I am able to use the following commandline to install a MSI with the arguments I want
I am unable to get the commandline to work when I add an MST
I have tried a few different options like /T instead of Transforms. The PS1 is in the same folder as the MSI /MST. What is the proper way to install a MSI with an MST using Powershell?
So, I'm not an MsiExec expert by any stretch. It looks to me like you've got the syntax right - escaped the internal double quotes and all - although I can't validate whether or not the syntax would actually work.
If you just ran the Msiexec command in Cmd.exe, would it work? Have you had the .PS1 explicitly change to the folder (using CD command) where it and the MSI/MST are located?
Correct if I create a .CMD file, this command will work:
And you're having the PS1 explicitly change into the proper folder, to make sure it's the "working folder," when it runs?
Beyond that I'm afraid I don't have any suggestions for you - I'm not able to test this in my own VMs to see what I can get it to do.
I will suggest this: The PowerShell Community Extensions (PSCX) include a little command-line utility. You feed it your command, and it tells you how PowerShell is interpreting that and feeding it to Cmd.exe. That might help you see what's up.
You might also try not using Start-Process, if you don't have to. Try just running the command in PowerShell as-is. That'll help you see if it's PowerShell somehow flubbing the command, or if it's Start-Process that's doing so. If it's Start-Process, consider putting the command into a BAT file, and using Start-Process to run the BAT file. A lot of layers, but it's essentially what's happening under the hood anyway and it'd help minimize PowerShell's parsing snafus, if that's contributing to the problem.
You have to put commas between the arguments.
Take a look at the PowerShell Application Deployment Toolkit. It provides a function to install an MSI with support for Transforms: