How to merge xml app.config files outside of the build process

Question

I would like to use app.config files for settings, but I don't want to have to select different build configurations to select which settings to use, I would rather everything build in release and then just the app.config file be different when the application is deployed.

What is a good way to merge two xml files together so that I can deploy the correct settings to the correct environment? I have found several solutions that are based on selecting different build configurations and the transform happens at build time, but I want the transform to just be from a command line utility that my deploy script can run

Answer 1

At my company, we use the Web Config Transformation Runner, available on GitHub. It may be invoked directly from the command line, a bit like this:

D:\Utils\WebConfigTransformRunner.exe App.config App.production.config App.config

We've incorporated this into a larger packaging and deployment process to handle deploying to our various environments.