Final answer:
To undo all changes since the last commit when unmounting an image, use version control commands or system-specific commands to revert to the last committed state before unmounting.
Step-by-step explanation:
To undo all changes made since the last ones were committed when unmounting an image, you'll typically need to discard the changes before you unmount. This process may vary depending on the system or software you are using. In the context of version control, 'committing' is a term used to describe saving changes to the version control system. If you are using a system that tracks changes to an image, like a virtual machine or a container system, you might have to use specific commands to revert changes.
For example, if you are using Git for version control, you can undo changes in your working directory that are not yet committed by using the command:
this will revert all changes to the last committed state. If you're working with container systems like Docker, you can simply stop and remove the container, and start a new instance based on the committed image. It's always recommended to consult the documentation specific to the tools you are using to ensure you're following the correct procedure for discarding changes.