What is the 'BaseSystem.dmg' File
Mac users might suddenly notice a prompt stating 'Opening BaseSystem.dmg.' The window could just flash on the screen and disappear immediately, giving the user no chance to read its message. Both the alert and the enigmatic BaseSystem.dmg file could leave Mac users confused and wondering whether their Mac system has been infected with a PUP (Potentially Unwanted Program) or even worse, a serious malware threat.
Luckily, in nearly all cases, the prompt proclaiming to be opening a basesystem.dmg file is legitimate. In fact, its appearance is usually triggered by the user performing a backup of the system via Time Machine. This built-in backup feature was introduced in Mac OS X 10.5 Leopard and has been tweaked and refined by Apple ever since. With the launch of macOS 11 Big Sur, Time Machine was revamped to include support for the company's proprietary APFS (Apple File System). After creating a backup, users are then capable of restoring the whole system or only select files.
However, it is entirely possible for another application to be responsible for the prompt concerning a BaseSystem.dmg file. One way to check if this is the case is to use Terminal to locate all files named 'BaseSystem.dmg' on the system.
- Open Terminal. You can do so via the icon available in Launchpad or by typing terminal in the search field and opening the top result. Users can also go to their Applications folder, then open Utilities, and double-click Terminal.
- In the terminal window type or paste the sudo find / -name BaseSystem.dmg -type f 2>/dev/null command.
- Inspect the list of results and see which apps have a BaseSystem.dmg file associated with them.
- If you deem any of the applications to be untrustworthy, you can then proceed to remove them from the system.