After a number of years away from a GitHub type work environment I started to use RStudio for some data analysis and l am loving it. Recently I decided to start using GitHub again to store/share my code with folks that I'm working on things with. I saw some posts about SourceTree and decided to give it a go, having historically just used the Terminal. First couple days were soooo sweet, then one day I couldn't commit anything 'Permissions Error', What!
Turns out Apple doesn’t seem to remember SSH keys between reboots, OMG!
Fix here; specifically I used what is noted as Method 1: Add all known keys to the SSH agent.
On my way there I got really familiar with various GitHub references;
Reasonably good reminder of Vi commands https://www.oreilly.com/library/view/learning-unix-for/0596009151/ch04s05.html
I thought it might prove useful to capture here to save others from hours of searching and the brilliant pain of such a stupid issue taking so much time.