Process execution using Popen

[scidam]

Rather opening just notepad++.exe, I'd like to open a new tab with "Language" select as C.

Ability to do this depends on how notepad++ is developed. If it allows execution via command line something like "notepad++.exe --default-language=C" (I use --default-language option as an example, I don't know anything about notepad++), then you can easily do what you want. If don't, the only way is to run notepad++ and then emulate some actions (move mouse, click on desired tab etc) to get desired result. This question doesn't related to Python and Subproces module in general, everything depends on what you want to get, and how programs are implemented (does they allow external control by design).