Huh? I currently work with some of the technologies you mention, but fail to see the connection to systems theory. Can you elaborate why e.g. jq or Erlang are relevant here?
- There is general systems theory [0] and within that systems engineering[1] where you will find software systems [2]
- OP is most likely talking about how to use of general theory of systems in different domains and not specifically software systems.
- If one considers JQ, SED and "One input stream, one output stream" and then compares that to a model of a system using a CLD (Causal Loop Diagram). A CLD is effectively "An input, followed by an output"
- Another word that could be used for "input stream" would be 'flow' from system dynamics [3]
- One could apply general systems theory (the abstract concept) to just about anything
[0] https://en.wikipedia.org/wiki/Systems_theory
[1] https://en.wikipedia.org/wiki/Systems_engineering
There are a _lot_ of systems out there that tie together various components with tools that behave a lot like jq (or literally are jq...)
There is nothing unique about jq in this regard, and there is nothing particularly “systems thinking” about any of them. You can and people have used them for decades without doing any special “systems thinking”.
Also a good example of loose coupling that allows for good thinking of systems.
In school we watched the 1990 movie [MindWalk](http://www.imdb.com/title/tt0100151/). You can watch it on YouTube https://youtu.be/Uec1CX-6A38
Does there have to be?
It's simply an example of a good systems pattern/approach.