So many people saying this is "too much magic". Whatever, I'm into it. The idea of commands being functions that can just pass their output to other functions is intuitive, and passing arguments as, well, arguments is as well.
It might not be pythonic, it might be a crime against Guido and everything he represents, but it's pretty awesome.
I have the feeling you misunderstood the problem with magic. In fact, having a function calling shell command is ok. The problem is to know, from reading the code, where it comes from. In python there is this idea of transparency, the determinism, which is with it feels enlightening, like in the docs cartoon. Anything obscuring that is said to be unpythonic.
It might not be pythonic, it might be a crime against Guido and everything he represents, but it's pretty awesome.