform yourself beforehand, before a critical problem occurs, how to launch TinkerTool System in Recovery Mode. You will then be prepared for an emergency. The respective instructions can be printed. They can be different for each computer.
To print the instructions how to launch TinkerTool System for Recovery Mode, perform the following steps:
TinkerTool System will automatically adjust the output to the paper size of your printer.
The individual launch command for your computer is shown at the end of the instructions. The command is different depending on the location of the program and the names of your volumes, folders, and application. It could be, for example:
"/Volumes/Macintosh HD - Data/Applications/TinkerTool System.app/
Contents/SharedSupport/ttsfrm.app/Contents/MacOS/ttsfrm"
The actual call that must be typed as one single line into the Terminal window to launch the application, can be reconstructed as follows:
This means the pattern of the call is
"/Volumes/<volume>/<folder1></.../><folderX>/<program>.app/
Contents/SharedSupport/ttsfrm.app/Contents/MacOS/ttsfrm"
where all parts within angular brackets must be replaced by the actual names that are established on your computer. Don’t omit the quotation marks and don’t replace them by typographical variants. Press the return key only at the end, even if the command above is written in multiple lines for reasons of space. To make it easier for you to recognize spaces, they are marked with the special character ␣ in the instructions.
If you have multiple disk volumes on your Mac or even multiple operating systems are installed, there will be restrictions which volumes will later be accessible in Recovery Mode and which operating system can be repaired. The following basic rule applies:
TinkerTool System for Recovery Mode only works on the volume group and its associated operating system where the application itself has been stored.
This results in the following consequences:
A volume group for macOS consists of the system volume, its associated snapshot volume, and its data volume. You can review the details of this grouping via the pane APFS.
TinkerTool System for Recovery Mode can only be used after the recovery operating system of macOS has been started. Detailed information on this topic can be found in the chapter Working in macOS Recovery Mode.
Older variants of TinkerTool System had been shipped with a different type of emergency tool which was designed for the Single User Mode of macOS. This program had to be installed expressly in a separate step. Apple no longer supports Single User Mode of macOS officially and many Macs are now pre-configured by default to prohibit Single User Mode for security reasons. This has made the old version obsolete, so it should be removed. TinkerTool System detects automatically whether an outdated version of the previous software is available in the running operating system. It will show this at the bottom of the Emergency Tool pane. In this case, simply click the button Remove legacy tool and follow the application’s instructions to clean your Mac.