What programs in the Linux/GNU environment are basic - how can they be classified?

Question

linux

What commands do you need to be able to use to call yourself a confident Linux/GNU user?
I assume that these are commands of the following rows:
1. cd, cp, mv, rm, ...
2. echo, cat, grep, bash, ...
3. ...
What will be the third row? Let's say that I'm currently experiencing curiosity and interest in such commands of the following series:
1. ifup, ifdown, ifconfig, if*, iptables ...
2. apt-get, ...
3. grep, tail, ... I
use the series, those that I described came out, I want to create visualized communication graphs
I want to use something like this:
https://github.com/anvaka/VivaGraphJS
Nobody did this kind of research before me?

Answer 1

www.gnu.org/software
First of all - www.gnu.org/software/coreutils :)