Hacker News Reader

you could start with the list of what's included in busybox:

https://busybox.net/downloads/BusyBox.html

the goal of busybox is to provided a stripped down posix userspace for use in embedded devices -- basically, provide enough posix utils to be able to do some useful shell scripting.

Start with file management utilities such as ls, cp, mv and rm.

Here’s a standard list of Unix commands: https://en.wikipedia.org/wiki/List_of_Unix_commands

It is probably more comprehensive than what you were after though...