mobile

There's a lot of nifty tools that will automatically root my phone with pre-packaged system images (CF-Auto-Root et al). However, I'd prefer not to load my phone with firmwares from internet strangers. Also, I try to avoid apps whose code I can't see (e.g. SuperSu).

What I'd like to do is take the system preloaded on my Galaxy Note 4 by Samsung (or the recovery image) and modify it manually so that I have root access. As I understand it, this should be a fairly reproducible process. (Chainfire wrote somewhere that he has a script that automatically generates rooted images from vendor images as new versions are released.)

Please, help me do it manually. Assume I have some general Linux knowledge (your typical Ubuntu user), but no Android development skills.