@ndam The SSH shell is an interactive Elixir shell (IEX). All commands are performed in Elixir.
For instance, to perform
echo hello in IEX, you would type
System.cmd("echo", ["hello"]). There is also a utility called Toolshed that has some nice helpers.
An important thing to know about SSH is that it is there for the convenience of FBOS core contributors (FarmBot employees and outside contributors that are building features intended to be merged back into the codebase). It is not our goal to provide a complete Linux shell environment for end-users. Particularly, this means that there are no plans to add package managers or alternative init systems.
With regards to your question about WiFi power management- I am unsure. Is that a kernel config? We keep our defconfig files over here if you would like to take a look. Does that help? Please let me know. Knowing more about the problem you are trying to solve would also be helpful.