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How to run an exe file with arguments in an UWP application?
For your scenario, the quick way to accomplish the scenario is to have the UWP write the command string to the local app data/settings, which is shared between the two processes. So the full-trust process can then pick up the command string after its been launched from there.
For more detail you could refer stefan's blog UWP with Desktop Extension – Part 2 and it contains code sample that you could refer.
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