The Scenario

One needs to retrieve a couple of files from a windows installer package (.MSI file).

One could install the MSI and find the files in the *Program Files* folder but there are problesm:

  • can take too long to perform the installation
  • it's desirable to avoid *polluting* the machine with unneeded software (files, registrykeys, etc.)

 

A built-in solution is available in Windows

Via the command line

C:\> msiexec /a <filename of the msi>

For Example:

C:\> msiexec /a foobar.msi

 

What does the /a do?

the /a option creates an *administrative install*.

In short: instead installing the application the setup UI will ask you where to dump all the files in the MSI package.

 

What is an administrative install?

The scenario for the /a was intended to run the application from from a network location. For example, all the desktops in some corporation would just get a couple of the application's files and start menu shortcuts, etc. but most files would be on some remote location (network file share). This kept the disk footprint of the application small for each desktop.

The /a option is the tool the admin uses to create that share.