It has been a while since I did anything approaching proper coding and since I use it as a lifeline when things are getting bad, I thought it was time to make something again. The most* fun part of programming is discovering a problem in the development environment and disappearing into a rabbit-hole for days to eventually bring you to the point where you can actually start.
This time, it was vi not working because rvm had triggered a Homebrew update which hadn't worked properly because of an OSX upgrade and ... argh. Ultimately it was Xcode, then the Xcode command line tools being missing.
This is going to come up again, so here's a note for future me.
For boring reasons I do not (and cannot) run the latest version of OSX or the latest version of Xcode. Consequently, running
brew update && brew upgradegave me:
Error: Xcode alone is not sufficient on High Sierra. Install the Command Line Tools: xcode-select --installThat command is not going to work on older versions of OSX. It triggers another process which (I think) hunts for the very latest version of Xcode in the App Store and its tools. I don't have the latest Xcode so it fails to find anything useful.
After quite a bit of hunting I found I can download the exact version of the tools I need from the Apple Developer site.
Once this is downloaded and installed, everything works ok (although I did have some luck also fixing up Homebrew with