Launch application with RS-232 message

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Hi i am using a PC104 with Linux and i need to control it with a controller that is connected via RS-232 or USB port. I need to launch one or more application some specific message come through RS-232 port. Is that doable? If yes how? I am beginner with C++ on Linux so i don't really know specif libraries. If possible i would like to use pure C and not C++.

Thank you!