MST Transformation Files

MST files are used to transform the content of an MSI package. They are often used by administrators to customize the behavior of an existing MSI file. They use the MST files together with the original MSI package in their software distribution systems such as group policies.

You can also use MST files with wrapped executable installers. A common scenario is that you want to pass command line parameters to the wrapped installer. In order to do that you can create an MST file that adds the WRAPPED_ARGUMENTS property to the property table.

Tools such as Orca can be used to generate a MST file. The image below shows how you can add this property and insert extra command line arguments for the wrapped installer. In this example, we add a logging parameter for our test program built with Inno Setup.

After the MST is saved, we can test it from the command line.

msiexec /i setup_1.0.msi TRANSFORMS=mylog.mst

Remember to have your command line running as administrator if you want to run it silently with a /q. Otherwise, the elevation will most likely fail.