The GNU Project hosts this essay, "The UNIX Shell As a Fourth Generation Language":

https://www.gnu.org/software/nosql/4gl.txt

The concept of language "generations" is mostly lost now, much like how we stopped inventing names for how densely we pack transistors onto silicon once we'd gotten to VLSI (Very Large Scale Integration); the point of the essay is that the shell complete with a userspace is a programming language in itself, and one which is much more programmable and extensible than, say, getting all of your data into a database and using SQL to manipulate it. It's a programmable environment, as opposed to a data silo, where the only tools you have are the ones the silo's implementer deigned to provide.